Herschel Space Observatory Cast

Planck Casts New Light on Stellar Formation

2010-04-27T04:30:00.000-07:00

A series of recent experiments has revealed that, more often than not, the halos of dark matter surrounding massive galaxy clusters are flattened and shaped like a cigar. Until now, astrophysicists believed that the mysterious stuff, which is believed to be five times more abundant than regular matter around the Universe, would clump up in rounded spheres. However, observations appear to paint a different picture, and experts are currently working on models that would help explain that.

The discovery could finally lead to studies that would result in the direct detection of the peculiar type of matter, whose existence can only be inferred from the gravitational pull it exerts on normal matter around it. “There are clear theoretical predictions that we expect dark mater halos to be flattened like this. It's a very beautiful, very clean and direct measurement of that,” explains expert Graham P. Smith, who is based at the University of Birmingham, in the United Kingdom. He is also a coauthor of the new study, which will appear in an upcoming issue of the esteemed scientific publication Monthly Notices of the Royal Astronomical Society.

In the new studies, the investigators looked at about 20 galaxy clusters, which are massive collections of galaxies, held together by strong gravitational interactions. In order to see the effect dark matter has on the largest organized structures in the Universe, the researchers used gravitational lensing. This observations technique analyzes how much light is bent when mass wraps time-space in order to determine the mass of celestial objects beyond. The Mauna Kea, Hawaii-based Subaru Telescope was used for the study, and the team took advantage of the Prime Focus Camera above all other instruments.

“What we're probing with these gravitational lensing observations is the dark matter distribution, because the dark matter dominates the mass on these large scales,” Smith says. The research team in charge of the study was led by National Astronomical Observatory of Japan expert Masamune Oguri and University of Tokyo scientist Masahiro Takada. The cigar-like shapes of these dark matter halos have been predicted in computer models of the cold dark matter theory, but thus far they have not been evidenced in practice in such a large number of galaxy clusters, Space reports.

“Precise measurements of the Cosmic Microwave Background are crucial to cosmology, and to understanding how our Universe formed and evolved. Attaining the highest-sensitivity (a few parts per million), highest-angular resolution (5 arcminutes) maps of the CMB – the goal of the Planck mission – requires the removal of the 'foreground' emission arising from the Milky Way. The information gleaned during this process is providing, as a by-product, a unique view of the processes that led to the formation of the stars in the galaxies that populate our Universe,” ESA officials write in a press release.

Planck maps the sky in nine frequencies using two state-of-the-art instruments, designed to produce high-sensitivity, multi-frequency measurements of the diffuse sky radiation: the High Frequency Instrument (HFI) includes the frequency bands 100 – 857 GHz, and the Low Frequency Instrument (LFI) includes the frequency bands 30-70 GHz. The first Planck all-sky survey began in August 2009 and is 98% complete (as of mid-March 2010).

Baby stars in the Rosette cloud

2010-04-12T08:38:00.000-07:00

Infrared image of the Rosette molecular cloud. Herschel collects the infrared light given out by dust and this image is a three-colour composite made of wavelengths at 70 microns (blue), 160 microns (green) and 250 microns (red). It was made with observations from Herschel’s Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE). The bright smudges are dusty cocoons containing massive protostars. The small spots near the centre of the image are lower mass protostars.

Credits: ESA/PACS & SPIRE Consortium/HOBYS Key Programme Consortia

Herschel’s latest image reveals the formation of previously unseen large stars, each one up to ten times the mass of our Sun. These are the stars that will influence where and how the next generation of stars are formed. The image is a new release of ‘OSHI’, ESA’s Online Showcase of Herschel Images.

The Rosette Nebula resides some 5,000 light years from Earth and is associated with a larger cloud that contains enough dust and gas to make the equivalent of 10,000 Sun-like stars. The Herschel image shows half of the nebula and most of the Rosette cloud. The massive stars powering the nebula lie to the right of the image but are invisible at these wavelengths. Each colour represents a different temperature of dust, from –263ºC (only 10ºC above absolute zero) in the red emission to –233ºC in the blue.

The bright smudges are dusty cocoons hiding massive protostars. These will eventually become stars containing around ten times the mass of the Sun. The small spots near the centre and in the redder regions of the image are lower mass protostars, similar in mass to the Sun.

ESA’s Herschel space observatory collects the infrared light given out by dust. This image is a combination of three infrared wavelengths, colour-coded blue, green and red in the image, though in reality the wavelengths are invisible to our eyes. It was created using observations from Herschel’s Photoconductor Array Camera and Spectrometer (PACS) and the Spectral and Photometric Imaging Receiver (SPIRE).

Herschel is showing astronomers such young, massive protostars for the first time, as part of the ‘Herschel imaging survey of OB Young Stellar objects’. Known as HOBYS, the survey targets young OB class stars, which will become the hottest and brightest stars.

“High-mass star-forming regions are rare and further away than low-mass ones,” says Frédérique Motte, Laboratoire AIM Paris-Saclay, France. So astronomers have had to wait for a space telescope like Herschel to reveal them.

It is important to understand the formation of high-mass stars in our Galaxy because they feed so much light and other forms of energy into their parent cloud they can often trigger the formation of the next generation of stars.

When astronomers look at distant galaxies, the star-forming regions they see are the bright, massive ones. Thus, if they want to compare our Galaxy to distant ones they must first understand high-mass star-formation here.

“Herschel will look at many other high-mass star-forming regions, some of them building stars up to a hundred times the mass of the Sun,” says Dr Motte, who plans to present the first scientific results from HOBYS at ESA’s annual ESLAB symposium to be held in the Netherlands, 4–7 May.

Source: ESA

Planck sees tapestry of cold dust

2010-03-17T13:05:00.000-07:00

The image spans about 50° of the sky. It is a three-colour combination constructed from Planck’s two highest frequency channels (557 and 857 GHz, corresponding to wavelengths of 540 and 350 micrometres), and an image at the shorter wavelength of 100 micrometres made by the IRAS satellite. This combination visualises dust temperature very effectively: red corresponds to temperatures as cold as 10° above absolute zero, and white to those of a few tens of degrees. Overall, the image shows local dust structures within 500 light-years of the Sun.

Credits: ESA and the HFI Consortium, IRAS

Giant filaments of cold dust stretching through our Galaxy are revealed in a new image from ESA’s Planck satellite. Analysing these structures could help to determine the forces that shape our Galaxy and trigger star formation.

Planck is principally designed to study the biggest mysteries of cosmology. How did the Universe form? How did the galaxies form? This new image extends the range of its investigations into the cold dust structures of our own Galaxy.


	Planck scanning the sky

The image shows the filamentary structure of dust in the solar neighbourhood – within about 500 light-years of the Sun. The local filaments are connected to the Milky Way, which is the pink horizontal feature near the bottom of the image. Here, the emission is coming from much further away, across the disc of our Galaxy.

The image has been colour coded to discern different temperatures of dust. White-pink tones show dust of a few tens of degrees above absolute zero, whereas the deeper colours are dust at around –261°C, only about 12 degrees above absolute zero. The warmer dust is concentrated into the plane of the Galaxy whereas the dust suspended above and below is cooler.


Planck's newly imaged region shown in box

“What makes these structures have these particular shapes is not well understood,” says Jan Tauber, ESA Project Scientist for Planck. The denser parts are called molecular clouds while the more diffuse parts are ‘cirrus’. They consist of both dust and gas, although the gas does not show up directly in this image.

There are many forces at work in the Galaxy to help shape the molecular clouds and cirrus into these filamentary patterns. For example, on large scales the Galaxy rotates, creating spiral patterns of stars, dust, and gas. Gravity exerts an important influence, pulling on the dust and gas. Radiation and particle jets from stars push the dust and gas around, and magnetic fields also play a role, although to what extent is presently unclear.

Bright spots in the image are dense clumps of matter where star formation may take place. As the clumps shrink, they become denser and better at shielding their interiors from light and other radiation. This allows them to cool more easily and collapse faster.

Filamentary structures on large and small scales in the Milky Way

ESA’s Herschel space telescope can be used to study such regions in detail, but only Planck can find them all over the sky. Launched together in May 2009, Planck and Herschel are both studying the coolest components of the Universe. Planck looks at large structures, while Herschel can make detailed observations of smaller structures, such as nearby star-forming regions.

One puzzle to be solved is why there is similar filamentary structure on both the large and the small scale. “That’s a big question,” says Tauber.

The new image is a combination of data taken with Planck’s High Frequency Instrument (HFI), at wavelengths of 540 micrometres and 350 micrometres, and a 100-micrometre image taken in 1983 with the IRAS satellite.

The HFI data were recorded as part of Planck’s first all-sky survey at microwave wavelengths. As the spacecraft rotates, its instruments sweep across the sky. During every rotation, they cross the Milky Way twice. Thus, in the course of Planck’s mission to precisely map the afterglow of the big bang, it is also producing exquisite maps of the Galaxy.

Herschel Science Archive (HSA) and HIPE publicly [9 March 2010] available

2010-03-16T04:29:00.001-07:00

We are pleased to announce that as of today the Herschel Science Archive (HSA) has been opened to the world. At the same time the Herschel Integrated Processing Environment (HIPE) software has been made available for public download. For more information use the 'HIPE Download' and 'HSA Access' buttons on the left. [9 March 2010]

HIFI spectral scan of Orion [4 March 2010]

2010-03-16T04:28:00.000-07:00

The very successful commissioning and performance verification activities conducted with HIFI have produced a spectacular spectral scan of the Orion nebula. On the left above a spectrum displaying a plethora of lines from a number of molecules obtained in just a couple of hours, displaying the spectral richness so characteristic of Orion. On the right zooming in on smaller regions of the spectrum showing the unprecedented detail uniquely provided by HIFI. For additional information see the SRON and SciTech webpostings.

Herschel-HIFI unveils precursors of life-enabling molecules in Orion Nebula

2010-03-12T17:08:00.001-08:00

An artist's view of the Herschel satellite with the at present largest telescope mirror in space, which carries the HIFI instrument.

The HIFI spectrum of the Orion Nebula, superimposed on a Spitzer image of Orion. A characteristic feature is the spectral richness: among the organic molecules identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulphur oxide, sulphur dioxide and their isotope analogues. It is expected that new molecules will also be identified. This spectrum is the first glimpse at the spectral richness of regions of star and planet formation. It harbours the promise of a deep understanding of the chemistry of space once the complete spectral surveys are available.

Credit: ESA, HEXOS and the HIFI consortium

Press Release of the University of Cologne, Max Planck Institut für Radioastronomie, Bonn, and Max Planck Institut für Sonnensystemforschung, Lindau:

ESA’s Herschel Space Observatory has revealed the chemical fingerprints of potential life-enabling organic molecules in the Orion Nebula, a nearby stellar nursery in our Milky Way galaxy. This detailed spectrum, obtained with the Heterodyne Instrument for the Far Infrared (HIFI) - one of Herschel's three innovative instruments - demonstrates the gold mine of information that Herschel-HIFI will provide on how organic molecules form in space. Several German Institutes contributed essential parts to the HIFI instrument: the Universität zu Köln and two Max Planck Institutes: Radioastronomie (Bonn) and Sonnensystemforschung (Lindau).

Striking features in the HIFI spectrum include a rich, dense pattern of “spikes”, each representing the emission of light from a specific molecule in the Orion Nebula. This nebula is known to be one of the most prolific chemical factories in space, although the full extent of its chemistry and the pathways for molecule formation are not well understood. By sifting through the pattern of spikes in this spectrum, astronomers have identified a few common molecules that appear everywhere in the spectrum. The identification of the many other emission lines is currently ongoing.

By clearly identifying the lines associated with the more common molecules, astronomers can then begin to tease out the signature of particularly interesting molecules that are the direct precursors to life-enabling molecules. A characteristic feature of the Orion spectrum is the spectral richness: among the molecules that can be identified in this spectrum are water, carbon monoxide, formaldehyde, methanol, dimethyl ether, hydrogen cyanide, sulphur oxide, sulphur dioxide and their isotope analogues. It is expected that new organic molecules will also be identified.

“This HIFI spectrum, and the many more to come, will provide a virtual treasure trove of information regarding the overall chemical inventory and on how organics form in a region of active star formation. It harbours the promise of a deep understanding of the chemistry of space once we have the full spectral surveys available,” said Edwin Bergin of the University of Michigan principal investigator of the HEXOS Key Programme on Herschel.

Unprecedented high resolution

HIFI was designed to provide extremely high-resolution spectra and to open new wavelength ranges for investigation, which are inaccessible to ground-based telescopes. “It is astonishing to see how well HIFI works," said Frank Helmich, HIFI principal investigator of SRON Netherlands Institute for Space Research. "We obtained this spectrum in a few hours and it already beats any other spectrum, at any other wavelength, ever taken of Orion. Organics are everywhere in this spectrum, even at the lowest levels, which hints at the fidelity of HIFI. The development of HIFI took eight years but it was really worth waiting for.”

Identification of the many spectral features visible in the Orion spectrum with transitions of particular molecular species requires sophisticated tools such as the Colgone Database of Molecular Spectroscopy (CDMS), which collect the laboratory data of several hundred moelcular species and precise line predictions. “The high spectral resolution of HIFI shows the breath-taking rechness of molecular species, which are present, despite of the hostile environment, in the stellar nurseries and sites for planet formation”, says Jürgen Stutzki, HIFI-co-principle investigator at the Universität zu Köln.

ESA project Herschel:

Herschel is one of ESAs cornerstone missions, a space observatory with science instruments provided by European-led Principal Investigator consortia, with important contributions from NASA on the US side. One of the three instruments on board Herschel is HIFI, the Heterodyne Instrument for the Far-Infrared, .an ultra-sensitive, high resolution spectrometer designed and built by a nationally-funded consortium led by SRON Netherlands Institute for Space Research. The consortium includes partners from 25 institutes and 13 different nations. German institutes have provided key components for HIFI: the local oscillator, built at the MPI für Radioastronomie, Bonn, superconducting detectors with sensitivity close to the fundamental quantum limit, built at the Universität zu Köln. HIFI carries the classical radio frequency technique of heterodyne-mixing into a for orders of magnitude higher fequency regime, namely the Far-Infrared spectral range. A further essential component, the Acousto Optical Spectrometer (AOS), was developed in collaboration between the Universität zu Köln and the Max Planck Institut für Sonnensystemforschung, Lindau.

Log: (09-29-2009 - 11-25-2009)

2009-12-06T11:03:00.000-08:00

25 November 2009 (L+195, DOY 329)

The findings of the HIFI investigation team and the proposed plan for bringing HIFI back in operation were presented to the ESA Director of Science and Robotic Exploration and others in a briefing meeting held in ESTEC on 25 November 2009. The plan presented was endorsed, and is now the adopted way forward.

[G. Pilbratt, Herschel Project Scientist, posted 27 November 2009]

19 November 2009 (L+189, DOY 323)

The plan for bringing HIFI back in operation is now on the table, and subject to formal approval in the coming week. The plan consists of performing a number of software updates in the coming weeks, followed by a full instrument switch-on in January 2010, after which HIFI operations will resume. See information provided on the SRON website.

[G. Pilbratt, Herschel Project Scientist, posted 20 November 2009]

26 October 2009 (L+165, DOY 299)

The HIFI failure investigation team set-up at ESA in support of the Principal Investigator effort in SRON is finalising its work and a draft report is currently under review within the team. The content of this report will be presented to the ESA Director General and the Director of Science and Robotic Exploration this week. Due to the capability to perform extended tests on fully representative hardware and software on the ground, and to the excellent cooperation between the PI team and ESA specialists, the investigation has arrived at a complete and consistent failure scenario which can explain the observable evidence. Some further consolidating investigations on this scenario are still on-going but the picture that has emerged is the following:

A Single Event Upset (SEU) in the Random Access Memory (RAM) of the Local Oscillator Control Unit (LCU) microcontroller would be at the origin of a chain reaction that eventually results in an unplanned emergency switch off of sensitive instrument components. Designed to protect the local oscillators against damage from undervoltage on the spacecraft 28 V bus, this switch was thrown while the 28 V bus was alive. The resulting load transient in the internal power system of the LCU associated with this mode change created a stress in the power converters, leading to a permanent failure of one of the diodes.

Before the restart of the instrument on the redundant signal chain can be performed, changes in the operation and protection logic of the instrument must be implemented and validated in on-board software to prevent re-occurrence of such a sequence of events.

Although the detailed investigations have uncovered some marginalities in the stress applied to certain diodes in the internal power system of the LCU, laboratory tests have shown these diodes to be quite resilient against the short overvoltage spikes they are subjected to during nominal instrument operations. The investigation team is confident that HIFI can perform nominally for the remainder of the mission if the required corrective actions are implemented.

[J. Riedinger, Herschel Mission Manager and co-chair of the ESA investigation team]

5 October 2009 (L+144, DOY 278)

Progress towards re-enabling HIFI

Today, SRON have added an entry to their top level web page (www.sron.nl), in which they report about the progress that is being made towards re-enabling HIFI operations. Despite the progress which is undoubtedly made by the joint HIFI/ESA investigation team, the HIFI Project Manager cautions that switching the instrument back on may still be a few weeks in the future: We must ensure that we have taken all conceivable measures to minimise the risk of such a chain of events from happening again. One of these measures may require changes in on-board software, the validation of which would have to be performed with the utmost care.

[J. Riedinger, Herschel Mission Manager]

29 September 2009 (L+138, DOY 272)

First science data distributed to the users community

Yesterday 28 September Herschel reached another important milestone: the first set of observations corresponding to the so-called 'Science Demonstration Phase" were made available to their owners. This delivery took place several weeks ahead of the originally planned schedule and marks the start of the transition from the Performance Verification Phase to the Routine Phase of operations.

The observations (six so far only) were conducted on 12 September 2009 and successfully processed with the latest version of the pipeline as implemented in a dedicated version of HIPE that was also distributed to the observers. They are SPIRE scan maps of a variety of astronomical sources including a galactic HII region, a proto-planetary nebula, a supernova remnant, and a couple of galaxy clusters. This is the first of the observing modes released to the users community following its early validation during the Performance Verification Phase.

If there are no major contingencies, we expect to be running the Science Demonstration Phase at full speed during the second half of October and the whole month of November, as initially planned, first with PACS and SPIRE AORs, and then with HIFI as well, once the instrument resumes operations and completes its own performance and verification phase, delayed because of the problems already reported in this (B)log.

[P. Garcia-Lario, HSC ESAC, posted 30 September 2009]

First look at Herschel Spectroscopy

2009-12-06T11:00:00.001-08:00

ESA put out a major release today showing the first results from the spectrographs on Herschel. The release includes data on the Orion star formation region, on nearby and distant galaxies, on a massive star about to become a supernova and on a comet in our own solar system. The latter set of data was taken with HIFI before the technical fault that has left it shut down, awaiting a restart early next year.

These spectroscopic observations show the huge potential of Herschel to show us the physical and chemical processes going on inside dusty objects, be they star formation regions in our own galaxy, or in luminous interacting galaxies like Arp220 and Mrk231. My own research interests are more focussed on the distant luminous objects, and the data shown here from two archetypical ULIRGs (Ultraluminous Infrared Galaxies) are really spectacular. Never before have we seen the rich range of spectral lines that PACS and SPIRE have revealed in these objects.

PACS also holds out the hope of examining the velocity structure of some of these lines. This is particularly interesting in Mrk231 which hosts not only a massive burst of star formation but also a supermassive black hole powering a hugely luminous active galactic nucleus (AGN). The relationship between galaxy interactions and mergers in triggering both starbursts and AGNs is a hot topic, and Mrk231 makes an ideal testbed.

Finally, for sheer spectral richness and complexity, the PACS spectrum of the massive star VYCMa takes some beating. There’s a huge amount of physics and chemistry in this spectrum of a star deep into its old age and soon to become a supernova. Unfortunately this isn’t my area, so hopefully someone will add comments describing what the data means for this object.

For more information and coverage of these results see the ESA web release, BBC News Online, and the SPIRE website at Cardiff University.

Log: (06-19-2009 - 09-11-2009)

2009-09-16T12:58:00.000-07:00

11 September 2009 (L+120, DOY 254)

Update on the HIFI anomaly investigation

On Monday this week, the team established by ESA to investigate into the HIFI anomaly together with SRON met with instrument experts in Groningen for an extended question and answer session. Over the coming weeks the ESA team will help HIFI in trying to piece together what appears to be a complex puzzle of events which includes, but seems to be more complex than, failure of a DC/DC converter. By correctly understanding the failure scenario we hope to be able to minimise the risk when we switch HIFI back on, possibly using its redundant signal chain.

[J. Riedinger, Mission Manager and co-chair of the ESA investigation team]

4 September 2009 (L+113, DOY 247)

An update regarding the ongoing HIFI LCU malfunction investigation activities has today been posted on the ESA Corporate website.

The bottom line is that the investigation effort underway in SRON since the problem occurred is being augmented by an ESA team. The common objective is to determine the chain of events leading to the malfunction, and to decide when and under what conditions it can be considered safe to continue HIFI operations using the redundant set of warm electronics units.

[G. Pilbratt from ESTEC, posted 4 September 2009]

14 August 2009 (L+92, DOY 226)

Statement regarding HIFI LCU malfunction

On 3 August 2009 it was discovered by HIFI that on the day before the local oscillator control unit (LCU) had developed an anomaly leading to HIFI shutting down. Since then the HIFI consortium has been intensely investigating the nature of the problem; today the HIFI Principal Investigator Frank Helmich has provided the following statement:

"During normal check-out observations HIFI was shut down due to an unknown event in the analog voltage supply unit of the control electronics of the HIFI Local Oscillator. Engineers and scientists from the HIFI Instrument Control Centre and the hardware institutes are working to determine the cause and resume HIFI observations. An ongoing analysis suggests that there was either an upset in the power supply unit itself, or a voltage drop of the central unit supplying power to it. The power supply unit is needed for the instrument to obtain science observations. HIFI does have a duplicate, or redundant, set of electronics that will be used and which provides full functionality. The engineering and science team is working to understand the cause of the anomaly before switching to the duplicate set of electronics."

[G. Pilbratt from IAU GA in Rio de Janeiro, posted 14 August 2009]

10 July 2009 (L+57, DOY 191)

Herschel 'First Light' observations

You can now have a look at the 'first-light' observations released today, including SPIRE imaging of the nearby galaxies M66 and M74, HIFI spectroscopy of the star-forming region DR21, and PACS imaging spectroscopy of the planetary nebula NGC 6543.

The beauty and quality of these very first test observations is encouraging and demonstrates that a lot of new discoveries and exciting science is ahead of us! Follow Herschel progress also on the 'Latest News' page.

[P. Garcia-Lario, HSC ESAC, posted 10 July 2009]

7 July 2009 (L+54, DOY 188)

'First Light' web release this friday

A collection of 'First Light' images and spectra taken by the three instruments onboard Herschel during the days following the cryo-cover opening will be publicly made available this Friday 10 July. Watch out for the accompanying set of coordinated web releases by ESA and the different ICC consortia!

[P. Garcia-Lario, HSC ESAC, posted 7 July 2009]

3 July 2009 (L+50, DOY 184)

The coldest place in the outer space is no longer Herschel

Last night, the detectors of Planck's HFI (High Frequency Instrument) reached a temperature of 100 mK, making them the coldest thing in space, surpassing the record established by SPIRE detectors, which are operating at a warmer temperature of only 280 mK. After a successful orbit insertion maneouvre started at 13:15 CEST yesterday, Planck has now entered its final orbit around L2. Congratulations to our Planck colleagues!

[P. Garcia-Lario, HSC ESAC, posted 6 July 2009]

2 July 2009 (L+49, DOY 183)

50 days in space

Today is the 50th day of Herschel in space. As of yesterday, 80% of the planned commissioning phase activities have been executed. The initial check-out comprises a large number of tests, including switching-on of all instruments, basic functional tests, controlled cooling of the telescope, local oscillator stability measurements by HIFI, determination of the cooler recycling hold times by PACS and SPIRE, cryo-cover opening and initial determination of the focal plane geometry following 'sneak previews' of the infrared sky by all instruments, among many other checking activities. After a (so far) flawless period of almost 2 months of Commissioning Phase, with Herschel functioning nominally, we are now looking forward to starting the Performance Verification phase activities formally, something currently expected to occur on 16 July.

[P. Garcia-Lario, HSC ESAC, posted 6 July 2009]

29 June 2009 (L+46, DOY 180)

The Uplink validation chain

Before any observations can be uplinked to Herschel they must go through a series of rigorous tests. The HSC is the "meat in the sandwich" between ICC and MOC when carrying out uplink validation. The aim is to ensure that Herschel is protected from receiving any commands that could, potentially, be harmful and that nothing that has not been fully validated gets even as far as MOC, let alone to the spacecraft.

The Instrument Control Centres (ICCs) usually have to prepare their observation requests under great stress and time pressure, so it is essential to ensure that everything that has been delivered is correct and self-consistent and using the latest version of the uplink software, orbit file, etc. Under pressure, it is easy to make a mistake and deliver a wrong file in the middle of dozens of correct ones. Similarly, there is information that a particular ICC does not and cannot know when it is preparing its own observations, especially when a particular day is shared between two or more instruments: how much time is needed to slew from the end position of the first instrument's observations to the start position of the other's? Is the slew pattern acceptable to Flight Dynamics? Do all the observations from the different instruments fit in to the time available when combined?

If an inconsistency is found in validation, it must be understood and, almost invariably, the delivery is rejected and must be re-delivered. Only when the uplink information has been fully validated does it then go to the HSC Mission Planners who put together the final observing schedule and apply the last layer of checks, comparing between the schedule that is expected from the ICC input and the one that is actually obtained when that input is processed at the HSC. If a discrepancy is found, however trivial, it must be queried and if a change has had to be made to the sequence of observations, approval for the change must be sought from the ICC. Only when the "i"s are dotted, the "t"s crossed and everything is shipshape and Bristol fashion will the planning files be passed to the Project Scientist for his approval of the schedule and then on to MOC for transmission to the spacecraft.

The HSC Uplink Validation Team:
Delivery validators - Larry O'Rourke and Mark Kidger
Mission Planning - Charo Lorente and the Mission Planning Gang (Álvaro Llorente, Fernando Rodríguez and Mar Sierra)

[M. Kidger, HSC ESAC posted 6 July 2009]

25 June 2009 (L+42, DOY 176)

Can Herschel see Planck?

Some people may think that Herschel and Planck are quite close together in their orbits around the Second Lagrange Point of the Sun-Earth system and that a hypothetical observer on Herschel would be able to see Planck and vice-versa. How true is this?

At launch, of course, Herschel and Planck were very close together, but they separated quite quickly. At midnight on launch day the two were just 44 km apart and to a hypothetical stowaway on Herschel, Planck would have been about magnitude -3, but this distance between them increased quickly and, as a result, Planck would have faded rapidly from sight. By early on the morning of 17 May it would have been lost to the naked eye. On 29 May the separation between the two passed 50 000 km and on 7 June it passed 100 000 km. At the same time, the relative velocity between Herschel and Planck has increased considerably from the initial 1.3 m/s at 00UT on 15 May, to a maximum velocity of recession of 130 m/s on 18 June. In contrast, on 22 August, Planck will be approaching Herschel at no less than 119 m/s.

The distance and relative velocity between Herschel and Planck follow an approximately 3 month cycle. However, they are never separated by less than 0.5 Lunar Distances (LD) and the separation reaches a maximum value of 1.225 LD (471 000 km). Over the course of 2009, the closest approaches are on 5 September (207 000 km) and 4 December (159 000 km), with maximum separations on 26 July (471 000km) and 16 October (458 000km). Seen from Herschel, Planck is never brighter than V=14.9 and gets as faint as V=17.2

A Herschel or Planck ephemeris can be generated for any observing site on Earth or in space using JPL's Horizons system.

[M. Kidger, HSC ESAC, posted 6 July 2009]

Herschel's 'first-light' - venturing into uncharted waters

2009-07-13T05:40:00.001-07:00

The Herschel 'sneak preview' images of the nearby 'grand spiral' galaxy M51 at 70, 100, and 160 µm captured by the Herschel/PACS photometer and very quickly successfully processed on the ground demonstrated good overall performance in many crucial respects for Herschel as an observatory. In particular very promising optical performance was indicated by comparison with existing Spitzer/MIPS images. These Herschel/PACS images gave an exciting glimpse of things to come in a part of the far infrared spectrum where observing capabilities have been provided in the past with smaller aperture telescopes, demonstrating the power and good performance of Herschel's large telescope.

Providing a large telescope in space is a very important facet of Herschel, but just as important are pushing into the submillimetre part of the far infrared spectrum for the first time and providing instrumental capabilities never before realised in a space observatory. Building on the achievement of the 'sneak preview' Herschel has now gone further and ventured in several directions into previously virgin territory!

Herschel/SPIRE photometry of nearby galaxies

The SPIRE instrument on board Herschel has made its first test astronomical observations, with spectacular results. The SPIRE photometer performs broadband imaging at 250, 350, and 500 µm simultaneously, it is designed to observe emission from clouds of dust in regions where stars are forming in our own and other galaxies, nearby and distant. During OD#42 (24 June) SPIRE was able to observe the sky for the first time. Herschel was trained on two galaxies located in a convenient part of the sky just to get a first impression of what SPIRE could see. Scan-mapping with cross-scans of fields 20x20 arcmin around the target galaxies M66 and M74 were performed. The data were processed and images were made with 'naive' mapmaking algorithms. The results were better than anyone expected from first-look observations, made before any attempt to set up the instrument or to tune the image-making software. The target galaxies showed up prominently, providing by far the best images yet seen at these wavelengths, and many other, more distant, galaxies were also seen in the field of view.

The picture above shows SPIRE images of the two nearby galaxies, M66 and M74, at a wavelength of 250 µm. The images trace emission by dust in clouds where star formation is active, and the nucleus and spiral arms show up clearly. Dust is part of the interstellar material that fuels star formation, and these images effectively show the reservoirs of gas and dust that are ready to be turned into stars in the galaxies. Very significantly, the frames are also filled with many other galaxies which are much more distant and only show up as point sources, and there are also some extended structures, possibly due to clouds of dust in our own galaxy.

These images provide astronomers with an exciting foretaste of the exciting scientific studies planned with Herschel in general and SPIRE in particular: looking at star formation close up in our own galaxy and in nearby galaxies, and searching for star-forming galaxies in the very distant Universe. Because these galaxies are so far away, their light has taken a very long time to reach us, so by detecting them we are looking into the past and learning how and when galaxies like our own - the Milky Way - were formed.

To illustrate the advances made by Herschel, the pictures above compare the SPIRE image of M74 with the best previous image in a nearby part of the spectrum, made by NASA's Spitzer space observatory at a wavelength of 160 µm, the longest provided by Spitzer/MIPS. The differences in the two images are attributable to the much larger Herschel telescope and to SPIRE's highly sensitive detectors.

The picture above shows SPIRE images of M74 at all its three wavelengths, scaled to bring out the extended structure of the galaxy and to show more detail in the background sky. The image quality is of course best at 250 µm, the shortest wavelength. By combining the data from all three images, the properties of the emitting dust can be studied and the nature of the many distant galaxies that also appear in the pictures can be addressed.

Herschel/HIFI terahertz spectroscopy

While both the PACS and SPIRE instruments are imaging instruments designed to cover large areas of real estate on the sky, Herschel's third instrument HIFI provides complementary extremely high resolution spectral information on selected targets. HIFI is a unique instrument for a space observatory, offering heterodyne spectroscopy at frequencies never before available and with a wide spectral coverage which will enable detailed study of the dynamics and astrochemistry in a wide variety of astrophysical objects in our solar system, our galaxy, and beyond.

For its 'first-light' observation on OD#39 (22 June) HIFI was pointed at the giant molecular cloud DR21. Deeply hidden within the cloud newly formed massive stars are wreaking havoc on their stellar nursery.

In the composite image above HIFI spectra are overlaid on a Spitzer image at wavelengths much shorter than Herschel can observe. The Spitzer image shows the DR21 star forming region in false colours (IRAC 5.8 µm in blue and 8.0 µm in green, and MIPS 24 µm in red), the green reveals the emission from large molecules set aglow by the newly formed stars. The large bubbles and striated appearance of the cloud are caused by the complex dynamical interaction of the newly formed massive stars and the environment from which they formed. At bottom right there is a blow up of the active region where all these interactions are taking place, which is exactly what HIFI has been designed to study.

The observations were performed as part of the initial testing of different HIFI observing modes. The blue and red boxes show the areas that have been surveyed for ionized carbon (C⁺ at 1900 GHz), a key diagnostic of the molecular cloud material. These observations were performed as a fast double beam switch raster map. The broad line at the position of the newly formed star (in red) reveals the presence of a powerful wind ripping the cloud apart. In contrast, the off-star position (in blue) shows emission from quiescent material, which has not (yet) been disturbed by this star. The yellow stripe indicates the region studied in lines of water (H₂O (1₁₁-0₀₀) at 1113 GHz, right) and carbon monoxide (¹³CO (10-9) at 1101 GHz, left) by HIFI. The large width of the carbon monoxide profile and the complex and distorted water line again indicate that this material is part of a massive outflow from the newly formed star.

Herschel/PACS imaging spectroscopy

Both PACS and SPIRE can be operated as either photometers or imaging spectrometers. On OD#41 (23 June) the PACS integral field spectrometer was used for the first time for a test observation. The PACS spectrometer images a field on the sky in the light emitted by an individual spectral line, which can be used to diagnose physical properties and chemical composition.

The 'first-light' observation for the PACS spectrometer was performed of NGC6543 in the constellation of Draco, also known as the 'Cat's Eye' nebula, which was first discovered by William Herschel in 1786. The 'Cat's Eye' is a planetary nebula, consisting of a glowing shell of gas and plasma formed around an evolved star, and is a very well studied object, perfectly suited for observation with a new observatory. ESA's Infrared Space Observatory (ISO) already performed spectroscopic observations in the far-infrared on it and found bright line emission. However, at these long wavelengths with a 60 cm telescope ISO could not resolve any structure in, but with the help of Herschel's 3.5 m telescope the PACS spectrometer might.

PACS observed the nebula in two spectral lines, the fine structure line of doubly-ionised nitrogen (N²⁺) at 57 µm and the fine structure line of neutral oxygen (O) at 63 µm. For better orientation the PACS photometer was used to make a small map of NGC6543 in its 70 µm band, showing the structure of a dust ring with an opening on one side.

The picture above shows a Spitzer/IRAC near-infrared image of the entire nebula (left) for orientation, and individual spectra of the far-infrared nitrogen line, all taken simultaneously with the PACS spectrometer in the inner region of the nebula. The spectra are overlayed on the dust continuum as observed with the PACS photometer.

The second picture shows a comparison of the two observed lines. The images have been reconstructed from a mosaic of 9 overlapping 'snapshots' of the kind shown in the previous panel. The two lines clearly originate from different components within the object - where the ionised nitrogen emission is brightest, there is a 'hole' in the neutral oxygen. This is most clearly seen in the composite image, with the oxygen line shown in green and the nitrogen line shown in red.

Already, these very first data fulfill the expectations at this point and are of unprecedented sensitivity, accurately tracing the physical conditions in cold and warmer gas. Being a first test, while these spectra are excellent on a qualitative level, the super-position of the individual spectra on the continuum image still needs to be verified, and the line intensities are non-quantitative. This is work to come!

Herschel as an observatory

The very first test observations have generated spectacular data as shown in the 'sneak preview' and 'first light' releases! That this has been possible on very short timescales is a testament to the overall vision of how the Herschel mission and science operations were planned to work, and of all the ground testing and preparations, including very extensive operations simulations, that have been performed leading up to the in-flight operations.

What has been achieved so far - remember this is but the very beginning! - is very encouraging for the future, both with respect to the performance of the 'space segment' - the Herschel satellite - and the 'ground segment' which involves the ESA Herschel mission operations and science centres (MOC and HSC), in partnership with the instrument control centres (ICCs) provided by the PI consortia, and the NASA Herschel Science Center (NHSC).

Göran Pilbratt (Herschel Project Scientist) based on inputs provided by the Herschel Principal Investigators Matt Griffin (SPIRE), Frank Helmich (HIFI), and Albrecht Poglitsch (PACS)

Log: (6-7-2009)

2009-07-08T06:18:00.000-07:00

'First Light' web release this friday

[P. Garcia-Lario, HSC ESAC, posted 7 July 2009]

Log: (7-3-2009)

2009-07-06T13:10:00.002-07:00

The coldest place in the outer space is no longer Herschel

[P. Garcia-Lario, HSC ESAC, posted 6 July 2009]

Log: (7-2-2009)

2009-07-06T13:10:00.001-07:00

50 days in space

[P. Garcia-Lario, HSC ESAC, posted 6 July 2009]

Log: (6-29-2009)

2009-07-06T13:09:00.001-07:00

The Uplink validation chain

[M. Kidger, HSC ESAC posted 6 July 2009]

Log: (6-25-2009)

2009-07-06T13:04:00.000-07:00

Can Herschel see Planck?

A Herschel or Planck ephemeris can be generated for any observing site on Earth or in space using JPL's Horizons system.

[M. Kidger, HSC ESAC, posted 6 July 2009]

Log: (6-19-2009)

2009-07-06T13:02:00.001-07:00

Herschel opened its infrared eyes

On 14 June 2009 PACS obtained images of M51, the 'Whirlpool Galaxy' in its first test observation immediately following cryo-cover opening. The images, obtained at 70, 100 and 160 microns are shown below and demonstrate that the optical performance of Herschel and its large telescope is meeting their high expectations.

[P. Garcia-Lario, HSC ESAC, posted 6 July 2009]

Picture of the Day #3

2009-06-29T05:28:00.000-07:00

Carina Nebula

Zoom-able Image

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Caption in Image Archive

Herschel and Planck in the classroom

2009-06-29T05:17:00.000-07:00

To mark the launch of the Herschel and Planck space observatories, ESA has participated in the production of a wide-ranging series of educational materials related to these two cornerstones of its science programme.

These materials were originally disseminated to German teachers through a collaboration with the German “Wissenschaft in die Schulen!” (WiS! - Science into Schools!) project and the “Sterne und Weltraum” magazine. ESA is now making them available online through its education website.

The launch of Herschel and Planck on 14 May 2009 marked the beginning of a new era in observational astronomy. When they reach their operational orbits later in the year, Herschel will provide new insights into the births of stars and galaxies, while Planck will map the Cosmic Microwave Background – the relic radiation of the Big Bang – with unprecedented accuracy. The first observatory to cover the entire range from far-infrared to sub-millimetre wavelengths and bridge the two, Herschel will explore further in the far-infrared than any previous mission, studying otherwise invisible dusty and cold regions of the cosmos, both near and far.

WiS! recognised the importance of this scientific milestone by dedicating a special edition of “Sterne und Weltraum” to the pair of pioneering missions. This issue included numerous articles written by scientists involved in the missions, as well as didactical material written by educational experts in the field. The teaching materials, mainly aimed at secondary school students, covers various mission-related topics such as orbits, Lagrange points, the Big Bang and electromagnetic radiation.

The articles and corresponding exercises can be downloaded in English and in German from the ESA Education website. The original publication, which was made available to teachers during workshops in Germany, included a DVD that contained three educational videos. These can also be found on the ESA Education website.

“Wissenschaft in die Schulen!”

The “Wissenschaft in die Schulen!” project started in 2005 with support from the German Klaus Tschira Foundation, a non-profit organisation designed to support research and public understanding of science and mathematics. Through close collaboration with the magazine “Sterne und Weltraum”, it includes a wide range of interesting subjects derived from recent astronomical research and space travel for use in lessons.

Thanks to the publisher Spektrum der Wissenschaft, the project has developed teaching materials for lower and upper secondary classes, based on subjects covered in its monthly scientific magazines. These materials are made available to a wide audience through a magazine and a website. Teachers can now find 80 lessons online on the “Wissenschaft in die Schulen!” website.

Herschel and Planck educational materials

Herschel’s daring test: a glimpse of things to come

2009-06-19T04:59:00.001-07:00

Herschel's test view of M51

19 June 2009
Herschel opened its 'eyes' on 14 June and the Photoconductor Array Camera and Spectrometer obtained images of M51, ‘the whirlpool galaxy’ for a first test observation. Scientists obtained images in three colours which clearly demonstrate the superiority of Herschel, the largest infrared space telescope ever flown.

This image shows the famous ‘whirlpool galaxy’, first observed by Charles Messier in 1773, who provided the designation Messier 51 (M51). This spiral galaxy lies relatively nearby, about 35 million light-years away, in the constellation Canes Venatici. M51 was the first galaxy discovered to harbour a spiral structure.

The image is a composite of three observations taken at 70, 100 and 160 microns, taken by Herschel’s Photoconductor Array Camera and Spectrometer (PACS) on 14 and 15 June, immediately after the satellite’s cryocover was opened on 14 June.
Herschel, launched only a month ago, is still being commissioned and the first images from its instruments were planned to arrive only in a few weeks. But engineers and scientists were challenged to try to plan and execute daring test observations as part of a ‘sneak preview’ immediately after the cryocover was opened. The objective was to produce a very early image that gives a glimpse of things to come.

M51 seen by Spitzer (left) and Herschel (right)

To the left is the best image of M51, taken by NASA’s Spitzer Space Telescope, with the Multiband Imaging Photometer for Spitzer (MIPS), juxtaposed with the Herschel observation on 14 and 15 June at 160 microns. The obvious advantage of the larger size of the telescope is clearly reflected in the much higher resolution of the image: Herschel reveals structures that cannot be discerned in the Spitzer image.

M51 Herschel image at 160, 100 and 70 microns

Herschel’s glimpse of M51 at 70, 100, 160 microns.

These images clearly demonstrate that the shorter the wavelength, the sharper the image — this is a very important message about the quality of Herschel’s optics, since PACS observes at Herschel’s shortest wavelengths.

Produced from the very first test observation, these images lead scientists to conclude that the optical performance of Herschel and its large telescope is so far meeting their high expectations.

Herschel cryocover is open

2009-06-16T06:07:00.001-07:00

(ESA) - At 12:53 CEST yesterday, the cryocover of the Herschel satellite was opened after the spacecraft received a command to fire pyrotechnic bolts holding it down. This crucial step brings ESA’s newest space telescope one step closer to starting its scientific mission.

The cryocover is the Herschel telescope’s ‘lens cap’: it provides a high-vacuum tight closure of the cryostat on ground and during the early orbit phase, and preserves the cryogenic environment of the instrument focal plane units during activities on ground. With the cryocover on, the instruments and the telescope cannot ’see’.

Artist concept of the Herschel spacecraft

Herschel’s instruments

As Herschel is now in the vacuum of space and the first few weeks of out-gassing have passed, the cryocover could be opened safely. The command to open the cryocover was issued manually by spacecraft controllers at ESOC, ESA’s European Space Operations Centre, in Darmstadt, Germany. Telemetry received just afterwards from the spacecraft indicated that the cryocover had reached the open position.

Peeking through the launcher fairing

“The cryocover swung back and forth six or seven times, shaking the satellite somewhat, and there were changes in temperature at several points, as expected. All this is consistent with the cryocover opening successfully. The final positive confirmation will come from the measurements of the optical background via the Photoconductor Array Camera and Spectrometer instrument, which are underway this week,” said Göran Pilbratt, ESA Herschel Project Scientist, speaking at ESOC.

Herschel’s sophisticated cooling system

The satellite is undergoing a series of post-launch check-outs and confirmations that will be followed by a thorough performance validation of the sophisticated instrument suite. This process will continue until late autumn when routine science operations will start.

As of 14 June, Herschel was located approximately 1 425 000 km from Earth.

Log: (06-14-2009)

2009-06-15T06:47:00.001-07:00

14 June 2009 (L+31, DOY 165)

At 10:53:17 UTC this morning the Herschel cryocover was commanded to open by manual commanding from the MOC at ESOC.

The command was executed nominally, there is telemetry indicating that the cover reached the open position, the shaking of the spacecraft caused by the opening was seen on the gyros and the phase separator, and the temperatures at L0 and L1 slightly changed.

All of this is consistent with what you would expect from a successful cryocover opening!

[G. Pilbratt, from MOC ESOC, posted 14 June 2009]

Herschel telescope opens eyes

2009-06-14T09:10:00.000-07:00

You can Read the Herschel Log here.

By Jonathan Amos
Science reporter, BBC News, Le Bourget

Europe's new billion-euro Herschel space observatory, launched in May, has achieved a critical milestone.

The telescope has opened the hatch that has been protecting its sensitive instruments from contamination.

The procedure allowed light collected by Herschel's giant 3.5m mirror to flood its supercold instrument chamber, or cryostat, for the first time.

The observatory's quest is to study how stars and galaxies form, and how they evolve through cosmic time.

The command sent on Sunday to fire two pyrotechnic bolts holding down the hatch was arguably the key moment in the European Space Agency (Esa) mission since the 14 May launch from Earth.

"We need the lid open or we can't see the sky, so it's a really important event," said Professor Matt Griffin, the principal investigator on SPIRE, one of three instruments inside the cryostat.

There is a YouTube video that shows what would have happened - in slow motion.

News of the hatch opening came on the eve of the Paris air show, a big event in the space calendar when Esa and the space industry come together to celebrate their achievements.

A Herschel display is a prominent feature in the Esa pavilion which the public can visit from Friday 19 June, after the trade days here at Le Bourget that run from Monday to Thursday.

Herschel's instruments sit inside a tank kept at supercold temperatures

During final ground testing (L), the cryostat was sealed and evacuated

Only in the vacuum of space (R) can the cryostat be opened up safely

The lid release allows light from the mirror to reach the instruments

It was a critical procedure - failure would have killed the entire mission

Scientists stress it will be a while yet before they are ready to release a "first light" image from the telescope. Herschel is little more than half way through its check-out phase and it is still several weeks away from beginning full operations.

The astronomical community - and the public - will have to be patient as they wait for Esa's flagship space telescope (which is bigger than Hubble in mirror diameter) to show off its capability.

Herschel is sensitive to light at long wavelengths - in the far-infrared and sub-millimetre range.

This will allow it to see past the dust that scatters visible wavelengths, and to gaze at really cold places and objects in the Universe - from the birthing clouds of new stars to the icy comets that live far out in our Solar System.

Herschel was launched on an Ariane 5 rocket in May

The observatory is tuned to see the Universe in the far-infrared

Its 3.5m diameter mirror is the largest ever flown in space

Herschel can probe clouds of gas and dust to see stars being born

It will investigate how galaxies have evolved through time

The mission will end when all the superfluid helium boils off

For the observatory to see these phenomena requires that it, too, be very cold. Superfluid helium is used to take its instruments very close to "absolute zero" (-273C). This is done inside a huge evacuated tank.

For nearly two years, the instruments have been locked away in the top of this cryostat to maintain their frigid state and protect them from contamination. Only now - a month into the mission - was it considered safe to open the lid.

"Anything that's launched into space always has some water vapour and various other contaminants - volatile gases - absorbed in its materials; and in space the water and these volatiles slowly boil away into the vacuum of space," explained Professor Griffin, who is affiliated to Cardiff University, UK.

"It is conventional and necessary to wait for this to happen, to make sure these contaminants don't find their way inside the cryostat where they could condense in the instruments."

Herschel is heading for an observation position some 1.5 million km from Earth. It is more than 90% of the way there.

Indeed, its distance from home is now so great it took almost five seconds for the pyro command to reach Herschel. A slight temperature rise and a shaking detected on the spacecraft indicated to controllers that the lid opening was successful.

Source:- http://news.bbc.co.uk/2/hi/science/nature/8099105.stm

Planck Chills Out

2009-06-12T17:07:00.001-07:00

Artist's concept of Planck in space, with Earth in the background. Image credit: ESA› High-resolution JPEG (1.5MB)

June 12, 2009

A JPL-developed and -built cooler on the Planck spacecraft has chilled the mission's low-frequency instrument down to its operating temperature of a frosty 20 Kelvin (minus 424 degrees Fahrenheit). The so-called hydrogen sorption cooler was turned on June 4 and achieved the target temperature of 20 Kelvin eight days later. The cooler is part of a chain of coolers that works together to ultimately chill the high-frequency instrument down to 0.1 Kelvin -- an event scheduled to take place in a few weeks.

Planck is currently on its way to its final orbit at the second Lagrange point, which is located about 1.5 million kilometers (930,000 miles) from Earth, on the opposite side of our planet from the sun. Once there, it will look back to the dawn of time to study the birth of our universe.

Herschel mission timeline

2009-06-11T15:56:00.001-07:00

Herschel mission timeline

Commissioning: Days 1 – 60 (mid-May – mid-July 2009)

The first two months of Herschel’s life in space are being used to check out thoroughly all aspects of the spacecraft and the instruments to make sure everything has survived the launch and works properly in space. For most of this time Herschel will be moving steadily away from the Earth, on the way to its final orbit about the L2 point.

A key moment during Commissioning will be the opening of the cryostat lid. The instruments are contained in vacuum inside the cryostat, and for testing on the ground, the vacuum was maintained by an airtight lid on the top. Once in space, where there is a vacuum, the lid can be removed so that the light collected by the telescope can get in to the instruments. Removing the lid is a critical operation – if it is not removed successfully, Herschel will not be able to make any observations because the instruments will not be able to see the sky. This will be done around Day 35 (June 17). The reason it was not done straight after launch is that it takes a few weeks for the spacecraft to “out-gas” traces of water in its various materials (inevitable in anything manufactured on Earth). The lid is kept closed while this happens to make sure that none of the evaporating water can get into the cryostat and condense as ice inside the instruments.

The image on the left shows Herschel set-up for testing on the ground before launch. The lid is on, keeping the instruments under vacuum. The instruments can’t actually see the telescope – this will happen for the first time in space when the cover is removed. The image on the right shows Herschel in space after the lid is removed. The light collected by the telescope can now get to the instruments.

This movie shows a test of the lid release mechanism. Once released, it springs back and after a few oscillations it settles in a position that does not block the light collected by the telescope from entering the cryostat and being detected by the instruments. This is scheduled to happen about a month after launch. [Credit: European Space Agency]

Performance verification: Days 60 – 150 (mid-July to mid-October 2009)

After everything has been checked out, the three Herschel instruments will be put through their paces by making every possible kind of observation and setting up each observing mode to give the best results. The data processing software will also be tested and improved if necessary to make sure that the highest quality scientific results can be produced. All that will take another three months to complete. Then Herschel will be fully ready for science observations.

Science demonstration: Days 150 – 190 (mid-October – end November 2009)

To show the world what Herschel can do, and to generate some early scientific results, the next six weeks (Days 150-190) will be used to make scientific observations covering the whole range of Herschel’s capabilities – a little bit of everything that Herschel can do covering the solar system out to the most distant reaches of the Universe. The results will be analysed quickly and presented at a European Space Agency workshop in December.

Routine operations

Herschel will then settle down to at least three years of operation. Roughly half of that time has already been allocated to “Key Projects” – big observational programmes designed for in-depth investigation of some of the main questions that Herschel has been designed to answer. The second half of the mission will be available for smaller programmes and for following up some of the work done during the first part.

Extended lifetime?

When the helium in Herschel’s cryostat has all evaporated, the instruments will warm up and will no longer be able to operate – the mission will then be at an end. The minimum lifetime was designed to be 3.5 years, but the Herschel cryostat has been very well designed, and everything went very will with the launch, so it is possible that it might last even longer – an extra six months or a year would be very welcome to the queue of astronomers who want to use it.

Log: (06-11-2009) with Video

2009-06-11T15:51:00.001-07:00

11 June 2009 (L+28, DOY 162)

Opening of the cryocover

The opening of the cryocover is planned for Sunday 14 June. By then the telescope will have reached a temperature of about 120 K. The opening will enable the instruments inside the cryostat for the first time to see out to the real sky. You can get a very approximate idea of what is going to happen by watching the video below, available in YouTube, where the opening of the cryostat lid is shown in slow motion during one of the cryogenic qualification tests carried out by Austrian Aerospace and EADS Astrium at Friedrichshafen, Germany.

[P. Garcia-Lario from HSC ESAC, posted 11 June 2009]

Log: (06-10-2009)

2009-06-11T15:50:00.000-07:00

10 June 2009 (L+27, DOY 161)

Herschel! Herschel! Wherefore art thou Herschel?

Since launch Herschel has made various trajectory correction manoeuvres, the last of them on 10 June and, of course, now has an accurately measured orbit, rather than the predicted orbit that had to be used initially. So, where exactly is Herschel now and where will it be in the over the next few months?

Herschel is now effectively at the 2nd Lagrange Point of the Sun-Earth system and slowing rapidly as it reaches the apogee of its orbit. At 00UT on 12 June it will be receding at 168m/s. At 00UT on 22 June at 95m/s. And at 00UT on 2 July, at just 40m/s. Eventually, at 09:30UT approximately on 7 July, Herschel will reach apogee at 1.576 million kilometres from Earth and will then start to loop backwards until 5 September when it will be at perigee at a distance of 1.248 million kilometres.

As it comes in towards perigee, Herschel will drop below the ecliptic, crossing from Ophiuchus to Serpens, then back again briefly into Ophiuchus, before spending the second half of July and first half of August in Sagittarius. Finally, two and a half weeks before perigee, it will reach a minimum declination of -30 degrees in the southern constellation of Microscopium. By perigee, Herschel will have climbed through Piscis Australis to reach declination -21 degrees in Aquarius.

Herschel's magnitude will vary between V=19.5 at apogee and 19.0 at perigee. During the summer, as it passes through the dense star clouds close to the Galactic Centre, Herschel will be an extremely difficult object to observe from Earth.

Daily updates of Herschel's position are given in the Herschel Twitter Page (ESAHerschel)

A Herschel ephemeris can be generated for any observing site on Earth or in space using JPL's Horizons system and setting the target as "Herschel Space Observatory".

[M. Kidger from HSC ESAC, posted 11 June 2009]

Log: (06-09-2009)

2009-06-11T07:55:00.000-07:00

9 June 2009 (L+26, DOY 160)

Big helium venting nozzles closed

Yesterday 8 June the big helium venting nozzles were closed by telecommand from ESOC. Successful closure of the valves was immediately confirmed by an increase of the temperatures of the phase separator, the level 1 and the external vent line as well as the pressure in the external vent line. The cryostat behaviour is nominal.

This was the last planned activity on the helium system, from now on the cryostat will be in passive control.

[P. Garcia-Lario from HSC ESAC, posted 11 June 2009]

Log: (06-07-2009)

2009-06-10T07:47:00.001-07:00

7 June 2009 (L+24, DOY 158)

Space weather and SREM data during Days 1-21

Herschel has launched during what has been an unprecedentedly low minimum of solar activity in modern times, with more than 150 consecutive spotless days preceding launch. It is expected that Herschel operations will cover the rise to and peak of the next solar maximum, so monitoring space weather during the mission is important, as is the level of activity at maximum; predictions have stated that the later the rise to maximum starts, the lower the maximum is likely to be.

Herschel carries the SREM (Space Radiation Environment Monitor) as a passenger (left image below), to measure constantly the radiation environment to which Herschel is exposed. Herschel Science Centre scientists analyse this data daily and are looking for possible correlations with solar activity and with predictions of future activity.

On Day 18 a sunspot group with 13 spots formed, leading to a small (B1-class) flare at 08:07UT on June 1^st (OD-18), a second B1-class flare at 06:39UT on June 2^nd (OD-19). These were the first two flares registered during the mission. Later, three B-class flares were seen on June 3^rd (OD20-21).

SREM data (middle image below) shows that there has been no important activity registered in the SREM data since Herschel crossed the Van Allen Radiation Belts. The variations in count rate can all be attributed to noise.

The peak count rate during the Van Allen Belt crossing was about 3 orders of magnitude greater than the count rate at any other point during the transfer orbit. A closer look at the data on an expanded scale (right image below) shows no evidence of an increase in the SREM counts at the time of first two flares, which are marked with arrows.

[M. Kidger & M. Sánchez Portal from HSC ESAC, posted 9 June 2009]

Log: (06-02-2009)

2009-06-08T19:33:00.001-07:00

2 June 2009 (L+19, DOY 153)

First results from SPIRE spectrometer

The picture below shows the first SPIRE interferogram, observed on May 29 using the SPIRE Fourier Transform Spectrometer. This is a result of the first successful tests of the SPIRE spectrometer in space (although currently only viewing the cryostat lid and not yet the sky!).

[SPIRE team, posted 8 June 2009]

Log: (06-04-2009)

2009-06-08T05:54:00.000-07:00

4 June 2009 (L+21, DOY 155)

Attitude pointing responsibility transferred to the HSC

Once the spacecraft's Attitude Control & Measurement System (ACMS) has been declared 'commissioned' by the Mission Operations Centre (MOC), approval has been given to HSC to start using attitude request commands as of the start of the Daily Telecommunications Period (DTCP) of Operational Day 21, at 10:19z on 3 June. This means that from now until the end of the mission, the Mission Planning Team at the HSC is taking over attitude pointing responsibility.

[P. Garcia-Lario from HSC ESAC, posted 8 June 2009]

Log: (06-03-2009)

2009-06-06T18:53:00.000-07:00

3 June 2009 (L+20, DOY 154)

PACS grating and chopping initial functional tests completed

The commissioning of the chopper and grating (tuning of control parameters) has been completed today with an achieved performance equal or better than what was reached on ground.

The chopper behaviour was found to be identical to what was experienced during the ground tests, giving confidence that the chosen control parameters are robust against variations in the operational temperature of the chopper.

The very good stability of the grating was also confirmed with several sets of parameters.

As of today, the manual commanding of the PACS mechanics is finalised and the two mechanisms can be declared commissioned.

[B. Altieri & R. Vavrek, posted 5 June 2009]

Newly-launched missions extend ESA's radiation map of space

2009-06-03T06:18:00.000-07:00


Standard Radiation Environment Monitor (SREM)

As the Herschel and Planck observatories head towards their final orbits 1.5 million kilometres from Earth each spacecraft has a small but significant passenger aboard – a device no bigger than a shoebox, the latest in a family of monitors piggybacking on ESA missions to chart variations in radiation across different regions of space.

The instrument is known as the Standard Radiation Environment Monitor (SREM), and it has been designed to detect highly charged particles expelled from the Sun , surrounding Earth in radiation belts, or originating from interstellar space – known as 'cosmic rays'. The SREM's main purpose is to identify radiation hazards threatening its host spacecraft but also to yield a detailed picture of the space radiation environment.

Herschel and Planck are transporting their SREMs to the distant Second Lagrange Point (L2), a point in space behind Earth where combined solar and terrestrial gravity keeps the spacecraft orbiting the Sun at the same rate as the Earth. These monitors are joining identical SREMs already operational in a variety of other orbits:

in low-Earth orbit on the Proba-1 technology demonstrator
in medium-Earth orbit aboard the GIOVE-B test satellite for ESA's Galileo satellite navigation system
on the INTEGRAL gamma ray observatory whose highly eccentric orbit takes it a maximum 153,000 km from Earth
and aboard the Rosetta comet rendezvous mission, in deep space beyond Mars.

"For the first time we have been able to observe the same solar energetic particle events from different locations in the Solar System at the same time while using basically the same instrument," says Petteri Nieminen of ESA's Space Environment and Effects section. "That is quite unique."

Earth's magnetic field guards against interplanetary radiation, but its protection diminishes with distance. The lowest-altitude SREM aboard Proba-1 basically orbits within this 'magnetosphere', although its orbital path passes through a zone of heightened particle radiation known as the South Atlantic Anomaly.

Higher-orbiting SREMs pass out of the magnetosphere altogether, crossing through the bands of trapped radiation particles known as the Van Allen Belts, while the SREMs aboard Rosetta and now Herschel and Planck sample radiation away from Earth orbit in interplanetary space.

The devices can be thought of as the satellite equivalents of the radiation dosimeters worn by astronauts on-orbit. High levels of particle radiation can disrupt spacecraft electronics as well as degrade crucial onboard materials such as sensor lenses or solar cells. But its effects on unshielded human biology would be even worse.

"Radiation is going to be a crucial issue when it comes to planning the future human exploration of the lunar surface and Mars," explains Mr Nieminen. "Exposure to the highest energy protons and electrons detected by SREM could cause serious radiation sickness in unprotected astronauts."

The SREM design incorporates diodes that generate a measurable electric charge when they come into contact with energetic charged particles. Placed behind conical entrances, these diodes are sensitive to the direction as well as the charge and energy of incoming particles.

A batch of ten SREM units were constructed in 2000 by Swiss firm Oerlikon Space (then known as Contraves) working with Switzerland's Paul Scherrer Institute under ESA contract.

The design was developed from an earlier Radiation Environment Monitor (REM) flown on the UK's STRV 1B satellite and the Mir Space Station during the 1990s. The first SREM was flown on the STRV-1c satellite but its operation was cut short by spacecraft failure. With six further units now in space three more SREMs remain available for future flight opportunities.

SREM results to date are feeding back into future spacecraft designs. GIOVE-B's orbit for example takes it through the highly radioactive outer Van Allen Belt, and its findings have helped assess the shielding required for the operational Galileo satelllites set to follow it.

"The previous models we have been working with were based on old NASA data from the 1960-70s," says Mr Nieminen . "However with a European instrument we have been able to actually quantify the radiation and we do see some divergence between the old models and what we observed for ourselves."

The latest SREMs will probe radiation conditions prevailing in L2, likely to be valuable data for the many next decade missions headed for this region, including ESA's GAIA and the ESA-NASA James Webb Space Telescope.

Future missions will probably be carrying their own radiation detectors: ESA's Space Environment and Effects section is planning the development of next-generation units which will be much more compact than the 2.5 kg SREM while bettering their performance.

The current SREMs have exhibited very high sensitivity indeed, Mr Nieminen recounts: "On 27 December 2004, the unit aboard INTEGRAL even managed to detect an X-ray flare from a neutron star at the same time as its host satellite, something it was never designed to do."

Picture of the Day #2

2009-06-02T11:24:00.001-07:00

The Heart of the Trifid Nebula

The Trifid Nebula, cataloged by astronomers as Messier 20 or NGC 6514, is a well-known region of star formation lying within our own Milky Way Galaxy. It is called the Trifid because the nebula is overlain by three bands of obscuring interstellar dust, giving it a trisected appearance as seen in small telescopes. The Trifid lies about 9,000 light-years (2,700 parsecs) from Earth, in the direction of the constellation Sagittarius.

Credit: NASA, ESA, and The Hubble Heritage Team (AURA/STScI)

Log: (05-27-2009)

2009-05-27T14:48:00.000-07:00

27 May 2009 (L+13, DOY 147)

Following the successful switch on of HIFI and PACS during OD 11, all 56 PACS observations and 9 HIFI observations containing engineering data were processed successfully by the Herschel Data Processing pipeline to the expected level. Together with 6 SPIRE observations also executed during OD 11, and the available auxiliary files, they were ingested into the Herschel Science Archive, and are now available to the Herschel calibration scientists. Using for the first time in operations, the Herschel Data Processing software of the three instruments and the Herschel Science Archive system achieved a flawless end-to-end processing and archiving. Herschel has its archive populated before first light!

[S. Ott from ESAC, posted 27 May 2009]

Log: (05-26-2009)

2009-05-26T21:42:00.000-07:00

26 May 2009 (L+12, DOY 146)

On 24 May close to 17:00 UT the third and final Herschel science instrument, HIFI, was successfully switched on. In the following 30 hours it has undergone a series of tests that show the functionality of its focal plane units -- the 4 spectrometers, its electronics units and the main moving component its chopper. All items have been shown to be working in similar fashion to on-ground testing and all functional tests have been declared successful.

As HIFI is a heterodyne unit, it also requires the use of a local oscillator unit. HIFI has a sophisticated and complex local oscillator system that allows its spectrometers to obtain high-resolution spectra across a very wide range of frequencies. The local oscillator (LO) unit, with its 14 separate signal-carrying chains,was tested today (26 May at ~14:15 - 17:00 UT). All 14 LO channels are alive and show power levels at the detectors (mixers) consistent with previous on-ground measurements. No icing of the LO windows is apparent, as was considered a possibility from outgassing during launch, and no misalignment of the LO chains is apparent to within 1-2%.

The HIFI instrument is fully functional and will now start to be setup to work optimally for science operations.

[T. Marston from MOC ESOC, posted 26 May 2009]

Log: (05-24-2009)

2009-05-25T11:03:00.001-07:00

24 May 2009 (L+10, DOY 144)

PACS switch-on and initial functional tests

PACS has successfully been switched-on and passed the first activity in orbit, the so-called Short Functional Tests, on 24 May 2009. Results confirm that all mechanisms are moving on a very similar way than during the last ground test in Kourou, calibration sources are heated up, the sorption cooler is electrically functional. During a period of one hour the spectrometer's photoconductor arrays were fully operated, signal in the blue array is nominal, for the red array the spacecraft temperature conditions were still a bit high. Functional tests of the photometer's bolometer detectors have proven that we have no new "dead" pixels in any of the arrays.

In the coming days the bolometer's sorption cooler will be recycled before the acquisition of its first real optical signal and both spectrometer and photometer array settings will be fine tuned for in-orbit environment.

The PACS PI Albrecht Poglitsch reports "under the given boundary conditions of this phase of the mission and the scope of this test, our general impression is that things went as well as they possibly could have. Let's hope it will continue like this!"

[R.Vavrek from MOC ESOC, posted 25 May 2009]

Log: (05-22-2009)

2009-05-22T20:00:00.001-07:00

22 May 2009 (L+8, DOY 142)

Cool news! The first SPIRE helium-3 cooler recycling has been successfully performed today. The SPIRE PI Matt Griffin reports on behalf of the SPIRE consortium that the cooler was recycled manually with an as yet unoptimised procedure. Nevertheless a temperature of 293 mK was reached, making SPIRE - at least temporarily for now - the coldest known object in outer space!

[G. Pilbratt from ESTEC, posted 22 May 2009]

Log: (05-21-2009)

2009-05-22T19:58:00.000-07:00

21 May 2009 (L+7, DOY 141)

Following the switch-on of the SPIRE instrument, the first Herschel in-flight instrument data, 29 SPIRE Manual Commanding observations, were successfully processed by the Herschel Data Processing pipelines and ingested into the Herschel Science Archive. Achieving a flawless end to end processing and archiving with engineering observations, some of the most difficult observations to handle, is a great start for the Herschel ground segment.

[S. Ott from ESAC, posted 22 May 2009]

Picture of the Day #1

2009-05-22T09:49:00.000-07:00

Herschel is the only space facility dedicated to the submillimetre and far infrared part of the spectrum. Its vantage point in space provides several decisive advantages, including a low and stable background and full access to this part of the spectrum.
Herschel has the potential of discovering the earliest epoch proto-galaxies, revealing the cosmologically evolving AGN-starburst symbiosis, and unraveling the mechanisms involved in the formation of stars and planetary system bodies. The key science objectives emphasise specifically the formation of stars and galaxies, and the interrelation between the two, but also includes the physics of the interstellar medium, astrochemistry, and solar system studies.
Herschel will carry a 3.5 metre diameter passively cooled telescope. The science payload complement - two cameras/medium resolution spectrometers (PACS and SPIRE) and a very high resolution heterodyne spectrometer (HIFI) - will be housed in a superfluid helium cryostat.
Herschel will be placed in a transfer trajectory towards its operational orbit around the Earth-Sun L2 point by an Ariane 5 (shared with Planck) in early 2007. Once operational FIRST will offer a minimum of 3 years of routine observations; roughly 2/3 of the available observing time is open to the general astronomical community through a standard competitive proposal procedure.

Herschel and Planck commissioning has begun

2009-05-21T05:45:00.000-07:00

After a perfect injection by the Ariane 5 launcher on 14 May, the critical Launch and Early Orbit Phase (LEOP) for Herschel and Planck has started to wind down, while commissioning of the scientific instruments and subsystems on both spacecraft has begun.

Herschel and Planck are functioning nominally and are now en route to their final orbits around the second Lagrange point of the Sun-Earth system (L2), a point in space 1.5 million km from Earth on the night-side.

The additional ground stations that enabled near-continuous contact between mission controllers and Herschel and Planck during LEOP have been released; the two are now communicating via their nominally assigned stations, ESA’s New Norcia and Cebreros deep space stations, respectively.


	Ariane 5 V188 rises above ESA's Kourou tracking station

Shortly after launch, both spacecraft separated according to plan: Herschel at 15:37:55 CEST followed by Planck at 15:40:25 CEST. This triggered the execution of automatic sequences on board, including acquisition of the spacecraft’s orientation in space, configuration of the data handling system and switch-on of the high-frequency radio transmitters.

The first signals from both spacecraft were acquired by ESA’s New Norcia and Perth stations at 15:49 CEST. Shortly afterwards, telemetry was received confirming good health for both spacecraft. Both had acquired their nominal sun-pointing attitude and a telemetry check-out performed by the Mission Control Team confirmed their overall status as nominal.

Critical LEOP phase winding down

The operations planned for both spacecraft for the Launch and Early Orbit Phase have been completed successfully, and all time-critical procedures were completed on schedule or sooner than expected, including the SPIRE (Spectral and Photometric Imaging Receiver) launch lock release on Herschel and the activation of the HFI (High Frequency Instrument) 4K cooler on Planck.


	Herschel and Planck cruise to L2

The excellent injection provided by Ariane 5 into L2 transfer orbit means that only moderate trajectory correction manoeuvres (TCMs) – during which the thrusters are fired to change the spacecraft’s direction or speed - will be required giving ground controllers a larger margin of fuel for the scientific part of the mission.

On 15 May, both spacecraft successfully completed their first TCMs: TCM 1a for Herschel providing a change in speed of 8.7 m/s at 15:16:26 CEST, and TCM 1a for Planck providing a change in speed of 14.35 m/s at 20:01:05 CEST.

Subsystem commissioning began on 15 May for both satellites, and telescope and payload module cool-down started in parallel on both spacecraft.

Herschel

The telescope is cooling down fully in accordance with flight predictions to the decontamination temperature of 170K (-103°C). This ensures that the heaters stabilise the telescope temperature to keep contamination released from the spacecraft from freezing on the telescope mirrors. The cryostat is also cooling to its operational temperature and the critical helium phase separator is working perfectly. Commissioning of the spacecraft’s service module began on 15 May.


	Herschel's instruments

As planned, Herschel switched to reduced ground station coverage of 10 hrs/day on 16 May. This will continue until two weeks after launch for the initial commissioning activities. All of the satellite’s subsystems have shown nominal performance, and commissioning is in progress.

A touch-up manoeuvre was executed on 18 May at 19:00 CEST, providing a modest change in speed of 99 cm/s.

Planck

After the first TCM (1a), Planck’s trajectory was optimised based on the latest orbit determination. This first manoeuvre was very modest due to the excellent launch injection and was so accurate that no touch-up manoeuvre was required during LEOP; the planned TCM 1b was cancelled.


	Planck scanning the sky

The following manoeuvres will be the mid-course correction (manoeuvre 2) and the insertion manoeuvre (manoeuvre 3), scheduled for 5 June and 2 July at 19:00 CEST, respectively.

Another major milestone was completed with the commissioning of the ‘large’ slew capability. These slews, a few arc minutes in magnitude, are executed with small (1N) thrusters; they are large compared to the requirement for the mission. These large slews are necessary for Planck to follow its scanning strategy and recover fine control after monthly orbit maintenance manoeuvres performed with the bigger (20N) thrusters.

The HFI instrument has also been switched on and is fully functional. HFI is now waiting for the rest of the cooling chain to be switched on and to cool to its final operational temperature.

All of the satellite’s subsystems have been commissioned normally and ground station performance is nominal.

En route to L2

By 21:00 CEST on 19 May, Herschel and Planck were located 617 287 km and 607 767 km, respectively, from the Earth, approximately 1.6 times farther than the Moon's average distance of 384 403 km. The two sister satellites were separated by 9917.35 km.

Log: (05-20-2009 - 05-21-2009) Where is Herschel?

2009-05-21T05:43:00.000-07:00

20-21 May 2009 (L+6-L+7, DOY 140-141)

Where is Herschel?

Herschel is moving almost directly away from the Sun towards L2 and thus nearly directly away from us, so it does not move rapidly across the sky, even though it is still moving quite quickly through space. At midnight Universal Time (GMT) on launch day it was still going at an impressive 2.29km/s, having separated at 9.7km/s. Tonight, its speed has dropped to a more sedate 0.70km/s. At 699 000km distance signals now take 2.3 seconds to reach the satellite from Earth.

Based on the predicted orbit, Herschel will reach its greatest distance from Earth on the morning of July 7^th, when it will be at a distance of 2.28 million kilometers. From then on it will start to get closer again until September 5^th when it will have closed to a mere 1.25 million kilometres, finally settling into an orbit about L2 with a 6-month period.

Tonight Herschel is close to Right Ascension 16h17m, Declination -02° 35' in the constellation of Serpens Caput, about 3.5 degrees south of the magnitude 4.8 star Sigma Serpentis.

However, if you want to find Herschel, it is getting quite faint now, as it is getting close to magnitude 17. You can still see it though quite easily with a 20-cm telescope and a CCD, as the image below shows.

This image shows Herschel, Planck and the Sylda, observed from his back yard observatory in Lanzarote by the Argentinian amateur astronomer Gustavo Muler on the night of May 18/19^th, with a 30-cm telescope + CCD. The telescope tracked on the satellites, so you see the stars as long trails crossing the field of view. This image was composed of 80 exposures of 30 seconds each.

You can calculate an ephemeris for Herschel for your location in the JPL Horizons system: http://ssd.jpl.nasa.gov/horizons.cgi

Enter "Herschel Space Observatory" as the target name.

[M. Kidger from HSC ESAC, posted 20 May 2009]

Log: (05-19-2009 - 05-20-2009)

2009-05-21T05:42:00.000-07:00

19-20 May 2009 (L+5-L+6, DOY 139-140)

Herschel Switches On the First Science Instrument

Over the course of the last two days, the first instrument on Herschel has been successfully switched on. This is the SPIRE instrument, which has both a photometer and a FTS spectrometer. The full arrays were able to be switched on in both cases and all looked exactly as on the ground -- and possibly a bit better. No pixels in any of the arrays were lost. The original intention was to not attempt a full turn-on of the spectrometer, but the temperature conditions were suitable and the SPIRE team took advantage of this to check out the spectrometer at an early stage. Also tested were SPIRE's beam steering mirror, used for dithering or jiggling targets on the bolometer arrays, and the FTS spectrometer mechanism. All tests were successful.

SPIRE has further testing over the next few days before the other two instruments, PACS and HIFI are switched on -- on Sunday night.
Congratulations to SPIRE on their success so far!

[T. Marston from MOC ESOC, posted 21 May 2009]

NASA Contributions to the Herschel Space Observatory

2009-05-19T13:29:00.001-07:00

Through the Jet Propulsion Laboratory in Pasadena, California, NASA is contributing key technology to two of Herschel's three detector instruments: SPIRE and HIFI

Spectral and Photometric Imaging Receiver (SPIRE)

SPIRE will use "spider web bolometers", which are 40 times more sensitive than previous composite bolometers. They were developed by JPL's Dr. James Bock, SPIRE's Co-Investigator. In recognition of his innovation, Dr. Bock received the Presidential Early Career Award for Scientists and Engineers in March, 2002, the highest honor the U.S. government bestows on outstanding scientists and engineers who are beginning their independent careers.

Heterodyne Instrument for the Far-Infrared (HIFI)

HIFI will sense radiation along six wavelength bands. NASA is providing the mixers and local oscillator chains for the two highest bands, five and six; other local oscillator components for bands one through four; and power amplifiers.

NASA's Herschel Science Center

NASA also sponsors the NASA Herschel Science Center (NHSC), which provides the U.S. astronomical community with scientific and observational support throughout all phases of the Herschel mission. NHSC is operated by IPAC, the Infrared Processing and Analysis Center at the California Institute of Technology.

Herschel Science Instruments

2009-05-19T13:27:00.001-07:00

Science Instruments

The telescope will focus light onto three instruments: PACS and SPIRE, which each contain a photometer and low-to-medium resolution spectrometer, and HIFI, an extremely high-resolution heterodyne spectrometer.

They are designed for deep, wideband photometry (with high spatial resolution thanks to Herschel's large 3.5 meter mirror) and full spectral coverage, making Herschel the first space facility to completely cover the far infrared and submillimeter range. Together, PACS and SPIRE are capable of detecting light from 57-670 microns in wavelength. HIFI covers 480-1250 and 1410-1910 GHz (which corresponds to about 157-625 microns).

The three instruments are designed to compliment each other. SPIRE and PACS have imaging spectrometers that provide spatial information, while HIFI resolves with very high spectral resolution, but only one line at a time and in only one beam on the sky.

The emission lines of the main interstellar cooling agents are predominantly in the PACS range, but fall into the SPIRE wavelength range for very distant and hence highly redshifted objects. The combination of both instruments will provide the full range of information needed to determine SEDs (spectral energy distributions - the total amount of power radiated by cosmic objects, measured in watts), photometric redshifts, total luminosity, and accurate positions.

SPIRE and PACS will both conduct deep surveys with their photometers to find galaxies from the early Universe, and follow up with spectroscopic studies of the most interesting objects.

Keeping Cool

Observing light in that range means that Herschel will detect subtle "heat" emissions from very cold objects, such as vast clouds of interstellar dust. The spacecraft has to keep its instruments cold because their electronics work only at frigid temperatures, and to prevent the instruments' own infrared radiation from drowning out the faint signals they're trying to detect.

So the instruments are housed in a cryostat filled with more than 2,000 liters of superfluid helium. Based on technology developed for the Infrared Space Observatory (ISO), it will keep the instruments at a temperature of less than -271° Celsius, which is less then three degrees above absolute zero. The bolometers aboard PACS and SPIRE will be chilled even further, to -273.3° Celsius, just a few tenths of a degree above absolute zero.

Herschel Spacecraft Specs.

2009-05-19T13:16:00.000-07:00

The Herschel Space Observatory will be approximately nine meters high and 4.3 meters wide, with a launch mass of about 3.25 metric tons. It will consist of an infrared telescope, a payload module containing the instruments, and a service module that houses the warm electronics of the instruments, equipment for communicating with Earth, and other infrastructure.

Biggest Space Telescope

With a primary mirror measuring 3.5 meters in diameter, Herschel's Ritchey-Chr�tien telescope will be larger than any previous space-based telescope. Shielded from the sun, it will passively cool to around 80 K (80 degrees Celsius above absoulte zero) by radiating its heat into space.

The mirror will be made of silicon carbide, a lightweight ceramic material resistant to stress, fatigue, and extreme temperatures. It can be polished as if it were glass, deviating from perfect smoothness by no more than one micron - a requirement to avoid distorting the images it receives.

Revealing the invisible: Caroline and William Herschel

2009-05-19T13:13:00.000-07:00

Sir William Herschel discovered, in addition to the planet Uranus, many new nebulae, clusters of stars and binary stars. He was the first person to correctly describe the form of our Galaxy, the Milky Way. In 1800, the German-born British astronomer and musician described that the differently coloured filters through which he observed the Sun allowed different levels of heat to pass. He performed a simple experiment to study the

Credits: Royal Astronomical Observatory

Caroline Herschel, sister of Sir William Herschel. Pioneer in her own right in intrared studies.

Download:

HI RES JPG (Size: 912 kb)

Herschel's telescope will collect infrared radiation from distant stars.
Image shows telescope, vessel containing liquid helium cryostat (narrow, middle part), and service module at the bottom.

Credits: ESA 2002/Medialab

The Herschels were pioneers of the systematic classification and investigation of the heavens. William Herschel was one of the first 'professional' astronomers, and discovered infrared radiation. His sister Caroline helped him to develop the modern mathematical approach to astronomy.

William, son of a musician, was born in Hanover, Germany, in 1738. He followed in his father's marching footsteps, joining the Hanoverian Guard band to play the oboe. Herschel moved to England to become a teacher in 1755, eventually settling in Bath in 1766.

He became interested in astronomy, and started to build his own telescopes. He developed and refined the reflector design first suggested by Isaac Newton to avoid problems with poor glass optics. Herschel cast and polished his own mirrors, producing ever bigger and better telescopes.

In 1772, he invited Caroline to join him as an assistant in his musical business, and she moved to Bath too. Both enjoyed watching the skies and, in 1781, William discovered the planet Uranus. He named it briefly 'Georgium Sidus' in honour of the British King. The discovery of the new planet inspired Herschel to end his career as a musician and teacher and concentrate on astronomy. King George appointed William his private astronomer, and the Herschels moved to Slough, near Windsor, England.

By 1789, Herschel had built a 12-metre reflector, the largest telescope of its day. Meanwhile Caroline became the first woman to discover a comet, and discovered seven more in the years between 1786 and 1797, and then discovered three nebulae. In 1787 she was granted a salary of £50 by the King to act as her brother's assistant. Caroline worked hard in her own right, and in 1797 she published the 'Index to Flamsteed's Observations of the Fixed Stars' and a list of his mistakes.

After discovering moons around Saturn and Uranus, Herschel turned his attention from the planets to the stars, and drew up a catalogue of double stars that he showed were orbiting pairs. His paper 'On the Construction of the Heavens', published in 1784, modelled the formation of our Galaxy, the Milky Way, and marked the beginnings of Herschel's life-long interest in the cataloguing of the Universe.

In 1800, Herschel described that the different coloured filters through which he observed the Sun allowed different levels of heat to pass. He performed a simple experiment to study the 'heating powers of coloured rays': he split the sunlight with a glass prism into its different constituent rainbow colours and measured the temperature of each colour. He observed an increase in temperature as he moved a thermometer from the violet to the red part of the 'rainbow'.

Out of curiosity, Herschel also measured temperatures in the region just beyond the red colour where no light was visible and, to his surprise, he recorded the highest temperature there. He deduced the presence of invisible 'calorific' rays, now called 'infrared' radiation, and the reason why ESA's planned infrared observatory is named after him. Over the rest of his life, he produced lists of thousands of nebulae and star clusters, and he was the first to distinguish between distant clusters and dusty nebulae.

After William's death in 1822, Caroline returned to Hanover and re-organised his catalogues into one extensive book, for which she was awarded the Gold Medal of the Royal Astronomical Society, and was later elected a member, in 1828. An asteroid was named Lucretia in 1889 in her honour. This was a fitting tribute to someone who had contributed so much yet disliked the praise directed towards her if it detracted from her brother William.

The Herschels' work marked the first time that a new planet had been discovered with a mechanical aid, a telescope. Although the word had not yet been invented, the Herschels were among the first 'scientists', as distinct from natural philosophers. They were concerned with classification and orderings of the Universe, as opposed to discovering why things happen. Their approach to science was symbolic of a new style, following on from the experimental rationalism of Boyle and Newton.

Herschel at a glance

2009-05-19T13:12:00.000-07:00

Herschel at a glance

Herschel, ESA's cutting-edge space observatory, will carry the largest, most powerful infrared telescope ever flown in space. A pioneering mission to study the origin and evolution of stars and galaxies, it will help understand how the Universe came to be what it is today.

The first observatory to cover the entire range from far-infrared to sub-millimetre wavelengths and bridge the two, Herschel will explore further in the far-infrared than any previous mission, studying otherwise invisible dusty and cold regions of the cosmos, both near and far.

Herschel will tap into unexploited wavelengths, seeing phenomena out of reach for other observatories, at a level of detail that has not been captured before. The telescope's primary mirror is 3.5 m in diameter, more than four times larger than any previous infrared space telescope and almost one and a half times larger than that of the Hubble Space Telescope. The telescope will collect almost twenty times more light than any previous infrared space telescope.

The cutting-edge spacecraft carries three advanced science instruments: two cameras and a very high resolution spectrometer; their detectors are cooled to temperatures close to absolute zero by a sophisticated cryogenic system.

Primary mirror: 3.5 m in diameter.

Launch: May 2009 on board an Ariane 5 from ESA's Spaceport in Kourou, French Guiana. The launch window opens at 15:34:32 CEST. Herschel will be launched along with Planck, ESA's microwave observatory which will study the Cosmic Microwave Background.

Status: Preparations for launch under way.

Journey: Herschel will separate from the upper stage of the launcher about 26 minutes after launch, Planck will follow a few minutes later. The two spacecraft will operate independently. Two weeks from launch, Herschel will be more than 1 million km away from Earth and will begin commissioning. The observatory will reach its operational orbit about a hundred days after launch.

Orbit: Herschel will operate from a Lissajous orbit around the second Lagrangian point of the Sun–Earth system (L2), a virtual point located 1.5 million km from Earth in the direction opposite to the Sun. The satellite's average distance from L2 will be 800 000 km.

Lifetime: A minimum of three years for routine science observations. The mission will last until the cryostat runs out of helium, about four years after launch.

Instruments:
HIFI (Heterodyne Instrument for the Far Infrared), a high-resolution spectrometer; PACS (Photoconductor Array Camera and Spectrometer) and SPIRE (Spectral and Photometric Imaging REceiver), PACS and SPIRE are both cameras and imaging spectrometers. Together, these instruments cover 55–672 microns. Their detectors will be cooled to temperatures very close to absolute zero.

Launch mass: About 3.4 tonnes.

Dimensions: About 7.5 m high and 4 m wide.

Operations: Herschel will be operated as an observatory. About two-thirds of its observing time will be available to the worldwide scientific community. The rest of the observing time has been allotted to the instrument consortia. It will operate autonomously, sending acquired data to Earth over a three-hour period every day.

Primary ground station: ESA's deep space antenna in New Norcia, Australia.

Herschel Science Objectives

2009-05-19T13:11:00.000-07:00

Science objectives

Herschel is set to revolutionise our understanding of the Universe. A versatile infrared space telescope, Herschel's main objective is to study relatively cool objects across the Universe; in particular, the formation and evolution of stars and galaxies and the relationship between the two.

Within our Galaxy, the mission’s main science objectives are:

To study Solar System objects such as asteroids, Kuiper belt objects, and comets.
Comets are the best-preserved fossils of the early Solar System, and hold clues to the raw ingredients that formed the planets, including Earth.
To study the process of star and planet formation.
Herschel is unique in its coverage of a wide range of infrared wavelengths, with which it will look into star-forming regions in our Galaxy, to reveal different stages of early star formation and the youngest stars in our Galaxy for the first time. The telescope will also study circumstellar material around young stars, where astronomers believe that planets are being formed, and debris discs around more mature stars.
To study the vast reservoirs of dust and gas in our Galaxy and in other nearby galaxies.
Herschel will study in detail the physics and kinematics at work in giant clouds of gas and dust that give rise to new stars and associated planetary bodies. Herschel is also well-suited to study astrochemistry providing fundamental new insight into the complex chemistry of these molecular clouds, the wombs of future stars.

Outside our Galaxy, the mission’s main science objectives are:

To explore the influence the galactic environment has on interstellar medium physics and star formation. Most of what we have learned about the physics and chemistry of the interstellar medium, and of the processes there such as star formation, has been gained by studies in our own Galaxy. With Herschel, we can carry out similar studies in relatively nearby galaxies as well. For example, studies of nearby low- metallicity galaxies can open the door to the understanding of these processes in the early Universe.
To chart the rate of star formation over cosmic time. We know that star and galaxy formation commenced relatively early after the Big Bang. We also know that when the Universe was about half its current age, star formation was much more intense than it is today. Herschel is ideal to study infrared-dominated galaxies at the peak of star formation.
To resolve the infrared cosmic background and characterise the sources. About half the energy produced and emitted throughout cosmic history now appears as a diffuse infrared cosmic background. With its large telescope, Herschel will be able to resolve the far-infrared background and characterise its constituent sources to a degree never achieved before.

Herschel Highlights

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Herschel will carry the largest telescope ever flown in space, with a primary mirror 3.5 m in diameter.
The first space observatory to observe the entire range of wavebands from the far-infrared to submillimetre.
The highest sensitivity in its wavelength range.
It will cover unexploited infrared wavelengths allowing it to study the earliest stages in the life of a star that have not been observed by other telescopes, revealing the youngest stars in our Galaxy for the first time.
Herschel will feature the highest-ever resolution in the far infrared: it will be able to see detail never seen before.
The first observatory capable of studying the earliest stages of star formation.
Herschel will take the first census of star-forming galaxies throughout the Universe at the peak of star formation, allowing astronomers to chart the star formation history and evolution of galaxies in the Universe.
The first observatory to take a census of ongoing star formation in our galactic neighbourhood .
The most powerful tool to search for water throughout our Galaxy.

Space-based observations have never been performed in Herschel's main observing band, enlarging the mission's discovery potential. Given these unprecedented observing capabilities, the mission has tremendous discovery potential. As it opens new windows to the Universe, there is a good chance that Herschel will discover the unanticipated.

Herschel-Planck: Separation

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Watch Herschel-Planck launch 14 May 2009 15:12 CEST (replay)

2009-05-19T13:04:00.000-07:00

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Replay the Herschel and Planck launch. At 15:12:02 CEST, at the beginning of a 55-minute launch window, the Herschel and Planck satellite pair lifted off on board an Ariane 5 from Europe’s Spaceport in French Guiana.

Credits: ESA, 2009

ESA's cosmic explorers in flight: stunning images from ground and space

2009-05-19T13:03:00.001-07:00

The Planck-Sylda composite seen receding from Herschel after separation

15 May 2009
Stunning images taken from Earth and space show Herschel and Planck in flight on 14 May 2009. The first, taken from Herschel, show the Planck-Sylda composite just after Herschel's separation, about 1150 km above Africa. A second set taken from ESA's Optical Ground Station, shows Herschel, Planck, Sylda and the launcher’s upper stage long after separation, travelling together at an altitude of about

100 000 km.

This breath-taking animation comprises the first series of images taken by Herschel’s Visual Monitoring Camera (VMC) shortly after Herschel's separation at 15:38 CEST on 14 May.

The sequence clearly shows the Planck-Sylda composite receding behind Herschel, high above the surface of our planet; clouds, ocean and coastlines can be seen far below. The Sylda is a support structure that encapsulated Planck and supported Herschel during launch.

High above Africa

During this sequence, Herschel and the Planck-Sylda composite were travelling at an altitude of 1150 km above the East coast of Africa at a speed of almost 10 km/s. Planck separated from Sylda a few minutes later, at 15:40 CEST.

The second animation is composed of images taken by the telescope at ESA’s Optical Ground Station Station at Tenerife, Spain.

Satellites imaged by ESA's Optical Ground Station in Tenerife

The images were taken a few hours after separation starting at about 23:30 CEST. Four bright objects are clearly visible, three of them - Herschel, Planck and the Sylda - form a clear triplet moving in coordination in the centre. The fourth object is presumed to be the upper stage of the Ariane 5. They were travelling at an altitude of about 100 000 km.

Both of these sophisticated satellites were lofted into space on an Ariane 5 from Europe's Spaceport in Kourou, French Guiana, at 15:12 CEST, Thursday, 14 May 2009.

Almost 26 minutes later, about two minutes from each other, they set out on independent trajectories leading to their final orbit around the second Lagrange point of the Sun-Earth system, a virtual point in space, 1.5 million km from Earth in the direction opposite to the Sun. The Sylda will also travel to L2 on a separate trajectory.

Since the acquisition of the first radio signals from the two satellites at 15:49 CEST 14 May, they have been under control of ESA's European Space Operations Centre (ESOC), Darmstadt, Germany. Both satellites are operating in nominal condition on their way towards their final orbit around L2.

ESA's Herschel calls home using mobile phone technology

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ESA's Herschel calls home using mobile phone technology

19 May 2009
For the first time in spaceflight history, a satellite has used mobile phone technology to radio back to Earth. The transmission took place on 16 May when Herschel used the same technology as used in GSM mobile phone networks to send test data to ESA's deep space tracking station at New Norcia, Australia.

At 14:00 CEST on 16 May - just under two days after launch - Herschel switched its telemetry downlink to 'high rate mode' and began transmitting, marking the first-ever use of Gaussian Minimum Shift Keying (GMSK) modulation in space. GMSK is commonly used in Global System for mobile Communication (GSM) mobile phone networks due to its very efficient use of bandwidth and power.

"Herschel's 1.5-Mbps test transmission - roughly the same data rate provided by a home broadband Internet connection - was picked up at ESA's ESTRACK station at New Norcia, Australia, on Saturday, as the satellite was travelling some 280 000 km from Earth," said John Dodsworth, the Herschel-Planck Flight Operations Director speaking in the Main Control Room at ESOC, ESA's European Space Operations Centre, Darmstadt, Germany.


	New Norcia: ESA's first 35m deep space station

In a typical GSM mobile phone network, the same technology transmits data at a somewhat lower speed. Herschel's sister spacecraft Planck also uses GMSK technology, and its transmission capability will be tested later during the satellite's commissioning phase.

During their missions, the GMSK-based radio links will be used by both spacecraft to transfer data gathered by their scientific instruments and on-board subsystems, providing information on flight status and overall health.

Herschel's successful operational test confirms results obtained during mathematical simulations and ground tests conducted since 2001, when the GMSK implementation on Herschel and Planck was first planned.


	Plot showing Herschel's mobile phone call received at New Norcia station

The development was driven by the need to use bandwidth more efficiently in view of the growing number of ESA missions that require X-band communications via the Agency's deep space ground stations. Gaia, scheduled for launch in the 2011 timeframe, will also use GMSK-based communication.

The GSM standard is the most popular modulation standard for mobile phone networks in the world. According to the GSM Association, terrestrial GSM networks now cover more than 80% of the world's population in more than 212 countries and territories - and will soon extend 1.5 million kms further to L2, Herschel and Plank's final orbital destination.

Log: (05-18-2009)

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18 May 2009 (L+4, DOY 138)

The Herschel telescope decontamination heating is underway. It has been decided to prevent the Herschel telescope from cooling down to below 170 K for as long as possible compatible with opening the cryocover at a temperature of 120 K, where the cryocover opening date is determined by the needs of the science instruments. The secondary mirror (M2) is more exposed and cools more rapidly than the primary mirror (M1). Thus, having been tested on 17 May, at 06:13 (UT) on 18 May the M2 decontamination heating was started, while later the same day the M1 heating was briefly functionally verified (at the time the M1 temperature was about 187 K). The M1 heating will commence in the early hours of 20 May. The telescope heating will be discontinued about 6 days before cryocover opening to allow telescope cooldown.

A second, smaller, course correction manoeuvre was successfully performed on 18 May, with a target delta-V of 0.99 m/s.

[G. Pilbratt from ESTEC, posted 19 May 2009]

Log: (05-14-2009 - 05-17-2009)

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16-17 May 2009 (L+2-L+3, DOY 136-137)

Today I had occasion to record in the HSCOM log:

HSC essentially nominal. Quietest day for almost a year, as we wait for spacecraft checks to give way to more instrument activities. 2 Spacecraft (Herschel & Planck) crossing Lunar orbit. In the past 24 hours our Spitzer colleagues reported the exhaustion of their cryogen and we congratulated them on the end of their so-successful cold mission. Quite a special day!

[L. Metcalfe from HSC ESAC, posted 17 May 2009]

15-16 May 2009 (L+1-L+2, DOY 135-136)

Herschel operations are essentially nominal and the spacecraft continues to perform well. The first trajectory course correction was successfully carried out as planned about a day after liftoff on 15 May, injecting 8.7 m/s being within 1-2% of the planned magnitude, a small delta will be performed in a few days. On 16 May the spacecraft attitude control mode was successfully changed from thruster controlled mode to reaction wheel controlled mode.

The cooldown of the spacecraft follows the predictions. In particular this has been verified for the telescope which will be heated to stabilise its temperature at 170 K for an extended period (the heating will start on 18 May), and the cryostat which will reach maximum superfluid helium temperature of just under 2 K on 18 May and maximum mass flow of just under 15 mg/s on 19 May.

[G. Pilbratt from CSG Kourou, posted 17 May 2009]

14 May 2009 (Launch date, DOY 134)

Herschel was launched together with Planck on flight V188 on an Ariane 5 ECA on 14 May 2009 from CSG Kourou, the liftoff took place at 13:12:02 UT, at the very beginning of the launch window. The launch itself was flawless, and Herschel separated from the launcher at 13:37:55 UT, just under 26 mins after lift-off.

The spacecraft was acquired by the New Norcia ground station at 13:49 UT, and good telemetry was received shortly afterwards. The spacecraft was confirmed to have acquired nominal attitude and overall status was confirmed nominal. The uplink was established and the first command was executed at 14:10 UT.

Already before even separating from the launcher, a major milestone had been achieved. The helium subsystem is working according to the book, both the large and small nozzles are open, and there is positive confirmation that the phase separator is working nominally. Together with a helium temperature at launch of only 1.81 K, this is good news regarding the cryo subsystem.

The launcher performance was very good, and the preliminary assessment of the orbit is: perigee 270.0 km (intended 270.0 ± 4.5), apogee 1,197,080 km (intended 1,193,622 ± 151,800), inclination 5.99 deg (intended 6.00 ± 0.06); or in plain english: spot on.