Herschel overview



Status
In development

Objective
Exploring formation of stars and galaxies, ESA’s Herschel space observatory (formerly called Far Infrared and Submillimetre Telescope, or FIRST) will solve the mystery of how stars and galaxies are born.

Mission


Image shows telescope, vessel containing liquid helium cryostat (narrow, middle part),
and service module at the bottom.

Credits: ESA 2002. Illustration by Medialab.

Herschel will be the largest space telescope of its kind when launched. Herschel’s 3.5-metre diameter mirror will collect long-wavelength infrared radiation from some of the coolest and most distant objects in the Universe. Herschel will be the only space observatory to cover the spectral range from far-infrared to sub-millimetre wavelengths.

Infrared radiation is invisible for the human eye. It is actually 'heat', or thermal radiation. Even objects that we think of as being very cold, such as an ice cube, emit infrared radiation. For this reason, infrared telescopes can observe astronomical objects that remain hidden for optical telescopes, such as cool objects that are unable to emit in visible light.

Also, infrared instruments need to be cooled down to temperatures below -271°C, otherwise their own infrared emission would spoil the observations. Opaque objects, those surrounded by clouds of dust, are another speciality for infrared telescopes: the longer infrared wavelengths can penetrate the dust, allowing us to see deeper into such clouds.

However, Earth's atmosphere acts as an 'umbrella' for most infrared wavelengths, preventing them from reaching the ground. A space telescope is needed to detect this kind of radiation invisible to the human eye and to optical telescopes.

What's special?

If it was possible to look at the Universe from the outside it would probably appear as a foamy structure, with the galaxies distributed in curved walls surrounding huge areas of emptiness, like bubbles in a foam bath. Such is the overall picture of the present-day Universe.

However, it was not always like that. There was a time when galaxies were not there, simply because they did not even exist yet. Astronomers have several questions about this time. When did galaxies form? How did it happen? Did they all form at about the same time, or is there a non-stop galaxy-making machine at work? Were the first galaxies like those we see now? The galaxies are made of stars... Did the stars form first and then get together to form galaxies, or was it the other way round? How do stars form? When they form, do they normally form planets as well?

Astronomers dream of a telescope able to answer these kinds of questions. They want a telescope that fulfils at least two requirements. It has to be a giant space telescope, able to collect light from very distant galaxies. Secondly, it must be able to observe objects completely enshrouded by dust, as forming stars and galaxies are certainly dusty.

ESA's Herschel mission has been designed specifically to achieve these goals. With its ability to detect far-infrared light, it will let astronomers see, for the first time, dusty and cold regions that have been hidden so far. With its 3.5-metre mirror, Herschel will mark the beginning of a new generation of 'space giants'.

Spacecraft and telescope

The Herschel satellite is approximately 7 metres high and 4.3 metres wide, with a launch mass of around 3.25 tonnes. It will carry the infrared telescope and three scientific instruments. The bulk of the spacecraft consists of a liquid helium thermos bottle inside which the instrument detectors sit and are cooled down to only a few degrees above absolute zero.

The Herschel spacecraft will be built by an industrial consortium led by Alcatel in Cannes, France, with EADS Astrium in Friedrichshafen, Germany, and Alenia in Torino, Italy, as the main subcontractors, and more subcontractors all over Europe.

The telescope is a Cassegrain telescope, with a primary mirror diameter of 3.5 metres. This is the largest space telescope ever to be built and a great technological challenge that Europe will face alone. The contract signed between ESA and EADS Astrium in Toulouse, France, to build Herschel's telescope makes it fully European.

Herschel's telescope has to meet demanding requirements. It has to be light enough to be placed into an orbit far more distant than, for example, that of Hubble: Herschel will be orbiting at a point called L2, 1.5 million kilometres away, about four times the distance from Earth to the Moon.

Also, the mirror's surface has to be extremely smooth; it must be polished to make it so uniform that its 'bumps' are smaller than a few thousandths of a millimetre. It will have to withstand very hard environmental conditions. At launch, it will be 'shaken' with a force several times that of normal gravity on Earth. In space, it will go through extreme temperature changes - from ambient temperature at launch to an average of -200°C.

Science payload

Engineers designed Herschel's science payload and optimised it with the prime science goals in mind. Moreover, it offers a wide range of capabilities for the 'general' observer. It consists of three instruments:

• Photodetector Array Camera and Spectrometer (PACS) instrument will be built by a consortium led by MPE, Garching, Germany.
• Spectral and Photometric Imaging REceiver (SPIRE) instrument will be built by a consortium led by University of Cardiff, United Kingdom.
• Heterodyne Instrument for the Far Infrared (HIFI) instrument will be built by a consortium led by SRON, Groningen, The Netherlands.

PACS and SPIRE are cameras and spectrometers that will allow Herschel to take pictures in six different ‘colours’ in the far-infrared. HIFI is a spectrometer with extremely high resolution. The scientific payload complement was approved by the ESA in February 1999.

Journey

Herschel will be launched in 2007 with another mission, Planck - a mission to study the cosmic microwave background radiation - on an Ariane rocket. The two spacecraft will separate soon after launch and will operate independently. Herschel will travel to an orbit beyond the Moon around a point known as the second Lagrangian point (L2).

Herschel has an operational lifetime of three years minimum. It potentially offers about 7000 hours of science time per year. It is a multiuser observatory accessible to astronomers from all over the world.

History

The main scientific emphasis, mission requirements, and technological needs for Herschel (or FIRST as it was then called) were discussed for the first time in the early 1980s. In 1983, the United States-Dutch-British IRAS satellite inaugurated infrared space astronomy by mapping 250 000 cosmic infrared sources and large areas of extended emission.

In November 1995, ESA launched its Infrared Space Observatory (ISO) which has allowed a much closer look, a more detailed perception of the 'infrared scenery'. In August 2003, NASA launched the Spitzer Space Telescope (formerly Space Infrared Telescope Facility, SIRTF), a space-borne, cryogenically cooled infrared observatory. This is still currently operating.

As ESA's fourth Cornerstone mission, Herschel has been planned to build on and extend the successes of these earlier missions by offering a much larger telescope and being the first to extend the spectral coverage down into the far-infrared and sub-millimetre wavelengths.

Source: ESA - Space Science - Herschel

Artist's impression of ESA's Herschel satellite, designed to study
the formation of galaxies and stars. It is due for launch in mid
2008, in couple with the ESA Planck satellite that will map the
Cosmic Microwave Background (CMB) to study the early of the
Universe.

Credits: ESA/AOES Medialab

6 December 2006
ESA’s Herschel spacecraft is proceeding towards its industrial completion. The satellite’s service module has passed its assembly and verification tests, and is now ready to move towards its final integration and test phases.

The service module is the satellite platform on top of which the ‘payload module’ - containing the cryostat with the science instruments and the telescope - will be mounted.

The Herschel satellite will carry the largest telescope mirror ever flown in space. It will operate in the infra-red and sub-millimetre wavelengths, to study the formation of stars and galaxies.

After its assembly by the Alcatel Alenia Space teams in Turin, Italy, the service module successfully passed the verification phase, and is now ready to be delivered to Astrium Satellites for final satellite assembly. The complete satellite will then be submitted to environmental acceptance tests in the ESA facilities located at ESA's European Space Research and Technology Centre (ESTEC), The Netherlands.

The Herschel satellite is planned for launch in mid 2008, on board an Ariane-5 rocket, together with the Planck satellite, the ESA astronomy mission designed to accurately measure the Cosmic Microwave Background Radiation that carries information about the early Universe.


Note

The development of the Herschel and Planck satellites, and all support activities prior to their launch, are provided by Alcatel Alenia Space, the industrial Prime Contractor selected by ESA, leading a consortium of more than 30 companies. Both spacecraft's service modules are equipped with state of the art avionics, power distribution, communication, attitude control and propulsion subsystems, and they have been developed over a time span of 5 years.

Source: ESA - Space Science - Herschel

Top view of the Herschel cryostat in the Large Space Simulator, where it is being prepared
for a three week test in in ESA's ESTEC facilities, Noordwijk (Netherlands). The tests
took place between the end of January and mid February 2007.

Credits: ESA

21 February 2007
The heart of ESA's infrared space telescope, Herschel, has successfully completed a vital round of tests. The cylindrical cryostat will now be loaded with the spacecraft's instruments before more tests and Herschel’s eventual launch in 2008.

Herschel's cryostat is a complex vacuum flask, 2.5 metres high and 2 metres wide. It is vital to the mission because Herschel's instruments need a temperature of 1.7 Kelvin (–271.3 degrees Celsius) to operate within their most sensitive range. The instrument surroundings must equally be very cold, to enable Herschel to see to see the infrared emission from cool matter in the Universe. If the cryostat and instruments reach higher temperatures they will emit infrared, overwhelming that from the celestial objects.


Herschel cryostat being prepared for a three week test inside the Large Space Simulator,
in ESA's ESTEC facilities, Noordwijk (Netherlands). The tests took place between the
end of January and mid February 2007.

Credits: ESA

Herschel must sit in the full glare of the hot Sun because it uses a solar panel to turn sunlight into electrical power. The cryostat is therefore essential to cool the instruments. The cryostat sits behind the solar panel, isolated from it by several layers of insulation, and contains two tanks that will be filled with liquid helium.

The first procedure in the just completed cycle of tests was the 'bake out'. In this process, the empty cryostat was heated to 80 degrees centigrade. Heating drives out any volatile substances including any residual water left inside the cryostat. Water reduces the quality of the insulation so its removal is vital to the lifetime of the cryostat. "In effect, the bake out cleans the cryostat," says Thomas Passvogel, Herschel's Project Manager.


This artist's concept shows the Herschel spacecraft.

Herschel will be the largest space telescope ever launched to
date. Its 3.5-metre diameter mirror will collect long-wavelength
infrared radiation from some of the coolest and most distant
objects in the Universe. Herschel will be the only space
observatory to cover the range from far-infrared to sub-millimetre
wavelengths.

The mission will be launched in July 2008, in tandem with ESA's
Planck spacecraft, by an Ariane-5 from Europe's Spaceport in
Kourou (French Guiana).

Credits: ESA

Next, the engineering team simulated the launch campaign. The cryostat was cooled down and the tanks were filled with liquid helium just as they will be five days before launch. The main tank holds 2250 litres of superfluid helium. The small tank is used to extend the ground 'hold' time of the system. The team monitored the helium temperature increase in the main tank, while cooling the cryostat with helium evaporating from the small tank. Every second day, they topped-up the small tank.

When they do this for real, at the launch site in Kourou, French Guiana, the cryostat will be able to withstand a launch delay of one day before the temperature in the main tank gets too high to launch safely. If the delay is any longer, the rocket will be rolled back to the assembly building and the engineers will have to recondition the main tank, refill it and subcool it.

The final tests in the current round were to monitor the behaviour of the cryostat with the outer vessel at ambient temperature; then to load it into the Large Space Simulation chamber at the European Science and Technology Centre (ESTEC) and monitor it again, this time under the conditions that Herschel will find in space. "We need these two extremes so that we can correlate computer models to predict what will happen inside the cryostat between launch and when it cools to its final operating temperature," says Passvogel.

Now that Herschel’s cryostat has passed all these tests and supplied excellent data for the team, the task of placing the instruments inside must begin. Then there will be more tests, in preparation for the July 2008 launch.

Source: ESA - Space Science - Herschel

The Herschel telescope's primary mirror will be the largest ever launched in space. In
this photo, it is being coated with a thin aluminium cover, which is the working surface
of the telescope, in the vacuum chamber at Calar Alto Observatory, Spain.

Credits: EADS Astrium/ P. Dumas

2 March 2007
Hundreds of astronomers met at ESA’s European Science and Technology Centre (ESTEC) in the Netherlands on 20-21 February 2007 to make plans for using Herschel, ESA’s large Infrared Space Telescope due for launch in July 2008. With the largest mirror ever to be flown in space, Herschel will change forever the way astronomers see the infrared Universe.

Herschel’s mirror is fully 3.5 metres in diameter: twice the size of any previous infrared telescope. It is even one and a half times larger than the optical Hubble Space Telescope. Its three high-precision instruments will detect far-infrared radiation from cool objects in the Universe. These will often be still-forming stars, surrounded by cool cocoons of dust and gas, either in star forming regions in our own galaxy or as starburst galaxies.


This beautiful and unusual view of the M16 nebula, also known as 'The Eagle', was built
thanks to data collected by ESA's Infrared Space Observatory (ISO). It shows exactly
what in the best known pictures of this famous nebula remains invisible: huge amounts
of the cold dust that enshrouds newborn stars.

Building upon ISO's heritage, ESA's Herschel spacecraft, to study the Universe at infrared
and sub-millimitre wavelenghts, will peer into the secrets of star formation with state-of-
the-art technologies.

Credits: Photo: ESA/ISOGAL team

“Star formation is central to everything that Herschel will do,” says Göran Pilbratt, Herschel Project Scientist. The Herschel science programme can be split into three broad strands.

Firstly, Herschel will study the formation and evolution of galaxies when the Universe was roughly half its present age. This is the era when most of the stars in the Universe were forming.

Secondly, Herschel will target star and planet formation, and the subsequent stellar evolution. It will look at the details of how stars form, the environment from which they form and the way they enrich their environment when they die.


Among its objectives, Herschel will target star and planet formation and evolution. It
will look at the details of how stars form, the environment from which they form and
the way they enrich their environment when they die.

Herschel will chart the build-up of heavy elements in the Universe. Called metals by
astronomers, these chemical elements are everything heavier than hydrogen and
helium.

Credits: AOES Medialab

This work will allow Herschel to chart the build-up of heavy elements in the Universe. Called metals by astronomers, these chemical elements are everything heavier than hydrogen and helium. In the present day, they make up just two percent of the atoms in the Universe. Shortly after the big bang, they were non-existent. They are created in the hearts of stars and scattered into space when the stars die. “Without these elements, there would be no planets or life,” says Pilbratt, “We are literally made of stardust.”

Thirdly, Herschel will look at the primitive bodies in our Solar System. These are the comets and outer solar system bodies. Together they represent fragments left over from the formation of the planets and may hold important clues as to how the Solar System formed.


Artist's impression of ESA's Herschel satellite, designed to study
the formation of galaxies and stars. It is due for launch in mid
2008, in couple with the ESA Planck satellite that will map the
Cosmic Microwave Background (CMB) to study the early of the
Universe.

Credits: ESA/AOES Medialab

Herschel will have a scientific lifetime of three years. After that, the liquid helium that cools the spacecraft to its working temperature will be depleted and the spacecraft will become too warm. It is therefore essential to achieve the very best use of the spacecraft’s working lifetime.

An Announcement of Opportunity was issued on 1 February asking the scientific community for ‘Key Programmes’ to be proposed. These must satisfy three requirements: they must exploit Herschel’s unique capabilities to address important scientific issues in a comprehensive manner; they must require a large amount of observing time to be used in a uniform and coherent fashion; and they must produce datasets of high archival value.

At the two-day workshop at ESTEC, the scientists in the Herschel Science Centre who are preparing Herschel’s scientific operations met the space telescope’s potential users to help them prepare for the observatory. The workshop contained poster sessions, in which astronomers presented the observations that they would like to make with Herschel. “People were extremely open about what they wanted to do with Herschel. There was a lot of discussion,” says Pilbratt.

The Key Programmes will allow Herschel to build a detailed archive of infrared observations, tailored to the needs of the astronomical community. This means that Herschel will provide a legacy to astronomers that extends for many years after the observational phase of the mission is over.

Source: ESA - Space Science - Herschel

Artist's impression of ESA's Herschel satellite, designed to study
the formation of galaxies and stars. It is due for launch in mid
2008, in couple with the ESA Planck satellite that will map the
Cosmic Microwave Background (CMB) to study the early of the
Universe.

Credits: ESA/AOES Medialab

4 September 2007
ESA PR 27-2007. By the end of 2007, the assembly of the ESA’s Herschel far-infrared space observatory – the latest mission to study the formation and evolution of stars and galaxies – will be completed.

ESA and Astrium are jointly inviting the media to a press conference in Friedrichshafen, Germany, on 19 September 2007, to hear about this revolutionary spacecraft, its scientific objectives, and to view the very heart of its hardware.

The Herschel mission, equipped with the largest telescope ever launched in space (3.5 m diameter), will give astronomers their best capability yet to explore the universe at far-infrared and sub-millimetre wavelengths. By measuring the light at these wavelengths, scientists see the ‘cold’ universe. Herschel will give them an unprecedented view, allowing them to see deep into star forming regions, galactic centres and planetary systems.

In order to achieve its objectives and to be able to detect the faint radiation coming from the coolest objects in the cosmos, otherwise ‘invisible’, Herschel’s detectors must operate at very low and stable temperatures. The spacecraft is equipped so as to cool them close to absolute zero (-273.15 ºC), ranging from -271 ºC to only a few tenths of a degree above absolute zero. To have achieved this particular feature alone is a remarkable accomplishment for European industry and science.

The final integration of the various components of the Herschel spacecraft – payload module, cryostat, service module, telescope and solar arrays – will be completed in the next few months. This phase will be followed by a series of tests to get the spacecraft ready for launch at the end of July 2008. Herschel will be launched into space on an Ariane 5 ECA rocket. The launch is shared with Planck, ESA’s mission to study relic radiation from the Big Bang.


Note

The Prime Contractor for the Herschel spacecraft is Thales Alenia Space (Cannes, France). It leads a consortium of industrial partners with Astrium (Germany) responsible for the Extended Payload Module (EPLM, including the Herschel cryostat), Astrium (France) responsible for the telescope, and the Thales Alenia Space industry branch of Torino, Italy, responsible for the Service Module (SVM). There is also a host of subcontractors spread throughout Europe.

The three Herschel instruments were designed and built by consortia of scientists and institutes, with their own national funding. The Photodetector Array Camera and Spectrometer (PACS) was developed under the coordination of the MPE, Germany; the Spectral and Photometric Imaging Receiver (SPIRE) was developed under the coordination of the Cardiff University (United Kingdom); the Heterodyne Instrument for the Far Infrared (HIFI) was developed under the coordination of the SRON institute (The Netherlands).


For more information

ESA Media Relations Office
Tel: +33(0)1.53.69.7299
Fax: +33(0)1.53.69.7690


Herschel Press Day
at Astrium, Friedrichshafen, Germany
19 September 2007
Claude-Dornier-Strasse
88090 Immenstaad

Source: ESA - News

After reading your thread on the Akari satellite and finding out they plan another mission, it seemed interesting to compare a few related missions.


HST has a 2.4 meter primary mirror (silica glass).
NICMOS (if it still works) uses neon filled cryo-pump for < 75 K.

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Spitzer has an 85 cm. primary mirror (beryllium).
Superfluid helium II croysat cools science instruments to < 1.4 K.
3.6 - 160 microns

---

Akari's primary mirror was 70 cm (beryllium).
Mission was to make survey-type observations at 50 -180 microns.
They also used an InfraRed Camera for 1.7- 26.5 microns.

Their next mission is-

SPICA (after Akari) will have a 3.5 meter primary mirror (silicon carbide).
Cryo cooled to 1.7 K.
Future mission will study 5-200 microns.
Launch 2015.

---

Herschel Space Telescope has a 3.5 meter primary mirror (silicon carbide).
Superfluid helium II croysat will cool science instruments to 1.7 K.
Mission is to study 60-670 microns.

HIFI: Heterodyne Instrument for the Far-Infrared
High Resolution Spectrometer In Two Bands
157 - 211 and 240 - 625 microns

PACS: Photo-Array Camera and Spectrometer
Camera and Spectrometer
57 - 210 microns

SPIRE: Spectral and Photometric Imaging Receiver
Camera and Low Resolution Spectrometer
200 - 670 microns

---

Next Generation Space Telescope- 6.5 meter primary mirror (beryllium) .
Solid hydrogen cryo-cooler-
includes a Pulse Tube precooler gets the instrument down to 18K
and a Jules-Thomson Loop heat exchanger knocks it down to 7K.

Mid-Infrared Instrument (MIRI) imager/spectrograph
5 - 27 microns

Near Infrared Camera (NIRCam) large field of view and high angular resolution.
0.6 - 5 microns

The Near Infrared Spectrograph (NIRSpec)
9-square-arcminute field of view simultaneous medium-resolution spectra of
100 objects at 1 - 5 microns; or lower-resolution spectra from 0.6 - 5 microns

Herschel will be the largest space telescope ever launched to date. From a point in space called the 2nd Lagrangian Point (or L2), its 3.5-metre diameter mirror will collect long-wavelength infrared radiation from some of the coolest and most distant objects in the Universe. Herschel will be the only space observatory to cover the range from far-infrared to sub-millimetre wavelengths. The mission is to be launched in July 2008, in tandem with ESA's Planck spacecraft, by an Ariane-5 rocket from Europe's Spaceport in Kourou (French Guiana).

Credits: ESA/ AOES Medialab

19 September 2007
Herschel, Europe’s infrared space observatory is being presented to the media today in a joint press event by ESA and Astrium in Friedrichshafen, Germany. Two of the satellite’s most fundamental modules, its ‘heart’ and ‘brain’, have now been mated.

The far-infrared space observatory is ESA’s latest mission that will study the formation and evolution of stars and galaxies. Herschel will carry the largest telescope ever flown in space, giving astronomers their best view yet of the cold and most distant objects in the universe. It will collect very long infrared wavelengths, peeking into star-forming regions, galactic centres and planetary systems.

To protect the sensitive instruments from heat generated during operations and to achieve its challenging objectives, the satellite must operate at very low temperatures. This is why the spacecraft’s brain – or its payload module – hosts a cryostat, a cryogenic module inside which the cold components of the scientific instruments are mounted.

Inside the cryostat the sensitive instrument detectors are cooled down to about -273 ºC (0.3 degrees above absolute zero). This low temperature is achieved using superfluid helium (at about -271 ºC) and an additional cooling stage inside the focal plane units.

The service module is the spacecraft’s heart, which keeps the spacecraft going by caring for all its vital functions. It also carries the ‘warm’ components of the instruments – those that do not require cooling with the cryostat.

Between late July and early August this year, the cold and warm units of the instruments were mated with the cryostat and the service module respectively.

Last week, on 11 September, the cryostat containing the cold instrument units was finally mounted on the service module, mating Herschel’s heart and brain.

This picture was taken on 11 September during the mating of Herschel's cryostat (an important part of the payload module) and the service module at Astrium's facilities in Friedrichshafen. All that is now left to complete the spacecraft is the solar array and its telescope.

The cryostat contains the sensitive instrument detectors cooled down to about -273ºC (0.3 degrees above absolute zero). The service module is the spacecraft’s heart, which keeps the spacecraft going by caring for all its vital functions. It also carries the ‘warm’ instrument units – those that do not require cooling with the cryostat.

Between late July and early August this year, the cold and warm units of the instruments were mated with the cryostat and the service module respectively.

On 11 September, the cryostat containing the cold instrument units was finally mounted on the service module, mating Herschel’s heart and brain.

This fundamental step will be followed by functional and compatibility testing at Astrium before the spacecraft is sent to ESA’s European Space Research and Technology Centre (ESTEC) in November for final environmental (thermal, mechanical, acoustic) and functional acceptance tests.

In late December 2007 or early 2008, after the functional tests, the telescope and the solar arrays – two other fundamental parts of the payload module - will be mated to the rest of the spacecraft, completing Herschel.

Credits: Astrium (M. Pikelj)

This fundamental step will be followed by functional and compatibility tests at Astrium before the spacecraft is sent to ESA’s European Space Research and Technology Centre (ESTEC) in November for final environmental (thermal, mechanical, acoustic) and functional acceptance tests.

In late December 2007 or early 2008, after the functional tests, the telescope and the solar arrays – two other fundamental parts of the payload module - will be mated to the rest of the spacecraft, completing Herschel.

Herschel is scheduled to launch from Europe’s spaceport at Kourou in French Guiana on 31 July 2008, on an Ariane 5 ECA launch vehicle. The launch will be shared with Planck, ESA’s mission that will study relic radiation from the Big Bang.

Take a look at the latest multimedia on Herschel

Note:

This picture shows an artist's impression of the view inside Herschel.

To protect the sensitive instruments from heat generated during operations and to achieve its challenging objectives, the satellite must operate at very low temperatures. This is why the spacecraft’s brain – or its payload module – hosts a ‘cryostat’, a cryogenic module inside which the cold components of the scientific instruments are mounted.

Inside the cryostat the sensitive instrument detectors are cooled down to about -273 ºC (0.3 degrees above absolute zero). This low temperature is achieved using superfluid helium (at about -271 ºC) and an additional cooling stage inside the focal plane units.

The service module is the spacecraft’s heart, which keeps the spacecraft going by caring for all its vital functions. It also carries the ‘warm’ components of the instruments – those that do not require cooling with the cryostat.

Credits: ESA/ AOES Medialab

The Prime Contractor for Herschel is Thales Alenia Space (Cannes, France). It leads a consortium of industrial partners with Astrium (Germany) responsible for the Extended Payload Module (EPLM, including the Herschel cryostat), Astrium (France) responsible for the telescope, and the Thales Alenia Space industry branch of Torino, Italy, responsible for the Service Module (SVM). There is also a host of subcontractors spread throughout Europe.

The three instruments on Herschel were designed and built by consortia of scientists and institutes, with their own national funding. The Photodetector Array Camera and Spectrometer (PACS) was developed under the coordination of the MPE, Germany; the Spectral and Photometric Imaging Receiver (SPIRE) was developed under the coordination of the Cardiff University, United Kingdom; and the Heterodyne Instrument for the Far Infrared (HIFI) under the coordination of SRON, Netherlands Institute for Space Research.


For more information:

Thomas Passvogel, ESA Herschel Project Manager Email: Thomas.Passvogel @ esa.int

Göran Pilbratt, ESA Herschel Project Scientist
Email: Gpilbratt @ rssd.esa.int








This is an image of the Heterodyne Instrument for the Far Infrared's (HIFI) focal plane unit. Clearly visible are 7 of the 14 mixer sub-assemblies, in which the signal received by the telescope is mixed with the signal generated by the local oscillator.

HIFI is a very high-resolution heterodyne spectrometer. The heterodyne detection principle involves translating the frequency range of the astronomical signal being observed to a lower frequency where it is easier to perform the required measurements.

This is done by mixing the incoming signal with a very stable monochromatic signal, generated by a local oscillator, and extracting the difference frequency for further processing.

HIFI observes in seven bands covering 480 to 1910 gigaHertz.

Credits: SRON


The Photoconductor Array Camera and Spectrometer (PACS) contains a camera and low to medium resolution spectrometer. It operates at wavelengths between 55 and 210 micrometres.

The opening of this infrared window by PACS to sensitive photometry and spectroscopy at high spatial resolution will address a wide range of key questions of current astrophysics concerning the origins of stars, planetary systems, galaxies, and the evolution of the Universe.

Credits: Max-Planck-Institut für extraterrestrische Physik


The Spectral and Photometric Imaging Receiver (SPIRE) comprises a three-band imaging photometer and an imaging Fourier transform spectrometer. The instrument will be used to undertake large area deep sky photometric imaging surveys and allow follow-up spectroscopic observations of selected sources.

These observations will help tackle two of the most fundamental questions in astronomy: how and when did galaxies form and how do stars form?

Credits: SPIRE Consortium

Source: ESA - News