Mission completed for Herschel [fr]

End of the Herschel mission, the largest astronomical space telescope

Launched by Ariane 5 on May 14th, 2009, the lifespan of the European Space Agency’s Herschel space observatory was limited by its supply of liquid helium that served as coolant for its scientific instruments. This supply ran dry on Monday, April 29th, 2013, ending Herschel’s operations just two weeks before its fourth anniversary in service.
This telescope, set at our solar system’s L2 Lagrange point, provided us with incredible information about the birth of stars, the evolution of galaxies and of interstellar matter, and our solar system. Initially intended to function for a period of three and a half years, Herschel has recorded more than 25 000 hours of data for 600 observation programs.
Herschel studied the cold and distant universe. It studied the chemical composition of a very wide range of environments, of the cocoons of stars at the heart of galaxies and comets. There have been more than 600 scientific articles based on discoveries made using Herschel’s data.

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Composite image of findings from PACS (blue) and SPIRE (red) in the W3 region of our galaxy. Filamentary structures are visible (labelled “east loop” and “west loop”). (© ESA/Herschel/PACS&SPIRE) © ESA/Herschel/PACS&SPIRE
Meet Herschel

Named for German-British astronomer William Herschel, whose notable achievements include the discovery of Uranus, the Herschel space observatory is the largest spatial telescope dedicated to infrared and submillimeter astronomy. It has enabled researchers to make a number of technological advances thanks to its revolutionary design: a cryostat cooling system, the largest mirror (3.5m in diameter) ever built for spatial astronomy, and three measurement instruments:
• HIFI (Heterodyne Instrument for the Far-Infrared), a high-resolution spectrometer designed to study the chemical makeup of the universe;
• PACS (Photoconductor Array Camera and Spectrometer), a photometer used to map infrared emissions in interstellar space and a spectrometer to study their chemical and physical states; and
• SPIRE (Spectral and Photometric Imaging REceiver), which accomplishes much of the same functions as PACS, but on larger wavelengths of submillimetric infrared.
The fabrication techniques developed for Herschel have already been applied to the next generation of the ESA’s space missions, particularly the Gaia mission.

Fruitful space exploration

“Herschel has offered us a new view of the hitherto hidden Universe, pointing us to a previously unseen process of star birth and galaxy formation, and allowing us to trace water through the Universe from molecular clouds to newborn stars and their planet-forming discs and belts of comets”, says Göran Pilbratt, Herschel Project Scientist at the ESA.
This mission has given us mind-blowing images of stars and galaxies, telling the entire story behind the formation of stars, thanks to its ability to detect temperature variations of only a few degrees Kelvin above absolute zero (-273°C). It has tracked the original states of distant galaxies from the earliest days of the universe, 13.8 billion years ago. It has discovered supergalaxies with more than several times the stellar production capabilities of our own galaxy, the Milky Way.
Herschel also allowed us to detect massive quantities of water in clouds of stellar dust, in the discs of forming planets and in the comet Hartley-2. As a result, it reopened the debate about the cosmic origins of water on Earth as the result of bombardment of ice-encrusted comets. This led scientists to comb space for proof.

Herschel’s track record

In light of the six-month extension to its four-year operational life (+15%) and the 600 documents published based on its data to date—not to mention those to come, even though the project has ended—Herschel has more than lived up to expectations.
It was with sincere emotion that scientists from not only France and Europe, but also Canada and the United States, said their goodbyes to this floating telescope while it spends a few weeks more in our solar system’s L2 Lagrange point before it enters a “graveyard orbit” around the sun.
This mission has been an example of a collaborative European space project, as it involved 15 European countries for its construction and operation, as well as scientists from the United States and Canada. France was represented within this project by the CEA, the CNRS, the Institut d’Astrophysique de Paris, and representatives of a number of universities and industrial manufacturers, such as Thalès Alenia and EADS Astrium. Herschel is considered one of the four cornerstones of European space policy, along with the Planck satellite, the Rosetta space probe meant to land on a comet, and the Gaia mission that will be launched in October in order to develop a 3D map of space.

The entire archive is accessible on the European Space Agency website:
Contact :
Olivier La Marle – Astrophysics program coordinator at the CNES - olivier.lamarle@cnes.fr

Posted on May 3rd, 2013

Last modified on 21/07/2016

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