ESA’s Herschel space observatory is expected to exhaust its supply of liquid helium coolant in the coming weeks after spending more than three exciting years studying the cool Universe. Herschel was launched on 14 May 2009 and, with a main mirror 3.5 metres across, it is the largest, most powerful infrared telescope ever flown in space. Herschel carries three science instruments: a high-resolution spectrometer, HIFI (Heterodyne Instrument for the Far Infrared), and the two cameras and imaging spectrometers, SPIRE (Spectral and Photometric Imaging REceiver) and PACS (Photodetector Array Camera and Spectrometer). MPE has led the development and operation of PACS.
As a pioneering mission, Herschel is the first to cover the entire wavelength range from the far-infrared to submillimetre, making it possible to study previously invisible cool regions of gas and dust in the cosmos, and providing new insights into the origin and evolution of stars and galaxies. To be able to make such sensitive far-infrared observations, the detectors of the three science instruments must be cooled to a frigid ‑271°C, close to absolute zero. They sit on top of a tank filled with superfluid liquid helium, inside a giant thermos flask known as a cryostat. The superfluid helium evaporates over time, gradually emptying the tank and determining Herschel’s scientific life. At launch, the cryostat was filled to the brim with over 2300 litres of liquid helium, weighing 335 kg, for 3.5 years of operations in space.
Indeed, Herschel has made extraordinary discoveries across a wide range of topics, from starburst galaxies in the distant Universe to newly forming planetary systems orbiting nearby young stars. However, all good things must come to an end, and engineers believe that almost all of the liquid helium has now gone, although it is not possible to predict the exact day the helium will finally run out. A hint comes from an alternative method to monitor the helium content continuously over the mission developed at MPE: this measurement indicates that the helium will be exhausted in the second half of March.
“Herschel and PACS have already surpassed our most optimistic expectations,” says Albrecht Poglitsch, who led the development of the PACS instrument from MPE. “Our instrument was actively observing during more time than the other two instruments combined, with a nearly flawless, fully autonomous operation in its distant orbit. And, of course, we are determined to continue observing to the last drop of liquid helium!”
Herschel will continue communicating with its ground stations for some time after the helium is exhausted, allowing a range of technical tests. Finally, in early May, it will be propelled into its long-term parking orbit around the Sun.
Notes for Editors
An announcement will follow to confirm when the liquid helium coolant has been exhausted.
Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.
MICADO, the first light camera for ESO’s Extremely Large Telescope (ELT), has entered a new phase in the project: moving on from the design phase, the MICADO consortium partners have started to manufacture the various sub-systems of the instrument. On that occasion, ESO - together with the MICADO consortium - have produced the first of a collection of explainer videos.
The Danish Society of Engineers, IDA, awards the Niels Bohr International Gold Medal to Prof. Ewine F. van Dishoeck (Max Planck Institute for Extraterrestrial Physics and Leiden University, Netherlands). The medal has been awarded since 1955 for ”outstanding work by an engineer or physicist for the peaceful utilization of atomic energy”.
The European Astronomical Society awards the 2022 Fritz Zwicky Prize for Astrophysics & Cosmology to Prof. Ewine F. van Dishoeck (Leiden University, the Netherlands and Max Planck Institute for Extraterrestrial Physics). The Fritz Zwicky Prize for Astrophysics & Cosmology honours scientists who have obtained fundamental and outstanding results…
Great honour for Frank Eisenhauer: the General Assembly of the Académie des sciences, the Paris Academy of Sciences, has elected Frank Eisenhauer, scientist in the infrared group at MPE, as a foreign member. If the corona situation permits at this time, the official admission is to take place on 14 June 2022 in a formal ceremony in Paris.
The Bavarian Minister for Science and Arts, Bernd Sibler, visited the Max Planck Institute for Extraterrestrial Physics. In addition to a discussion with the Nobel Laureate and MPE Director Reinhard Genzel, he visited the integration hall and the MICADO laboratory.
A new Partner Group has been established between the Max Planck Institute for Extraterrestrial Physics (MPE) and the Department of Astronomy at the Universidad de Concepción in Chile. The focus of the group is the “baryonic cycle in galaxies” and head of the group is Dr. Rodrigo Herrera-Camus, who was postdoc at MPE from 2015 to 2019.
From 27 June – 2 July 2021 the 70th Nobel Laureate Meetings took place in Lindau. Last year’s physics Noble Laureate Reinhard Genzel from MPE was one of the 70 Nobel Laureates who met with some 600 young scientists.
The Leopoldina announced on 17 June 2021 that Reinhard Genzel, Director at the Max Planck Institute for Extraterrestrial Physics, has been elected Vice-Chancellor of the Order Pour le mérite for Sciences and Arts. He thus takes over the class of natural sciences within the Order.