Press Release

Herschel’s High-Tech Cooling System is Loaded with Helium for the Telescope’s upcoming Ariane 5 Launch

By SpaceRef Editor
April 22, 2009
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The Herschel space telescope for Arianespace’s next Ariane 5 mission literally “chilled out” this week with the loading of liquid helium that will help it gather data on the formation of stars and galaxies.

A total of 2,300 liters of liquid helium will be carried inside a cryostat, keeping the temperature of Herschel’s scientific instrument detectors close to absolute zero (–273ºC). This will enable the space telescope to provide an unprecedented view of the “cold universe” with observations made in far-infrared and sub-millimeter wavelengths.

The cryostat – which could be described as a “high-tech thermos bottle” – contains the space telescope’s focal plane, where infrared light will be focused from Herschel’s primary and secondary mirrors.

Liquid helium loading for the cryostat is being performed in the S5B hall of the Spaceport’s S5 payload preparation facility. Work stands were installed around Herschel, allowing the multiple supply bottles to be positioned at the right height for their helium transfer to the space telescope’s cryostat.


Herschel is 7.5 meters tall and 4.5 meters in diameter, and carries the largest telescope mirror ever to be launched into space. Built for the European Space Agency by a Thales Alenia Space-led industrial team, Herschel will have a liftoff mass of 3,400 kg.

Accompanying Herschel on the upcoming Ariane 5 mission will be Planck, a 1,900-kg. space observatory that will observe the Big Bang’s relic radiation for a better understanding of the universe’s origin. Planck also was developed in the framework of a European Space Agency program, and was produced by a Thales Alenia Space-directed industry team.

A launch date announcement for the Herschel/Planck flight is pending while additional checks are performed on the Ariane 5. This was decided after an anomaly was discovered during tests on a subassembly identical to one equipped on Ariane 5 – which has been assembled at the Spaceport, and is awaiting the integration of its dual space science payload.

SpaceRef staff editor.