Planck: toward the origins of the universe [ Return towards  Cryogenics: cold for space  ]

This light, called fossil radiation, still travels freely in space, but it is very hard to detect because it is extremely fine. The information obtained on the birth of the universe will make it possible to provide details on the initial physical conditions and the formation mechanisms of the galaxies.

To study fossil radiation, Planck must detect variations in temperature of the order of a millionth of a degree, in a range of temperatures close to 2.725K, the temperature of interstellar space. To do so, its measurement instruments must themselves be at a temperature below those observed.

The Planck’s cooling system is comprised of a complete cryogenic chain whose last link is the dilution cooler supplied by Air Liquide. It will enable the detectors’ temperature to be lowered to 0.1K, then be stabilized at this temperature to near a millionth of a degree. The dilution uses very high purity gases: helium 3 and helium 4. This is the first time that this technology has been qualified for use in space.

Apart from the cooler, which is at the heart of Air Liquide’s technological contribution, the Group has also supplied several pieces of equipment to fill tanks on the ground with ultra pure helium at 300 bar, as well as a monitoring unit to guarantee the cooler’s correct operation in flight.

Planck weighs about 2 tons and will carry a telescope 1.5 meters in diameter as well as two scientific instruments (HFI and LFI, High and Low Frequency). The mission’s anticipated length is about two years.