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The Planck spacecraft, which will enable to better understand the origin and evolution of large structures in our Universe, has reached the incredible temperature of 0.1K (273.05°C) as part of final thermal-cryogenic testing at the Liege Space Center.

This new record comes within a hair's breadth of absolute zero (-273.15°C) - the equivalent of the amount of energy exchanged between two people 400 kilometers from each other.

The long testing sequence was started over a month ago to gradually lower the temperature of different parts of the payload. For the last two weeks, the entire telescope and optical cavity have been stabilized at less than 50K. The three active cooling subsystems (Sorption Cooler, 4K Cooler and Dilution Cooler) were then activated in succession to reach levels of 20K, 4K and finally the extreme of 0.1K at the coldest part of the focal plane.

Once in orbit, Planck will be the coldest point in the Universe throughout its operating life of one and a half years - even colder than Herschel, whose coldest point will be a "hot" 0.3K.

The Planck mission is a major scientific challenge, and the design and construction of this satellite is an impressive technological achievement. Testing it under these extreme conditions is an equally daunting challenge, but one that we are now meeting with the help of our colleagues at the Liege Space Center.

About Planck
The European Space Agency (ESA) had awarded a Thales Alenia Space-led consortium for the construction of two scientific satellites, Herschel and Planck.

These two satellites will be carrying very high-tech scientific payloads for cutting-edge missions:

• The Planck spacecraft will enable to better understand the origin and evolution of large structures in our Universe, immediately following the famous Big Bang. It will measure the fluctuations in the temperature of cosmological background with unprecedented resolution and sensitivity. This satellite has a design life of 1.5 years.
   
• Herschel is the follow-on to the Infrared Space Observatory (ISO), launched in 1995, for which Thales Alenia Space was also prime contractor. For the first time, Herschel will enable astronomers to study the formation and evolution of galaxies and stars since the creation of the Universe, in the submillimetric waveband. This will be the largest spaceborne telescope ever, with a primary mirror measuring 3.5 meters in diameter. The design life of this satellite is 3.5 years.

Herschel and Planck will be launched together. However, they will be separated shortly after the launch so that each one can be operated independently. They will be injected into separate orbits around a virtual point called the "second Lagrangian point", at an average distance of 1.5 million kilometers from the Earth.