Planck is in Liège!
A life filled with technological problems and challengesPlanck’s presence at the CSL during the summer season will be noticed. The Center’s priority is conducting the tests on the complete satellite before it is sent into space. The CSL was expecting Planck at the end of 2007, but unexpected difficulties and delays forced it to reschedule its work with the European cosmological observatory. Another technological problem that had to be solved: the use of a panel indicating three reference sources that had to come down in front of the HFI instrument assembly and allow it to be calibrated with a heretofore unattained degree of precision. This panel is similar to a liquid helium bath, and was designed to function in a stable manner at temperatures around 4 Kelvin (– 269°C). Support for the Big Bang theoryIn order to keep the core of its payload temperature-controlled under extreme conditions, Planck uses a passive heat sink down to 50 K, and three active cooling units to maintain temperature at 20 K, 4 K, and 100 micro-Kelvin (mK). The latter value for the cooling of the focal plane of the HFI instrument group is achieved by a system of dilution of two isotopes of helium, helium 4 and helium 3. The first occurs naturally, but helium 3 is only produced as a byproduct of nuclear fission, and is one of the most expensive substances in the world (at about 1.2 million euros per kilogram). For Planck alone, the amount used represents two years worth of world production! |
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© 2007 ULi�ge
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