>It was always expected that water could gradually build up and contaminate Euclid’s vision, as it is very difficult to build and launch a spacecraft from Earth without some of the water in our planet’s atmosphere creeping into it.<p>If they expect moisture, perhaps final assembly could be done in the Atacama?
Satellites are assembled in clean rooms, which have about 50% relative humidity to avoid electrostatic discharge. The multilayer thermal insulation or MLI recaptures 1% of its own weight after bake-out, within 24 hours in a normal atmosphere. In the vacuum of space at cryogenic temperatures, it can take years and decades for the MLI to dry up. It's a problem for all satellites, but Euclid is particularly sensitive. The Falcon9 fairing was purged with gaseous nitrogen for 4 hours prior to Euclid's launch, to at least minimize the water that could freeze out directly from the atmosphere traveling into space with the satellite.
Sometimes I'm upset that we don't have flying cars or warp drives yet, but then I think of the sheer engineering challenges in something as mundane seeming as this and can be proud again of humanity. I don't know how they ever manage to get these kinds of projects right. The JWST was a pretty crazy feat as well.
The primary source is this ESA story and it's much better:<p><a href="https://www.esa.int/Science_Exploration/Space_Science/Euclid/Operations_begin_to_de-ice_Euclid_s_vision" rel="nofollow">https://www.esa.int/Science_Exploration/Space_Science/Euclid...</a><p>The current OP is just a summary of this one.
500 Internal Server Error, so <a href="https://archive.is/20240319115956/https://europeanspaceflight.com/esa-euclid-telescope-has-an-ice-problem/" rel="nofollow">https://archive.is/20240319115956/https://europeanspacefligh...</a>