The European Space Agency (ESA) is working hard to find a solution to a problem that could ruin observations of the universe made by the Euclid telescope in space. A layer of water ice, thinner than a DNA strand, is affecting its vision.
The issue is common for spacecraft operating in orbit outside the planet in the stark coldness of space. The problem, however, if not solved, could lead to major observational issues as the telescope investigates the nature of the dark Universe.
The Euclid team is now testing a newly designed procedure to de-ice the mission’s optics that could keep the telescope’s optical system as ice-free as possible for the rest of its life in orbit.
Launched on July 1, 2023, the Euclid telescope successfully reached its destination orbit, the Sun-Earth Lagrange point L2, a month later.
However, as calibrations began, experts noticed a small but progressive decrease in the amount of light measured from stars observed repeatedly with the visible instrument (VIS).
The space agency said that the ice layer is the result of water being released from the components that freeze in space. This water was absorbed from the air during the assembly of the telescope on Earth.
In the cold of Euclid’s new home, those released water molecules tend to stick to the first surface they land on – and when they land on this highly sensitive mission’s optics, they can cause trouble.
“We compared the starlight coming in through the VIS instrument with the recorded brightness of the same stars at earlier times, seen by both Euclid and ESA’s Gaia mission. Some stars in the Universe vary in their luminosity, but the majority are stable for many millions of years. So, when our instruments detected a faint, gradual decline in photons coming in, we knew it wasn’t them – it was us,” Mischa Schirmer, calibration scientist for Euclid said.
Following its launch, the Euclid telescope underwent an ‘outgassing campaign’ to eliminate water molecules on or near its surfaces.
Despite efforts, some water remained absorbed in the insulation layers, slowly releasing into space. Research revealed microscopic layers of ice on Euclid’s mirrors, affecting its light reflection.
To address this, a plan was devised to heat the spacecraft gradually, starting with low-risk optical parts. If successful, further heating will be applied to additional mirror groups. This procedure aims to restore Euclid’s light-collection ability without disrupting its mission timeline. With ongoing water release, a long-term solution is crucial.
While de-icing is expected to safeguard Euclid’s performance, it’s a new process, requiring careful implementation to ensure mission success.
Identifying the affected surfaces accurately is imperative, emphasising the significance of this unprecedented operation in space exploration.
Shambhu Kumar is a science communicator, making complex scientific topics accessible to all. His articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
