Euclid's vision restored
March 28th, 2024
The percentage of light collected by Euclid’s VIS instrument during the heating of a mirror. After about 90 minutes, the ice reached its sublimation temperature, at which ice can transform directly into water vapor. Ice was quickly released above this temperature; the ice layer was essentially removed after another 19 minutes, when the mirror reached a temperature of –117 °C.

A new procedure was devised to de-ice Euclid's optics, which had decreased throughout in the visible due to the ice accumulated on the mirrors. These formed because spacecraft components absorbed water during assembly on Earth, and released them gradually in space. The de-ice procedure has performed significantly better than hoped, restoring Euclid's high spatial resolution in the visible.

The successful de-ice procedure has enabled scientists and engineers to tell where precisely the ice had formed, and where it is likely to form again. It will be straightforward to repeat this targeted procedure every six to twelve months, maintaining Euclid's sharp vision into the dark Universe.

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