ESA’s Gaia Damaged By Micrometeoroid And Massive Solar Storm – How Engineers Managed To Fix It?
24th Jul 2024
This spring, ESA’s Gaia space observatory, which operated in space for over ten years, was significantly damaged: hit by a micrometeoroid, caught in a solar storm, and some of the equipment broke down. However, engineers managed to save the spacecraft from total failure, even from a distance of 1.5 million kilometres.
Gaia – A Unique Space Observatory Exploring The Milky Way
Since December 2013, ESA’s Gaia observatory has been creating an extraordinarily precise three-dimensional map of more than a thousand million stars throughout our Milky Way galaxy and beyond. The spacecraft measures their positions, distances, mapping their motions, luminosity, temperature and composition, which gives valuable information about the origin and evolution of the Milky Way.

It’s Dangerous Out There, Even For An Astrometry Spacecraft
Gaia is located 1.5 million kilometres from Earth at the second Sun-Earth Lagrange point (L2), far from our planet’s protective atmosphere and magnetosphere. As a result, Gaia is often struck by small space particles. Of course, the spacecraft was designed to withstand such impacts.
However, in April 2024, a tiny particle (smaller than a grain of sand) – a micrometeoroid – struck Gaia at high speed and damaged its protective cover. Very high speed and the wrong angle created a little gap that allowed stray sunlight to occasionally disrupt Gaia’s very sensitive sensors and interfere with its ability to simultaneously collect light from so many stars.
A bit later, in May, engineers faced another problem – the electronics of one of the charge-coupled devices (CCDs) failed. The spacecraft’s ‘billion-pixel camera’ relies on a series of 106 CCDs – sensors that convert light into electrical signals. The sensor that was damaged is responsible for the ability to confirm the detection of stars. Its failure caused a high rate of false detections.
In addition, around the time of the sensor’s failure, Gaia was hit by the biggest solar storm in over 20 years. The spacecraft was definitely built to withstand radiation, but according to ESA scientists, it is possible that “the storm was the final straw for this piece of the spacecraft’s ageing hardware.”
Initially, Gaia was designed for a six-year mission, but it has outlived those expectations. In 2023, engineers estimated that “Gaia will exhaust its cold gas propellant (fundamental to carry out its precision pointing) in the second quarter of 2025 and will therefore transition to post-operations from mid-2025 onwards”.
The Impossible Is Possible – Gaia Returned To Its Operations
Experts from various organisations – ESOC (European Space Operations Centre), ESTEC (European Space Technology and Research Centre), and ESAC (European Space Astronomy Centre) – collaborated with specialists from the spacecraft’s manufacturer, Airbus Defence and Space, to address these challenges. Numerous experts appeared to perform the impossible to return the mission back on track.
Edmund Serpell, Gaia spacecraft operations engineer at ESOC, explained: “We cannot physically repair the spacecraft from 1.5 million km away. However, by carefully modifying the threshold at which Gaia’s software identifies a faint point of light as a star, we have been able to dramatically reduce the number of false detections generated by both the straylight and CCD issues.”
Moreover, engineers refocused Gaia’s optics “for the final time”. So, due to the concerted efforts of scientists and engineers, its mission continues, collecting data about millions of stars within the Milky Way and beyond.
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