The Gaia spacecraft of the European Space Agency (ESA) is back in operation after experiencing a rare double impact from a meteorite and a solar storm.
The Gaia spacecraft orbits Earth at an altitude of approximately 1.5 million kilometers at the Lagrange Point L2, where the gravitational forces of Earth and the Sun create a stable orbit. The mission’s goal is to create a 3D map of every star in the Milky Way galaxy.
Simulation of the Gaia spacecraft of the European Space Agency (ESA) mapping the Milky Way galaxy. (Image: ESA/ATG medialab/ESO/S. Brunier).
In April, a meteorite smaller than a grain of sand struck Gaia, damaging the protective shield surrounding the spacecraft’s equipment. Subsequently, sunlight entering through this small crack interfered with the operation of the sensors. By May, a malfunction occurred in a part of the system that helps Gaia validate newly discovered stars, leading to thousands of incorrect detections. According to ESA, this second malfunction may have originated from a solar storm that caused auroras to spread across the world’s skies in May.
“Gaia typically transmits over 25 gigabytes of data to Earth each day, but the data would be significantly bulkier if the onboard software did not filter out erroneous star detections first. Both recent incidents disrupted this process. As a result, the spacecraft began generating a large volume of incorrect detections, overwhelming our systems,” said Edmund Serpell, operations engineer for the Gaia spacecraft at the European Space Operations Centre, on July 17.
Although the Gaia team could do little with the hardware, they fixed the software to keep the spacecraft operational. Specifically, they adjusted the threshold at which Gaia classifies an object as a star.
Launched into space in 2013, Gaia was initially designed to operate for six years but has now been in service for over a decade. The spacecraft is expected to continue collecting data until the end of 2025 when its propulsion system will deplete its fuel.
Gaia has previously assisted astronomers in discovering some of the oldest stars in the Milky Way, formed over 12.5 billion years ago. The spacecraft has also identified faint “companions” of large stars and a binary star system, where the disk of one star obscures the other. Data from Gaia has even helped scientists estimate when the Milky Way will collide and merge with the neighboring Andromeda Galaxy—approximately 4.5 billion years from now.
