A meteorite and solar storm almost deprived us of the astrometric satellite Gaia

The European Space Agency reported that the astrometric satellite Gaia was hit by space disasters. Its protective shell was pierced by a micrometeoroid, and a severe solar storm in May of this year disabled the CCD sensor, which is critical for the operation of the observatory. Engineers have returned the satellite to service, although the amount of data it receives appears to have been greatly reduced.

Image source: ESA

The Gaia satellite is located at the Lagrange point L2 (in the shadow of the Earth on the side opposite the Sun). Its huge CCD field and two telescopes capture data on millions of stars every second, allowing them to monitor their speeds and directions. In fact, “Gaia” creates a three-dimensional dynamic map of our galaxy and even looks beyond its borders. The importance of this data cannot be overestimated, and in many ways it has not even been studied, such a meaningful array of information they represent.

In April, a micrometeoroid hit the satellite’s protective casing. It entered at the “wrong” angle and at a high speed that the casing could not compensate for. In the earth’s atmosphere, such a speck of dust would instantly evaporate. But for “Gaia” her blow had consequences. Scattered sunlight began to enter through the hole made by the micrometeoroidorm, which created false positives on the matrix – it began to show non-existent stars.

While engineers were solving the problem of reducing the sensitivity of the satellite’s matrix to compensate for damage, a new problem arose. In May, the CCD matrix, which worked as a control matrix to filter out false positives by stars, failed. Engineers cannot say exactly the reason for the failure, but they associate it (in time) with the strongest solar storm in many years, the effect of which in the form of auroras was visible even in the Krasnodar Territory. The satellite worked almost twice as long as its allotted 6 years, and the electronics could have worn out significantly under constant cosmic radiation.

Milestones in the 10-year operation of the Gaia satellite

Therefore, following the solution to the problem of extinguishing scattered sunlight through a hole in the protective casing, engineers lowered the sensitivity threshold of the main matrix to eliminate the appearance of false stars. Work to restore the observatory was successfully completed. Moreover, the re-calibration of the telescopes increased the accuracy of measurements to a level that the satellite had not previously achieved. Today, the observatory transmits 25 GB of data to Earth every day. There would be much more of them if the on-board equipment did not work to compensate for false alarms. But even this stream of data is an invaluable contribution to the study of the Universe.