e European Space Agency (ESA) launched the Sentinel-1A satellite in 2014 as part of its Copernicus Program, the largest earth observation project in history. The satellite was deployed without incident and has been making radar scans of Earth ever since. However, the ESA detected an unusual drop in power on August 23rd. It turns out that Sentinel-1A was hit by a teeny, tiny meteorite that made a considerably larger hole.
Sentinel-1A has two large solar panel arrays that supply it with more than enough power to keep it operational. Thus, it wasn’t an emergency when the power drop was detected. It might have been a sign of a larger impending failure, so the ground control team began investigating. There are several cameras on the satellite that were used to monitor solar panel deployment after the 2014 launch, but they were never intended to be used again. The ESA was able to fire them up and beam the images back to Earth, though.
The camera feed showed a section of the solar panel had been damaged, most likely from a collision with a micro-meteorite. The damaged area is about 40cm across (about 15.7-inches). The loss of power won’t be a problem for the satellite, but it’s a reminder of how fast things are moving in space. Even something tiny can have a huge amount of energy if its relative velocity is a few kilometers per second.
Ground tracking stations are supposed to warn of possible impacts so a satellite can move out of the way, but we can only reliably spot objects 5cm or larger in diameter. The ESA estimates that the object that struck the solar panel was no more than a few millimeters across — a space pebble. Had it been much larger, it could have caused serious damage to the craft. The ESA expects Sentinel-1A to continue operating normally.