The European Space Agency’s Swarm mission is made up of three spacecraft circling Earth to study our planet’s magnetic field. Recently, the constellation was renamed. Do an emergency maneuverSpace debris collisions can be avoided by avoiding them as quickly as possible.
This move isn’t unusual. ESA stipulates that satellites must make collision avoidance maneuvers at least twice a year. This dodge was performed without much notice and Swarm was already climbing towards safety from another threat.
A piece of the was found after the alert. space trashIt was too close to home for comfort. Two of the three satellites were moving to higher altitudes to avoid sunburn.
The sun has been moving towards the Active part of the eleven-year cycle when more and more powerful solar flares can bombard Earth’s upper atmosphere. This can increase the density of the orbiting satellites, slowing down their progress, burning more fuel, and potentially dragging them back to Earth’s surface. Thus, the satellites were in the middle of a 10-week-long process of moving into higher orbits.
This was all happening when a chunk of orbiting junk, which had been detected on June 30, threatened to collide with a spacecraft just eight hours later.
That’s a very short amount of time to plan an evasive maneuver. Such a move typically requires a lot of checking that the alteration doesn’t put it at risk of other collisions and also figuring out how to get back to the original path it’s supposed to be on when the threat has passed.
ESA designed and executed the evasive action within four hours. Swarm then returned to climbing less that a day later.
So the danger has passed, but only for now, as there’s more debris than ever far above our heads.