Space

ESA fires satellite thrusters to avoid collision with SpaceX Starlink probe

ESA fires satellite thrusters ...
Artist's impression of the Aeolus satellite in orbit
Artist's impression of the Aeolus satellite in orbit
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Artist's impression of the Aeolus satellite in orbit
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Artist's impression of the Aeolus satellite in orbit
60 Starlink satellites stacked inside the SpaceX Falcon 9 rocket's fairing segment prior to the May 2019 launch
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Sixty Starlink satellites stacked inside the SpaceX Falcon 9 rocket's fairing segment prior to the May 2019 launch

ESA has been forced to reposition an Earth-observing satellite to avoid a potential collision with a member of SpaceX’s Starlink mega constellation. The avoidance maneuver took place just half an orbit before the orbital clash could occur.

The low-Earth orbit environment is becoming ever more crowded, increasing the risk of satellite-on-satellite collisions. Space agencies around the world are constantly tracking both active and defunct satellites, along with over 22,000 of pieces of space debris in the hope of avoiding such an event.

However, a growing number of companies are intent on placing their own mega constellations in orbit – vast shoals of hundreds or even thousands of satellites.

On May 23, 2019, SpaceX launched 60 communications satellites – all of which belonged to the company’s Starlink mega constellation – aboard a single Falcon 9 rocket. The constellation, which has the goal of providing worldwide broadband internet access, could eventually be comprised of almost 12,000 satellites.

Should one of the 227-kg (500-lb) satellites collide with another human-made object, it would create a swarm of hazardous debris that could go on to take out other satellites, creating a knock-on scenario. In its worst form, this is known as the Kessler effect, and at the very least it would make the space environment a more hazardous place.

60 Starlink satellites stacked inside the SpaceX Falcon 9 rocket's fairing segment prior to the May 2019 launch
60 Starlink satellites stacked inside the SpaceX Falcon 9 rocket's fairing segment prior to the May 2019 launch

Today, ESA announced that it has fired the thrusters of its Earth-observing Aeolus satellite in order to remove itself from a potential collision with a Starlink satellite. The maneuver occurred half an orbit before the would-be collision could take place. The maneuver, which was planned and executed by ESA’s Space Debris Office, took a significant amount of time to prepare.

In a string of tweets following the event, ESA emphasized that the proliferation of space debris and active satellites would require a shift from human managed avoidance maneuvers to automated, artificial intelligence guided maneuvers.

Following the repositioning, Aeolus was able to make contact as usual and transmit science data.

According to ESA this is the first time that it has ever had to reposition one of its satellites to avoid an object belonging to a mega constellation. However, the agency has had to alter the trajectory of its LEO orbiters many times in the past to avoid other potential hazards.

Last year alone ESA performed 28 collision avoidance maneuvers, largely in an effort to keep its probes safe from defunct satellites or debris. It is extremely rare for the threat to be posed by an intact satellite, let alone an operational one. Sadly, however, these events are likely to become much more common as access to space becomes cheaper.

Source: ESA

1 comment
Brian Smith
I wonder when both satellites are active and both could expend some of there precious propellant how is it decided who moves and who get to stay on there existing coarse? Is there a system in place to dictate the rules of who has to use some propellant or is it a game of chicken to see who moves first?