author: Camiile Gévaudan
translation: GoogleTranslate/doxa-louise
The European Space Agency had to do a bypass to prevent one of its satellites from hitting the SpaceX company. As the number of spacecraft in low orbit is growing very quickly, it is becoming necessary to automate risk management.
Satellite collision avoided: ESA calls for space code of the road
It did not go far ... Monday morning, a weather satellite of the European Space Agency (ESA) had to make an avoidance maneuver not to hit a small satellite SpaceX, the US private company that breaks the costs space with its reusable rockets. This type of emergency is still rare, but at the rate at which SpaceX is deployinh Earth's orbit, it could become more and more common. How did we get here ?
ADM-Aeolus is a European ground-based atmospheric observation satellite, launched in August 2018 and expected to last three years. Starlink 44 is a small soldier among the army of sixty SpaceX satellites launched in May 2019. They aim to create an extensive telecommunications network capable of providing broadband internet worldwide. These sixty "satcoms" are only the precursors: the Starlink network should soon have 1600 satellites, then 4 400, and eventually 12 000 in the mid-2020s. This is called a "mega-constellation" "... and the project is very controversial. There are currently "only" 5,000 satellites in Earth orbit. SpaceX would triple that number alone, with all the congestion and pollution issues involved.
And we are already seeing problems. Starlink 44 was caught spinning straight toward Aeolus. The US military, which monitors the trajectory of satellites, alerted ESA and SpaceX: the risk of collision was one in a thousand - far above the warning threshold set by the ESA to launch a avoidance maneuver. SpaceX received the message but did nothing to deflect its satellite, says Holger Krag, who heads ESA's Space Debris Office: "We informed SpaceX, who responded and said that they did not intend to react. At least now we knew who was going to have to. "
The European Space Agency then triggered its avoidance maneuver, apparently annoyed at having to take this responsibility, as it claimed on Twitter and announced on its website : "For the very first time, the ESA had to make a disruptive collision avoidance maneuver to protect one of its satellites from collision with a mega-constellation. Aeolus turned on its engines and diverted its path to avoid a SpaceX satellite from the Starlink constellation. " Was it really worth complaining publicly? Matt Desch, head of Iridium, a constellation of 75 satellites, opined :"Hmm. We move our satellites once a week on average and we do not release a press release to comment on all our maneuvers. "
View of the European Aeolus satellite observing a cyclone.View of the European Aeolus satellite observing a cyclone. (Image ESA / ATG medialab)
The European agency was perhaps upset at having to take care of the avoidance - which consumes precious fuel and can shorten the life of the satellite - while its Aeolus is well installed in a orbit of 320 kilometers, which he has been occupying for a year. Starlink 44 did not land until May in this neighborhood: instead of staying at a prudent 550 kilometers like other Starlink objects, it descended lower (between 311 and 345 km) on the initiative of SpaceX to test its propulsion systems and the processes of deorbitation. If there is a risk of collision, who should give way? First come first? Priority rights ? "There are no rules in space ," says Holger Krag at Forbes .No one has done anything wrong and space is open to everyone. In each orbit we might encounter other objects. " Most often, it is about satellite debris, which constitute 90% of the objects tracked in orbit. ESA has conducted twenty-eight debris avoidance maneuvers in 2018. But none to circumvent functional satellites, rarely seen.
With mega-constellation projects like Starlink or Oneweb , low orbit will fosterer traffic jams and the risk of accidents will increase. "Avoidance" manual "collisions as is done will become impossible today" , fears the ESA , which relies on artificial intelligence to automate the process.
As the number of satellites in orbit increases, due to 'mega constellations' such as #Starlink comprising hundreds or even thousands of satellites, today's 'manual' collision avoidance process will become impossible...
For its part, the SpaceX company defends itself by claiming that it did not receive the correct warning message because of a bug: "Our team exchanged with the Aeolus team on August 28, when the probability of collision was only one chance out of 50,000, far from the alert threshold , she explains to Forbes .At that time, both ESA and SpaceX felt that a maneuver was not necessary. Then the US Air Force updated its estimate to more than one in 10,000, but a bug in our surveillance system prevented the Starlink operator from seeing further correspondence on this rise in probability. SpaceX is investigating the matter and will take the necessary steps to correct the problem. If the Starlink operator had seen the message, we would have coordinated with ESA to determine the best approach, a maneuver on their side or ours. "
The bottom line is that everything turned out well. The ESA maneuver was carried out a half-orbit before the potential collision, and Aeolus then contacted Earth as usual to send in its scientific data, signaling that it was working like a charm. Krag and his team say they trust SpaceX will be more vigilant in the future, and will put strict rules in place as the Starlink constellation expands: "What I want is for space traffic to be organized. In such situations, one must know who has to react. And of course automate the system. When we have 10,000 satellites in space, we will not be able to continue working with operators who write e-mails to decide what to do. That's not how I imagine modern astronautics. "
https://www.liberation.fr/sciences/2019/09/04/collision-de-satellites-evitee-l-esa-reclame-un-code-de-la-route-spatial_1749211
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