Esa satellite must dodge Musk's Starlink satellite


Mr Krag, on Monday morning, an Esa satellite had to dodge for the first time another satellite that is part of a so-called mega-constellation – a planned network of thousands of satellites. The satellite was one of the first 62 test satellites of the “Starlink” constellation, which is currently being built by Elon Musk. What exactly happened?

Sibylle Anderl

We monitor our satellites around the clock and check every incoming collision warning. In this case, our Aeolus satellite had to dodge for the first time during its mission. Such a maneuver occurs in the entire fleet a few times a year. The normal case – more than 90 percent of cases – is that we are dealing with a piece of space junk. This time it was a powered satellite at a height where you would not expect anyone else. Aeolus flies 320 kilometers deep, there is actually very little going on.

How is it different to avoid a satellite instead of a piece of space junk?

If you have a collision warning with a space junk object, the case is clear: then the satellite has to dodge. But when you encounter another powered satellite, you have to coordinate. The way this coordination works today is – you can say – primitive, because it works via e-mail and by phone.

There are no official “right of way” rules?

No, there are no right of way. There is not even a rule that you have to dodge at all. There are no communication protocols, and it is not clear what information needs to be exchanged. There is not even a catalog of phone numbers that you can call. It necessarily requires a modernization. We currently have 2000 satellites in space. This number will increase significantly. We are now seeing more and more that in view of the increase in space traffic, we must have a solution.

Dr.-Ing. Holger Krag is head of the Esa space security program.

How did the communication with SpaceX work?

SpaceX said in this case that they are currently not planning a maneuver. And we decided to maneuver because the risk was too high for a 1: 1000 collision probability, Indeed, it is enough if one maneuvers and we have told them what we intend to do. The cases, if you do not get an answer, are the problematic, because then you are unsure until the end, if what you do is really the right thing. If both move in the same direction, the problem is not solved.

So, SpaceX has relied on the Esa to take care of the problem?

That is hard to say. Maybe we reacted too fast and they said to each other: “Ok, then we do not need to do anything anymore”. The other is: the collision risk is not calculated in a standardized way. Maybe they came to a different conclusion than we did. But that's not what worries us. The effort to negotiate in the future could be almost greater than the effort of maneuvering. After all, we have many more collision warnings than actual evasive maneuvers, and many of the warnings eventually settle for pleasure. But for every warning you have to act and deny yourself. Since the effort goes into it. If you have to negotiate manually with several operators daily, who maneuvers where, which can not be the future of space travel.

What would a solution look like?

The process of consultation must be modernized and more professional. We will now propose a program to our member states, “Space Safety”, which will be presented at the Esa Council of Ministers in November, where we also want to put solutions to this issue.

And in fact, probably the time pushes: Soon SpaceX wants to increase its satellite fleet to more than 10,000. Other companies want to follow …

I think in the next two to three years we should have technical solutions that make our job much easier. Communication protocols, automatic decisions based on machine learning. Maybe also the possibility to reach the satellite at any time and not only if it overflies a ground station, so that one can react more flexibly. Our proposal is to demonstrate by 2023 that a satellite makes a decision after an incoming collision warning, then votes and then autonomously evades. Autonomous does not mean that he does everything on board, which of course requires contact with the ground. But at the moment we are not able to do that. Many experts are paid to stay awake around the clock and assess the situation. And that's no longer manageable if we soon have five times the number of satellites.

. (dayToTranslate) Elon Musk (t) ESA (t) SpaceX (t) Space Security (t) Rule of the Road (t) Satellite (t) Space debris


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