3 ms·

> In 2018, ESA performed 28 #collisionavoidance manoeuvres across its fleet.

FireBeyond 7y ago
... typically of dead satellites or debris that is unable to move itself. ESA had a weather satellite in orbit, SpaceX actively moved an active satellite _into_ the same orbit as ESA's satellite (to practice maneuvers) and then said "no, we won't move it back out the way".
- manicdee 7y ago
  No. All deorbiting objects (“satellites” or debris, whatever you want to call them) are going to pass through the orbit of the ESA satellite which is intentionally in a very low orbit. It is the ESA that actively moved into that orbit by design, intention and active navigation. SpaceX intended their satellite to lift to a higher orbit but it couldn’t make it, so it is being deorbited by atmospheric drag. All orbits at the same altitude will cross at least twice. This is not a deliberate act of interception but just part of the way orbits work.
  - FireBeyond 7y ago
    That article started that the Spacelink satellite -had- been at a much higher orbit (the "regular" for their satellites, but had been brought down "to test de-orbiting maneuvers". Do you have a source to the contrary? Also, the ESA satellite has been in that orbit for 8+ years. It wasn't "moved" into the Spacelink orbit by any means. I get that en route to or from orbit, entities will pass through other orbits.
    - manicdee 7y ago
      Deorbiting is exactly the process I was describing. SpaceX did not deliberately move their craft to interfere with Aeolus. Aeolus is deliberately placed where every deorbiting craft will interfere with it. It’s like someone setting up an office in the foyer of an apartment complex. Everyone entering or leaving the complex is going to walk through the office. They aren’t deliberately walking through the office, it’s just that your office is where everyone is walking to get to where they are going. In addition, SpaceX is testing deorbiting satellites with Hall effect thrusters that are barely powerful enough to raise orbit from higher in the atmosphere. At this altitude the thrusters would have little or no effect, so the craft is more or less an inert piece of space junk which SpaceX can possibly rotate using reaction wheels and magnetic torquers. Words have meanings, and there is a vast semantic gulf between “SpaceX refused to take action” and “SpaceX were incapable of taking action”. The author used “refused” but published the article before investigating further. Expect a better story to come from the likes of Loren Grush in a couple of days once people have had time to get a response from SpaceX and digest just what is going on here (NB: ESA budget under review in November, as per ESA’s entire tweet thread of which this social media shitstorm is only responding to the first because it mentions SpaceX) This is really just a semantic argument so I will leave it here. Reread the article but completely ignore the inflammatory clickbait title and any of the author’s own (emotive, inflammatory) words on the matter, stick to only the quotes from named sources and you should be golden.
  - safsafasf 7y ago
    " SpaceX intended their satellite to lift to a higher orbit but it couldn’t make it, so it is being deorbited by atmospheric drag." I don't understand this. If the satellite is being de-orbited, why bother pissing off the ESA to save fuel?

... typically of dead satellites or debris that is unable to move itself. ESA had a weather satellite in orbit, SpaceX actively moved an active satellite _into_ the same orbit as ESA's satellite (to practice maneuvers) and then said "no, we won't move it back out the way".

manicdee 7y ago
No. All deorbiting objects (“satellites” or debris, whatever you want to call them) are going to pass through the orbit of the ESA satellite which is intentionally in a very low orbit. It is the ESA that actively moved into that orbit by design, intention and active navigation. SpaceX intended their satellite to lift to a higher orbit but it couldn’t make it, so it is being deorbited by atmospheric drag. All orbits at the same altitude will cross at least twice. This is not a deliberate act of interception but just part of the way orbits work.
- FireBeyond 7y ago
  That article started that the Spacelink satellite -had- been at a much higher orbit (the "regular" for their satellites, but had been brought down "to test de-orbiting maneuvers". Do you have a source to the contrary? Also, the ESA satellite has been in that orbit for 8+ years. It wasn't "moved" into the Spacelink orbit by any means. I get that en route to or from orbit, entities will pass through other orbits.
  - manicdee 7y ago
    Deorbiting is exactly the process I was describing. SpaceX did not deliberately move their craft to interfere with Aeolus. Aeolus is deliberately placed where every deorbiting craft will interfere with it. It’s like someone setting up an office in the foyer of an apartment complex. Everyone entering or leaving the complex is going to walk through the office. They aren’t deliberately walking through the office, it’s just that your office is where everyone is walking to get to where they are going. In addition, SpaceX is testing deorbiting satellites with Hall effect thrusters that are barely powerful enough to raise orbit from higher in the atmosphere. At this altitude the thrusters would have little or no effect, so the craft is more or less an inert piece of space junk which SpaceX can possibly rotate using reaction wheels and magnetic torquers. Words have meanings, and there is a vast semantic gulf between “SpaceX refused to take action” and “SpaceX were incapable of taking action”. The author used “refused” but published the article before investigating further. Expect a better story to come from the likes of Loren Grush in a couple of days once people have had time to get a response from SpaceX and digest just what is going on here (NB: ESA budget under review in November, as per ESA’s entire tweet thread of which this social media shitstorm is only responding to the first because it mentions SpaceX) This is really just a semantic argument so I will leave it here. Reread the article but completely ignore the inflammatory clickbait title and any of the author’s own (emotive, inflammatory) words on the matter, stick to only the quotes from named sources and you should be golden.
- safsafasf 7y ago
  " SpaceX intended their satellite to lift to a higher orbit but it couldn’t make it, so it is being deorbited by atmospheric drag." I don't understand this. If the satellite is being de-orbited, why bother pissing off the ESA to save fuel?