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posted by janrinok on Friday January 31 2020, @06:35PM   Printer-friendly
from the step-aside-please-coming-through dept.

Arthur T Knackerbracket has found the following story:

LeoLabs estimated that the satellites could pass within 15-30m of one another. Neither satellite could be controlled or moved. All we could do was watch whatever unfolded above us.

Collisions in space can be disastrous and can send high-speed debris in all directions. This endangers other satellites, future launches, and especially crewed space missions.

As a point of reference, NASA often moves the International Space Station when the risk of collision is just one in 100,000. Last year the European Space Agency moved one of its satellites when the likelihood of collision with a SpaceX satellite was estimated at one in 50,000. However, this increased to one in 1,000 when the US Air Force, which maintains perhaps the most comprehensive catalog of satellites, provided more detailed information.

Following LeoLabs' warning, other organizations such as the Aerospace Corporation began to provide similarly worrying predictions. In contrast, calculations based on publicly available data were far more optimistic. Neither the US Air Force nor NASA issued any warning.

This was notable, as the United States had a role in the launch of both satellites involved in the near-miss. The first is the Infrared Astronomical Satellite (IRAS), a large space telescope weighing around a tonne and launched in 1983. It successfully completed its mission later that year and has floated dormant ever since.

The second satellite has a slightly more intriguing story. Known as GGSE-4, it is a formerly secret government satellite launched in 1967. It was part of a much larger project to capture radar emissions from the Soviet Union. This particular satellite also contained an experiment to explore ways to stabilize satellites using gravity.

Weighing in at 83kg, it is much smaller than IRAS, but it has a very unusual and unfortunate shape. It has an 18m protruding arm with a weight on the end, thus making it a much larger target.

Almost 24 hours later, LeoLabs tweeted again. It downgraded the chance of a collision to one in 1,000, and revised the predicted passing distance between the satellites to 13-87m. Although still closer than usual, this was a decidedly smaller risk. But less than 15 hours after that, the company tweeted yet again, raising the probability of collision back to one in 100, and then to a very alarming one in 20 after learning about the shape of GGSE-4.

The good news is that the two satellites appear to have missed one another. Although there were a handful of eyewitness accounts of the IRAS satellite appearing to pass unharmed through the predicted point of impact, it can still take a few hours for scientists to confirm that a collision did not take place. LeoLabs has since confirmed it has not detected any new space debris.

-- submitted from IRC


Original Submission #1Original Submission #2

 
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  • (Score: 2) by deimtee on Saturday February 01 2020, @04:11AM (3 children)

    by deimtee (3272) on Saturday February 01 2020, @04:11AM (#952176) Journal

    I think the theory is you ablate it all the way to a gas. At that small and hot the particles are likely to be charged too, which means they'll interact with the magnetic field. Stuff that small will either hit the atmosphere or blow away into deep space, it won't be in stable orbits for long. Even pressure from sunlight is going to move it.
    Detractors say that you will also cause spalling, and those chips will be dangerous.

    The Saturn 5 stage 1 masses about 2500 tonnes and has enough thrust to just lift 3500 tonnes. I think we should build some more, strap a 1000 tonne tank of argon gas on top, loft it straight up (no orbital motion) to about 1000km and let the gas out. It will expand into a huge low pressure cloud and fall slowly back to earth. Anything that passes through it will be slowed slightly and drop into a lower orbit. Big stuff won't move much, and you would time it to avoid delicate stuff, but all the little shit will lose some speed, and drop into a lower orbit to burn up much sooner.

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  • (Score: 2) by JoeMerchant on Saturday February 01 2020, @04:28AM (2 children)

    by JoeMerchant (3937) on Saturday February 01 2020, @04:28AM (#952189)

    Detractors say that you will also cause spalling, and those chips will be dangerous.

    I'm with the detractors on this one, no matter how energetic the beam is those high energy pulses are going to make some larger things break up and fly off. My first thought was a lot more comforting: warm it up and let it re-radiate the energy off the surface - much less explodey stuff that way.

    Building a new Saturn 5 would be like building a new Bugatti Royale - sure, we can do it, but it will be fabulously expensive and at the end of the project you'll have a brand new horribly outdated thing. Still a BFR or whatever is in the current heavy lift production pipe should be good. Straight up is easy to explain, but I'm sure there are all kinds of rocket scientists just itching to prove how clever they are and how much more efficient a particular trajectory of release would be at aerobrake de-orbiting the most junk for the least money.

    I still like the idea of a video game kind of solution with low cost orbital robots that go forth, match orbits with junk, latch on and do kamakazi deorbit burns - it speaks to the control freak in me.

    The first satellite I ever spotted by chance turned out to be a tumbling mid-stage of a big Russian thing from the 60's - there are so many things like that up there.

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    • (Score: 2) by deimtee on Saturday February 01 2020, @04:55AM (1 child)

      by deimtee (3272) on Saturday February 01 2020, @04:55AM (#952207) Journal

      Building a new Saturn 5 would be like building a new Bugatti Royale - sure, we can do it, but it will be fabulously expensive and at the end of the project you'll have a brand new horribly outdated thing.

      Not the whole thing, just stage 1, but yeah. You could still do it with whatever the current rockets are. Calculating the best bang for the buck is not something I'm going to bother with unless Elon puts me in charge of it. :)

      I still like the idea of a video game kind of solution with low cost orbital robots that go forth, match orbits with junk, latch on and do kamakazi deorbit burns - it speaks to the control freak in me.

      The problem with this is it's great for de-orbiting the big stuff, but the big stuff isn't the problem. It's tracked and there aren't really that many of them. It's all the little stuff - a 10mm nut travelling at 14 km/s is going to ruin your day just as much as a 100kg satellite.

      The earliest satellite I remember seeing was in the 70's. It was bright enough to see in daylight, and took about 10 minutes to go from straight up to beyond the horizon. Don't know what it was, might have been skylab.

      --
      If you cough while drinking cheap red wine it really cleans out your sinuses.
      • (Score: 2) by JoeMerchant on Saturday February 01 2020, @05:17PM

        by JoeMerchant (3937) on Saturday February 01 2020, @05:17PM (#952399)

        The earliest satellite I remember seeing was in the 70's. It was bright enough to see in daylight, and took about 10 minutes to go from straight up to beyond the horizon. Don't know what it was, might have been skylab.

        My wife is sort of into Spot The Station [nasa.gov] - it usually works for us as advertised, unless there's too much cloud cover.

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