One cool way of de-orbiting satellites is to brake against the Earth's magnetic field with a conducting wire. This is actually already a product.
Decluttering low-Earth orbit: It's time to tidy up space
91–100 of 136 posts
Re: Decluttering low-Earth orbit: It's time to tidy up space
#92Earlier quoted context omitted.
Meanwhile USA has 25x the debris (as of June 2019). Glass houses... https://orbitaldebris.jsc.nasa.gov/quarterly-news/pdfs/odqnv... https://www.businessinsider.in/us-russia-china-and-india-sta...
I think the concern is that despite increased activity in space, most countries have slowed down the amount of dangerous debris being created. Meanwhile, India created about as much space junk in a day as the US creates in 1-2 years. That's despite claiming that the the test was in an orbit that wouldn't leave any longterm debris.
Easy to criticize other countries when you've already had your space race.
I do find it annoying that space is usually jingoistic bullshit involving flags and rousing speeches instead of actual science. I'm glad ESA never went that way.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#93Earlier quoted context omitted.
But there's an enormous difference between cosmic dust, which generally doesn't pose any threat to satellites or spacecraft, and the man-made "junk" that are essentially destructive whizzing bullets, cannonballs, and worse. The total mass is essentially irrelevant, what matters is the mass of individual objects. > Or, at least they are in orbits where danger from natural debris is vastly greater than from space junk.…
a rock the size of pebble or as small as a grain of sand will cause a very bad day when you realize that some of the objects have incredible amounts of kinetic energy due to the speeds involved (the speed of the rock or the speed of the thing to be damaged).
For many satellites the biggest cross sectional area are solar panels. So the most likely part of a satellite impacts by debris will be there.
In terms of probability with debris impacts on satellites the common effect is a slight drop in power output from the solar panels [0].
Keep in mind stuff in orbit is pummeled by micrometeoroids pretty regularly. These are literally dust size grains of material in orbit. They face pretty constant abrasion yet remain fully functional.
[0] https://www.space.com/20925-space-station-bullet-hole-photo....
Re: Decluttering low-Earth orbit: It's time to tidy up space
#94> The best idea, though, is to attack the problem at its roots. The littering of space is an example of the “tragedy of the commons”, in which no charge is made for the use of a resource that is owned collectively.
Garrett Hardin's article which created and promoted the "tragedy of the commons" doesn't describe historical "commons" at all, which were all managed over extended periods of time by complex rules and social norms. The "tragedies" happened primarily when capitalism emerged and demanded an end to the historical management of commons, allowing the interests of capital to destroy them.
Space might actually be the first really good example of "the tragedy of the commons" inasmuch as it was a new, globally accessible (i.e. not geographically determined) resource which began to be used without any establishment of the usual norms and rules that accompanied historical commons. Something similar presumably happened with the oceans, but their physical nature (i.e. stuff sinks, and stuff moves) hasn't created an issue in the same way that is now happening in orbit.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#95Is this really a thing... orbit is a vastly bigger place than the earths surface... you’d have to try pretty hard to hit that junk wouldn’t you?
Check this site out, it's a catalogue of known stuff in space http://stuffin.space/ The ISS has regular enough operations required to dodge debris detected approaching for a near miss in space that I think it's definitely a concern for future operations. Consider as well that stuff in orbit is going ~25,000km/h or more and at that speed even a small bolt would decimate a spacecraft on impact.
I always dislike those visualisations as it gives the impression it’s crowded, because the dots aren’t to scale.
Are the orbits in opposing directions? If not, then the 25k number isn’t meaningful right? Their relative velocity is what matters
That’s interesting about the ISS I hadn’t heard of that as a regular thing.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#96Earlier quoted context omitted.
I don't have a good feel for the numbers either, but surely if you make the Space Sponge big enough, things will get caught in it. There is almost certainly a better material to use as well, but I don't think either of these practical concerns invalidates the idea. Of course, big enough Space Sponges to make a practical difference would be very visible to the naked eye.
Well, the reason why I brought up Newton's impact depth formula is that it quite clearly shows you have to have enough "braking" material up there. Distributing it over a greater area reduces the effectiveness proportionally. The problem in the end is launch costs. Yes, we're getting better, but that doesn't mean we can shoot up a "visible to the naked eye"-sized impactor. Not to mention what difficulties an object o…
OK, you've convinced me.
Even if launching costs ever makes this feasible, any Space Sponge big enough to be efficient would be a big collision problem in itself.
Re: Decluttering low-Earth orbit: It's time to tidy up space
#97Earlier quoted context omitted.
"much slower" is still >7000 m/s
Yes but at that altitude their orbital period is about 1/2 that of low orbits, meaning that even if two orbits do cross paths, there would be fewer potential collisions in a given time. They are 'slower' in relation to size of the sphere they occupy.
90 mins at 400km vs 110 mins at 1400km
Re: Decluttering low-Earth orbit: It's time to tidy up space
#98Earlier quoted context omitted.
Check this site out, it's a catalogue of known stuff in space http://stuffin.space/ The ISS has regular enough operations required to dodge debris detected approaching for a near miss in space that I think it's definitely a concern for future operations. Consider as well that stuff in orbit is going ~25,000km/h or more and at that speed even a small bolt would decimate a spacecraft on impact.
I always dislike those visualisations as it gives the impression it’s crowded, because the dots aren’t to scale. Are the orbits in opposing directions? If not, then the 25k number isn’t meaningful right? Their relative velocity is what matters That’s interesting about the ISS I hadn’t heard of that as a regular thing.
Just to follow up on the ISS, they have made a total of 20 avoidance maneuverers and they do it if they calculate the chance of hitting as greater than 1 in 10000.
So it is a thing, but I wouldn’t call < 1 per year regular
Re: Decluttering low-Earth orbit: It's time to tidy up space
#99Fun fact: A hobby satellite my father helped build as a way to justify procrastinating during university in the late 60s is now low Earth orbit space junk. He says he's rather embarrassed to have learned, post launch, that it would likely remain in orbit for 100,000 years. https://en.wikipedia.org/wiki/Australis-OSCAR_5 http://centralblue.williamsfoundation.org.au/oscar-5-the-fir... https://www.youtube.com/watch?v=hj…
> Launch date: 23 January 1970
Phew, 23 days earlier your father would have had to code all timestamps in negative.
Joke apart, which OS did such satellites run? Unix? Probably not, since timestamps only started in 1970. Just "C"? Even today, how do you register time on satellites? With Unix timestamps (a long since 1970-01-01)? Can they synchronize based on objective points (stars or Earth position to the sun) or are satellites always resynchronized from Earth signals?
Re: Decluttering low-Earth orbit: It's time to tidy up space
#100Fun fact: A hobby satellite my father helped build as a way to justify procrastinating during university in the late 60s is now low Earth orbit space junk. He says he's rather embarrassed to have learned, post launch, that it would likely remain in orbit for 100,000 years. https://en.wikipedia.org/wiki/Australis-OSCAR_5 http://centralblue.williamsfoundation.org.au/oscar-5-the-fir... https://www.youtube.com/watch?v=hj…
> Launch date: 23 January 1970 Phew, 23 days earlier your father would have had to code all timestamps in negative. Joke apart, which OS did such satellites run? Unix? Probably not, since timestamps only started in 1970. Just "C"? Even today, how do you register time on satellites? With Unix timestamps (a long since 1970-01-01)? Can they synchronize based on objective points (stars or Earth position to the sun) or ar…
Back then most satellites were likely just hardwired electronics, possibly with some limited remote command support. Sure, there were exceptions for high profile missions such as space probes and spy satellites.
IIRC there have been some proposals to use Pulsar signals on satellites/probes not just for time synchronization but more importantly navigation. Not sure if it's actually in production use yet.