5 ms·
Those dense internet satellite constellations will be in low earth orbit, which have relatively fast decay times. So even in the worst case it would only set us
by the8472 7y ago
Those dense internet satellite constellations will be in low earth orbit, which have relatively fast decay times. So even in the worst case it would only set us back by a few decades while either cleanup solutions are developed or we wait for them to decay naturally.
You can still launch through the debris field into higher orbits because the collision probability will be quite low at any given moment, it just adds up over time for things that want to stay there.
- new_realist 7y agoWhat about debris from LEO collisions moving into higher orbits?
- CPLX 7y agoGravity is directional.
- Scaevolus 7y agoA single impact can't put something into a higher circular orbit-- it can create an elliptical orbit with a higher apogee (max distance), but the correspondingly nearer perigee (closest approach) means that it experiences more atmospheric drag and falls out of orbit faster.
- kupiakos 7y agoGranted, I don't know the math and this is intuition from Kerbal Space Program, but I'm not sure that's right. Wouldn't two objects colliding at 0° and 90° orbits result in a higher apoapsis and the same periapsis? Wouldn't it be equivalent to a normal impulse? Some pieces of one of the satellites would have more energy than they did before the impact.
- MPSimmons 7y agoYou are correct. The result would be an elliptical orbit, though, not the circular orbit that the post you replied to mentioned. I don't know if the person edited it after you replied, though.
- textfoo 7y agoKerbal Space Program taught me so much, I now realize. I was able to follow and visualize everything in this thread due to that videogame. Neat.
- saagarjha 7y agoI don't think the perigee needs to be lower? Consider a collision fragment that breaks off tangentially to the orbital path and moves faster than the speed needed to maintain a circular orbit: its new perigee should be the radius of the circular orbit, but the apogee will be higher.
- Robotbeat 7y agoI thought so too, but apparently this is not universally true. Some of the debris can be put in an orbit with a longer lifetime than the original satellite. I got into a long twitter argument with experts in this field, and I was proven false: some of the debris can have longer orbital lifetime and go to higher orbit. EDIT: Here: https://twitter.com/SpaceJosh/status/1119721780254371840 https://twitter.com/SpaceJosh/status/1119721780254371840 Always embarrassing to make a fool of myself on the Internet, but losing an argument IS a very effective way of learning.
- avar 7y agoYou said: > That seems unlikely, as that requires like 11km/s which is more than the sum of the two velocities[...] Isn't the first problem here that you're assuming a spherical cow in a vacuum physics problem? Two satellites colliding aren't two indivisible pebbles colliding. They're going to pulverize on impact, and some of the now-expanding debris cloud might even contain combustibles the satellites were carrying. The debris also won't only collide once, there'll be a series of rapidly occurring re-collisions. Some of those might impart extra velocity on some of the expanding debris.
- choonway 7y agoGalilean cannon?
- deleted 7y ago[deleted]
- caymanjim 7y agoHigher orbits require higher velocities, which aren't going to be reached by collision debris.
- jcims 7y agoIt’s not likely but definitely not impossible. https://youtu.be/2UHS883_P60 https://youtu.be/2UHS883_P60
- jcims 7y agoFor the sake of completeness, did a little digging, looks like it did happen in fact - https://celestrak.com/events/collision/ https://celestrak.com/events/collision/
- jessriedel 7y agoCollisions can absolutely eject debris at a higher velocity than either of the initial impactors.
- deleted 7y ago[deleted]
- JohnJamesRambo 7y ago>only set us back by a few decades Uhhh, that’s quite some time.
- LeifCarrotson 7y agoIt is interesting to think about. Assume for a minute that Starlink and Amazon's project and a handful of others put tens of thousands of satellites into 500-600 km LEO. Two crash, bits of those crash into others, and runaway Kessler syndrome ensues, resulting in space at those altitudes effectively closed off for 25 years. Assume the ISS at 400 km is no longer safe for human habitation, and it's too risky to try to punch larger payloads through to higher orbits. Human space exploration is effectively dead for 25 years. What happens? On the scale of human history, that's a moment in time. Today, as we learn about the history of colonial Europe, there's lots of exploration, then the 30 Years War in 1618 slowed that down a lot for a while, then things resumed. In 2500 AD, astronauts will learn of the early history of 1900s first flights, and the 2020-2045 setback, and then 400 years of further development. But in the short term, that's a full career for everyone who just entered the field. Space companies would publish 100 quarterly earnings statements with zero progress, just waiting for the window to open again. I just don't know that modern society has the ability to think long-term for an event like that.
- Gumboot 7y agoFYI it appears that for a unpowered satellite at 500-600km the average lifetime is around 5 years. https://space.stackexchange.com/questions/13851/how-long-can-a-leo-satellite-maintain-its-orbit-if-it-loses-all-power https://space.stackexchange.com/questions/13851/how-long-can...