On one of Joe Rogans Podcasts, Neil Degrasse Tyson had said that there is a very good chance we will trap ourselves on Earth before we can become a true space faring civilization.
The 'trap' is that the accumulation of space junk will interfere with attempts to launch space ships and/or disrupt orbiting satellites to the extent that we can no longer see from space telescopes, hence we are trapped on Earth :-(
If the stakes are high enough, you will find people willing to risk the launches. Missions will just be unable to use very polluted orbits and there will need to be planning around that. You would need a ton of debris to make every launch site and mission type in the world useless.
I expect the trap will be political/economic rather than technical: We'll have ways to fix it, but you won't get enough groups to come together and pay for it.
I study orbital debris for a living - I'd like to assure you that you don't need to feel too worried about that. Orbital debris is generally consolidated in very thin altitude bands. Rockets on an escape trajectory spend very little time in these shells, only in passing. Compare that to satellites with lifetimes of 15 years.
Niel's statement is analog to saying "The LHC could create a black hole that kills us all". Yeah... I guess on some theoretical level it's possible... but it's extremely unlikely. Same concept applies here. I'm quite disappointed in him saying "There's a very good chance", because that is far from true.
Here is the clip from when they start speaking about the space junk. My memory did not quite remember the exact words Neil used so what I wrote was not entirely accurate. Apologies.
The first line of Seveneves is "The moon exploded with no warning and no apparent reason". The Kessler effect is involved, but its not really about space junk at all
(spoiler ahead - go read the book instead of this post)
The moon breaks in half in the first page, but a cascade event happens about a hundred pages into the book, then further changes happen :) . So I think it is accurate to say that it is analogous!
I wonder if, in the future, something like 'Planetes' would become reality. Space janitors in some sense policing space junk in orbit be it operators controlling collection robots or actual human space-walk collectors themselves.
Collisions are the problem. When to large things collide they create hundreds of little things. So any space janitors, as large things themselves, would only increase the number of collisions and thereby exacerbate the problem.
The relative speeds of any two objects in low orbit means that physically catching much of anything is horribly inefficient. The DeltaV requirements for a robot grabbing one thing, then moving to grab another, means you are probably better off launching a separate robot for each target. Any complete answer must therefore involve some means of moving debris without physically touching it. Magnets and lasers are the only hope.
They will not work on the scale of kinetic energies involved. Stuff with orbital velocities has so much energy that even metals start to behave like fluids, so an elastic net will be torn after the first impact.
This is not true because most satellites are in similar orbits, largely because it's easer going east due to earths rotation. Similarly, you could cheaply visit every satilite in geosynchronous orbit. Further, you can pick trash up in an order designed to minimize delta V, and use thing she like solar sails or ION drives.
Polar orbits are something of an exception, as are consolations designed for total coverage of the earth.
Similar orbits, similar inclinations, but still radically different relative inclinations. They arent all lined up in one big disk. They are in similar orbits spread out in time. So they are still aproaching each other at speed.
I agree there are a lot of useful orbits, but the most useful orbits like Geosynchronous orbit look like a thin donut/torus and have a lot of satellites all have the nearly the same vector just time shifted.
GPS satellites for example have basically a hot spare that can easily replace another satellite in each of the 6 planes. So, if you start out next to one GPS satellites there are 4 more you can easily reach. AKA visiting all 33 active ones would take 5 major burns, and lot's of tiny ones.
Sure, after a collision you can end up with a shotgun blast that would take a lot of effort to de orbit. But, having say 20 tugs that all deorbit the largest debris but getting them to LEO is a lot more manageable than you might think.
PS: The very tiny stuff is cleaned up by the solar wind over time and mostly not a problem in the first place.
Exactly. The tiny stuff can also be decelerated by solar wind and other random forces and fall back into the atmosphere.
The larger stuff on the other hand can cause serious impacts by transferring its momentum to the site of impact and causing damage to spacecraft.
An elastic net would let the small stuff zing around it while it could be deployed to pick up the larger stuff, by moving slightly fasted than geosynchronous orbit. Then it can actually toss them in various directions either slightly towards our atmpsphere or slightly away from Earth, to adjust its own course without expending fuel.
We could literally write a navigation program that would guide it on a path to clean up a lot of major debris this way without expending much fuel. It would only need its power for the tossing, which could be done with small explosions or mechanical pushes. The small stuff wouldn't alter its course much and the AI could correct it. Plus since it's in near earth orbit we could send updated routes to it.
Is anyone interested in writing code to route such a "space bot" by collecting and throwing stuff in various directions? We can simulate it in a 3D simulation with virtual random garbage of various sizes orbiting a planet.
Then you could present this sim to NASA or the Chinese space agency and make some big bucks :)
Geostationary orbits have no physical debris problems. There is far more real estate up there and relative speeds far less. Only a few low orbit groups share an exact orbit. Even sats launched on the same rocket drift into different planes over years unless they actively work to stay together.
To be clear, the near earth part of LEO gets cleared from simple drag though slower with increasing altitude. And even MEO is reasonably safe simply because we have yet to put a lot of junk there and there is more room.
So, even if the orbits where random you could simplify the problem by just sending more craft which would then need a smaller range of orbits. But, even within that model things are still far from random even though you will get a lot of drift over time.
Mag sails don't work in low orbits. The potential thrust they might generate is far lower than aerodynamic drag of such a large object. The magnetic field of the sail interacts with, collides with, charged particles of the upper atmosphere. Sails are only viable far away from any hint of atmosphere.
If you're a satellite, could it ever be effective to use active radar to detect small, fast incoming debris and smack it with a laser? There's obviously a question of power, but do we even have good enough sensors and weapons? Can you get enough warning to react in time, without making it worse?
That's a neat idea, but it misses an important step: after the laser hits the debris, what's changed? Now instead of a small piece of cold metal coming at you, you have a very hot blob of molten metal moving at roughly the same direction and speed.
My idea was that you get a rapidly spreading cloud of metallic vapor coming your way. Again, though, power. Also what maxerickson said, but then you need to be even more precise, at least if it's coming right at you.
That does require it to expend precious propellent though. Perhaps what we need are satellites built in shapes that allow them to turn and dodge debris using only gyroscopic attitude control
It would take a LOT of junk and a lot of money and time to ruin all orbits.
Even LEO is at least as big as the surface of the earth, and getting debris to stay in that orbit for more than a few months takes thrusters to keep it from decaying.
You could do this pretty easily. All orbits at the same altitude eventually intersect, and high LEO orbits take decades or more to decay. Moreover, at orbital velocities, even tiny fragments can destroy a satellite.
So if you fill an altitude range with enough orbiting shrapnel, you can ruin the party for everyone. The movie 'Gravity' has some breathtaking visuals of how such a runaway event would look.
Collisions are rare, but half of all near-misses today are caused by debris from just two incidents. In 2007, China destroyed one of its own satellites with a ballistic missile. In 2009 an American commercial communications satellite collided with a defunct Russian weather satellite.
There are only a handful of nations with the launch capabilities, but if any one of them wanted to ruin the party for everyone, they could probably accomplish it by hitting a few satellites with a few missiles. I don't imagine it would take very many destroyed satellites to create a serious debris hazard.
Just like all externalities, addressing the challenge comes down to who is willing to pay for it and the resultant free rider problem.
There would be obvious value in creating a space junk collection/elimination capability, but the expense when compared to the individual offset/mitigation solutions, keeps everyone from being the first mover on this.
It's clearly not a big enough problem for there to be enough economic incentives to solve it.
There are only a handful of countries with the capabilities to launch things, there are essentially no entrenched interests who benefit from space debris, and the science is rather clear. I think this is substantially easier than other purported free-rider problems that have been solved by international agreement, e.g., the ozone layer.
Anyone curious can download the current space catalog from https://www.space-track.org (signup is required). It's a good resource if you want access to formatted data about what's up there, and where.
How about autonomous satellites which cannibalize space junk's orbital velocity to de-orbit the junk, and maintain the satellite's orbit?
Imagine, a satellite is collecting space junk it encounters, and compressing a big spring using solar power. Once it gets enough junk, it launches the junk backwards, giving it momentum and sending the junk into an unstable orbit.
Rather than a spring, a coil gun would work with any conductive material quite effectively. I imagine that the difficulty is repeatedly changing orbits - this will probably require more propellant than can be derived from junk.
I was wondering if SpaceX couldn't use its second stages to grab some junk while it is deorbiting. That would be some seriously good publicity.
I wonder if there's a way to collect and recycle it, especially the larger objects, since from what I know aerospace components contain plenty of exotic/expensive materials.
I have a picture in my head of a fleet of Katamari Damacy inspired satellites gobbling up space debris using magnetic 'glue' and ejecting wads of collected mass back to earth as part of moving to new paths that will intersect debris fields. Occasionally a space vehicle grabs hold of the growing debris ball and moves it to another orbit that needs to be vacuumed.
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[ 5.8 ms ] story [ 112 ms ] threadSad when you think about it.
The point of Kessler syndrome is that it's an exponential growth in number of objects.
Niel's statement is analog to saying "The LHC could create a black hole that kills us all". Yeah... I guess on some theoretical level it's possible... but it's extremely unlikely. Same concept applies here. I'm quite disappointed in him saying "There's a very good chance", because that is far from true.
https://youtu.be/PhHtBqsGAoA?t=6285
https://en.wikipedia.org/wiki/Kessler_syndrome
And, if you speak German, yesterdays "Sternengeschichten" podcast by Florian Freistetter is about this problem:
http://scienceblogs.de/astrodicticum-simplex/2017/04/07/ster...
https://en.wikipedia.org/wiki/Kessler_syndrome#In_fiction
It is excellent though
The moon breaks in half in the first page, but a cascade event happens about a hundred pages into the book, then further changes happen :) . So I think it is accurate to say that it is analogous!
The relative speeds of any two objects in low orbit means that physically catching much of anything is horribly inefficient. The DeltaV requirements for a robot grabbing one thing, then moving to grab another, means you are probably better off launching a separate robot for each target. Any complete answer must therefore involve some means of moving debris without physically touching it. Magnets and lasers are the only hope.
Polar orbits are something of an exception, as are consolations designed for total coverage of the earth.
GPS satellites for example have basically a hot spare that can easily replace another satellite in each of the 6 planes. So, if you start out next to one GPS satellites there are 4 more you can easily reach. AKA visiting all 33 active ones would take 5 major burns, and lot's of tiny ones.
Sure, after a collision you can end up with a shotgun blast that would take a lot of effort to de orbit. But, having say 20 tugs that all deorbit the largest debris but getting them to LEO is a lot more manageable than you might think.
PS: The very tiny stuff is cleaned up by the solar wind over time and mostly not a problem in the first place.
The larger stuff on the other hand can cause serious impacts by transferring its momentum to the site of impact and causing damage to spacecraft.
An elastic net would let the small stuff zing around it while it could be deployed to pick up the larger stuff, by moving slightly fasted than geosynchronous orbit. Then it can actually toss them in various directions either slightly towards our atmpsphere or slightly away from Earth, to adjust its own course without expending fuel.
We could literally write a navigation program that would guide it on a path to clean up a lot of major debris this way without expending much fuel. It would only need its power for the tossing, which could be done with small explosions or mechanical pushes. The small stuff wouldn't alter its course much and the AI could correct it. Plus since it's in near earth orbit we could send updated routes to it.
Is anyone interested in writing code to route such a "space bot" by collecting and throwing stuff in various directions? We can simulate it in a 3D simulation with virtual random garbage of various sizes orbiting a planet.
Then you could present this sim to NASA or the Chinese space agency and make some big bucks :)
So, even if the orbits where random you could simplify the problem by just sending more craft which would then need a smaller range of orbits. But, even within that model things are still far from random even though you will get a lot of drift over time.
https://en.wikipedia.org/wiki/Kessler_syndrome#Avoidance_and...
https://en.wikipedia.org/wiki/Laser_broom
I guess it isn't something that would be on lots of satellites. But it wouldn't need to be.
Additionally, I wonder if nations with things in orbit have also considered that possibility.
It would take a LOT of junk and a lot of money and time to ruin all orbits.
Even LEO is at least as big as the surface of the earth, and getting debris to stay in that orbit for more than a few months takes thrusters to keep it from decaying.
So if you fill an altitude range with enough orbiting shrapnel, you can ruin the party for everyone. The movie 'Gravity' has some breathtaking visuals of how such a runaway event would look.
From the article:
Collisions are rare, but half of all near-misses today are caused by debris from just two incidents. In 2007, China destroyed one of its own satellites with a ballistic missile. In 2009 an American commercial communications satellite collided with a defunct Russian weather satellite.
There are only a handful of nations with the launch capabilities, but if any one of them wanted to ruin the party for everyone, they could probably accomplish it by hitting a few satellites with a few missiles. I don't imagine it would take very many destroyed satellites to create a serious debris hazard.
https://www.reddit.com/r/CredibleDefense/comments/62n21j/wha...
There would be obvious value in creating a space junk collection/elimination capability, but the expense when compared to the individual offset/mitigation solutions, keeps everyone from being the first mover on this.
It's clearly not a big enough problem for there to be enough economic incentives to solve it.
https://www.youtube.com/watch?v=vKW-Gd_S_xc
Imagine, a satellite is collecting space junk it encounters, and compressing a big spring using solar power. Once it gets enough junk, it launches the junk backwards, giving it momentum and sending the junk into an unstable orbit.
I was wondering if SpaceX couldn't use its second stages to grab some junk while it is deorbiting. That would be some seriously good publicity.