Active debris removal (harpoon satellites, magnet arms, whatever) are not a solution to this problem and are a huge waste of money. These missions answer the question "could one dock with debris and deorbit it?" To which the answer is "obviously yes, but at enormous cost" and you don't need to spend 50M euros to prove it.
The answer is exactly what governments and industry have been doing for at least two decades now. Tracking of in-orbit objects, coordinated conjunction response, and rules that require either manual or drag-induced reentry cleanup at the end of a mission. Active maneuverable satellites in orbit (like Starlink) aren't a fundamental problem. The number of objects has gone up significantly, but the big actors are coordinating and following good practices.
> Active debris removal (harpoon satellites, magnet arms, whatever) are not a solution to this problem and are a huge waste of money.
This is wrong because it's based on a flawed assumption.
That assumption being: Propellant is required to deorbit debris, and the rocket equation makes launching all that propellant prohibitively expensive.
And while we can't do anything about the rocket equation, we don't actually need to have propellant in space to deorbit things.
Ways to deorbit without propellant in space:
1. The ground based methods. Although these would likely be seen by superpowers as military escalation of the status-quo.
2. Propulsion-less drone satellites. All propulsion-less designs use some form of sail which can be used to change the drone's orbit to match the debris before latching on and towing it to a new orbit. Once the debris is now in a decaying or graveyard orbit, the drone can detach and go after it's next target. All that is needed is time, power (readily accessible via solar power this close to the sun), and reaction wheels (which now we know what caused previous designs to fail like in the Kepler mission, can be built to last).
The most common form of sails would be solar sails, but there's also EDTs and magnetic sails.
What about ablation and/or ablative thrust using lasers?
You'd need to fuel a laser platform, but it could target debris over a huge region. The goal would be to both reduce size and to gently nudge smaller debris to lower (and atmosphere-intersecting) orbits.
I'd argue that even propellent-less deorbit devices are a waste of time. The best answer is what we're doing now: rules about deorbit capability and orbit lifetime, as well as debris production. Even when there are failures, as long as they are a small enough percentage of the pie, debris won't accumulate faster than it clears.
Additionally, all the propellant-less solutions are low-thrust (or ground-based, which is another thing entirely). It's absolutely possible to orbit match, dock, and deorbit an object, but whatever low-thrust device you're using is going to deorbit as well. Maybe it's possible to launch a bunch of small devices like this to do cleanup, but it's not necessary or worthwhile.
This is a great example of a solution that sounds fun and interesting to a problem that's easy to understand at a surface-level. It gets attention and funding, but the real unsexy stuff (tracking, monitoring, collision avoidance) is where the money should go.
> The answer is exactly what governments and industry have been doing for at least two decades now.
To a degree. It helps to not blow shit up, in weapons tests or otherwise. These tests arise due to the weaponization of orbit (specifically), so the goal is really to not weaponize orbit - which governments have been doing the exact opposite of. All nations are deciding to tear Solomon's baby to shreds, instead of having shared custody.
If people want to weaponize space then, sure, go right ahead.
Unless the status quo drastically changes, i.e. bickering old fools being voted out (or removed via other means where voting is not possible/fair) throughout the world, Kessler syndrome is inevitable. I'd wager it happens sooner than runaway global warming.
> These missions answer the question "could one dock with debris and deorbit it?" To which the answer is "obviously yes, but at enormous cost" and you don't need to spend 50M euros to prove it.
Well, it's not about debris, it's about the capability to sneak up to an enemy satellite and disrupt it without outright destroying it or making it look like a failure.
Shooting a satellite with a rocket ("ASAT") is easy enough - the US, China, Russia and India have proven that capability, and Israel likely has it as well. EMPs from nuclear blasts are another option. But either of that leaves undeniable traces (an EMP blast would likely fry a lot of stuff on the ground!) and the debris can endanger your own satellites as well, so you need something that acts in-space, preferably very difficult to observe from Earth. And something that can grab a dead satellite and drag it out of orbit can also just go and deposit a small explosive charge.
And at that point, 50 million euros are chump change to test that capability - if needed, replace the magnet/hook/whatever with a bomb and that's it.
And make sure that even in the most unhappy cases, you vent your tanks! Vent vent vent vent! Tank explosions are where the really nasty debris numbers come from.
What do you do with the added deltaV from the venting? (not sure if significant)
It could send the already-out of control rocket stage/object to a weirder or worse orbit, increasing the changes of collision.
Starlink have a number of debris problems, including pieces hitting the ground, so I wouldn't say that they're actually following through with their good practices.
I think that there were no reported cases of Starlink debris hitting the ground (they're designed to burn up in atmosphere). There was a case of SpaceX's Dragon parts hitting the ground lately, but that's a different thing. Also debris hitting the ground is a different issue than debris in orbit, with different problems to solve - you can have a satellite that has 0 chance to hit the ground, while being a serious hazard in space. It's in SpaceX best interest to not leave debris in orbit, because any debris from Starlink would be a threat to Starlink itself.
Starlink doesn't have a debris problem thanks to the low orbit. Any debris generated deorbit on time-frames of a few months to a free years. Starlink also has 0 reported Earth debris strikes that I can find.
I guess talking about Kessler Syndrome is worth while here. A chain reaction where one collision, leads to more, which leads to more. It may be a slow motion chain reaction.
No one wants to de-orbit anything, because of the small chance that it hits something important on the ground, and the added fuel cost, it's easier and cheaper to just leave things in a graveyard orbit.
Maybe if starship achieves it's goals of rapid re-usability, then active debris removal could be affordable.
In the mean time it would make sense for some kind of international agreement that requires all launches plan for de-orbiting of their debris.
Graveyard orbits are not the problem. Low earth orbits are the problem.
Debris in LEO will be slowed by the atmosphere and will fall to earth naturally, but it will be dozens of decades for the higher altitude stuff and many dozens of years for all but the lowest altitude stuff.
The only feasible way to clean this up that I’m aware of, really, is to stop making new debris and wait.
If a brief moratorium (brief in geological time, like 25-50 years) was imposed, would this clear up? Or, does it descend into grey goo in space because at a threshold size, the debris can "float" on the exosphere?
Not a suggestion we call a halt on sat launches for 50 years. I'm asking if the remediation of time would work.
According to NASA: If the debris is <600km the orbit decays within a few years. >800k can take centuries and geostationary objects on the high end (~36000km) can take thousands of years.
Most of the debris is in LEO so it could take decades to centuries for the debris to clear out
So the killer move would be to launch a fleet of sats above the debris field, and then launch self-destructive sats into the persisting space dense enough to make launch and persistence in that field hard.
Take command of the high space and make the low ground indefensible.
It's essentially impossible to plot the "actual size" of debris against a full earth model. The math simply doesn't work out with the pixel density of modern screens. Actual size of debris is way smaller.
So... Complaining about a caricature when the real solution isn't possible seems silly.
I think they fully expected the second stage of Ariane 6 to be able to deorbit itself. Other than spacex, it's pretty unusual for testflights of big orbital rockets to be put on a suborbital trajectory. e.g. the first flight of SLS went around the moon.
Tethers Unlimited once considered an option of using tethers to move between orbits (using Earth magnetic field and solar cells for energy) and deorbiting debris.
Tangentially related: Could this be weaponized? What's stopping a malicious actor from purposely creating a lot of debris in orbital space for the purposes of knocking communications down? Is there a plan in place?
Sure, but it’d be a hell of a lot easier for said actor to attack infrastructure on the ground, like an oil rig, and the powers that be don’t take kindly to that sort of thing, either. Before anyone could do any outsized damages they’d have their manufacturing lines, launch platforms, and any citizen with an aerospace degree pulverized.
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The answer is exactly what governments and industry have been doing for at least two decades now. Tracking of in-orbit objects, coordinated conjunction response, and rules that require either manual or drag-induced reentry cleanup at the end of a mission. Active maneuverable satellites in orbit (like Starlink) aren't a fundamental problem. The number of objects has gone up significantly, but the big actors are coordinating and following good practices.
This is wrong because it's based on a flawed assumption.
That assumption being: Propellant is required to deorbit debris, and the rocket equation makes launching all that propellant prohibitively expensive.
And while we can't do anything about the rocket equation, we don't actually need to have propellant in space to deorbit things.
Ways to deorbit without propellant in space:
1. The ground based methods. Although these would likely be seen by superpowers as military escalation of the status-quo.
2. Propulsion-less drone satellites. All propulsion-less designs use some form of sail which can be used to change the drone's orbit to match the debris before latching on and towing it to a new orbit. Once the debris is now in a decaying or graveyard orbit, the drone can detach and go after it's next target. All that is needed is time, power (readily accessible via solar power this close to the sun), and reaction wheels (which now we know what caused previous designs to fail like in the Kepler mission, can be built to last).
The most common form of sails would be solar sails, but there's also EDTs and magnetic sails.
You'd need to fuel a laser platform, but it could target debris over a huge region. The goal would be to both reduce size and to gently nudge smaller debris to lower (and atmosphere-intersecting) orbits.
(As mentioned in another comment, linking: <https://en.wikipedia.org/wiki/Laser_broom>, here: <https://news.ycombinator.com/item?id=41051533>.)
Additionally, all the propellant-less solutions are low-thrust (or ground-based, which is another thing entirely). It's absolutely possible to orbit match, dock, and deorbit an object, but whatever low-thrust device you're using is going to deorbit as well. Maybe it's possible to launch a bunch of small devices like this to do cleanup, but it's not necessary or worthwhile.
This is a great example of a solution that sounds fun and interesting to a problem that's easy to understand at a surface-level. It gets attention and funding, but the real unsexy stuff (tracking, monitoring, collision avoidance) is where the money should go.
And more importantly, just having laws that require people to deorbit sats and force them to pay for deorbit if they fail to make something deorbit.
> 2. Propulsion-less drone satellites.
Nowhere near enough thrust for this.
The dress would not survive unscathed, and neither would the solar sail.
To a degree. It helps to not blow shit up, in weapons tests or otherwise. These tests arise due to the weaponization of orbit (specifically), so the goal is really to not weaponize orbit - which governments have been doing the exact opposite of. All nations are deciding to tear Solomon's baby to shreds, instead of having shared custody.
If people want to weaponize space then, sure, go right ahead.
Unless the status quo drastically changes, i.e. bickering old fools being voted out (or removed via other means where voting is not possible/fair) throughout the world, Kessler syndrome is inevitable. I'd wager it happens sooner than runaway global warming.
Well, it's not about debris, it's about the capability to sneak up to an enemy satellite and disrupt it without outright destroying it or making it look like a failure.
Shooting a satellite with a rocket ("ASAT") is easy enough - the US, China, Russia and India have proven that capability, and Israel likely has it as well. EMPs from nuclear blasts are another option. But either of that leaves undeniable traces (an EMP blast would likely fry a lot of stuff on the ground!) and the debris can endanger your own satellites as well, so you need something that acts in-space, preferably very difficult to observe from Earth. And something that can grab a dead satellite and drag it out of orbit can also just go and deposit a small explosive charge.
And at that point, 50 million euros are chump change to test that capability - if needed, replace the magnet/hook/whatever with a bomb and that's it.
If it works, and if it gets cheaper as the technology matures, it might let use remove derelict satellites before they break up into smaller pieces.
It is usually easier to remove a few thousand big pieces of trash than to remove millions of small pieces of trash.
Starlink doesn't have a debris problem thanks to the low orbit. Any debris generated deorbit on time-frames of a few months to a free years. Starlink also has 0 reported Earth debris strikes that I can find.
Where do you get this misinformation from?
https://en.wikipedia.org/wiki/Kessler_syndrome
We definitely do need a way to clean things up, it is a shared resource. Unfortunately that means it suffers from tragedy of the commons.
Maybe if starship achieves it's goals of rapid re-usability, then active debris removal could be affordable.
In the mean time it would make sense for some kind of international agreement that requires all launches plan for de-orbiting of their debris.
Debris in LEO will be slowed by the atmosphere and will fall to earth naturally, but it will be dozens of decades for the higher altitude stuff and many dozens of years for all but the lowest altitude stuff.
The only feasible way to clean this up that I’m aware of, really, is to stop making new debris and wait.
Not a suggestion we call a halt on sat launches for 50 years. I'm asking if the remediation of time would work.
Most of the debris is in LEO so it could take decades to centuries for the debris to clear out
Take command of the high space and make the low ground indefensible.
A rule they just violated on the return-to-flight of Ariane 6.
I also hate the cover photo. That's not the actual size of the debris.
So... Complaining about a caricature when the real solution isn't possible seems silly.
But grounding humanity is bad for everybody. GPS and weather satellites are nice.