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.
You don't need to put a laser in space to do this.
You build a ground based laser, and fire it at objects when they're approximately directly overhead. Pushing upwards on the object basically rotates it's orbit so one side of it will not be lower into the atmosphere.
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.
Depending on how far costs fall, one potential problem would be an equivalent of "flags of convenience" in sea-based shipping. Small countries with little or "favourable" (e.g., short-term profits) regulatory regimes could sustain at least some launch capability. Unless there's some way of reining in that activity, I see the problem manifesting to at least some degree.
Even now, getting launch-capable countries on board with restrictions is a likely problem. The US, EU, and Japan perhaps not so much, but of Russia, China, India, Pakistan (potentially), and North Korea, rather more plausibly.
Most of the countries named are already under heavy sanctions, and have proved resilient against them to a large extent.
One problem with the Kessler Syndrome is that it's a runaway phenomenon, though one that evolves more slowly than most people appreciate. A few bad actors could trigger events which slowly start to seriously degrade at least low-to-mid Earth orbital ranges.
Geosynchronous orbits are possibly less susceptible as the entire orbital ring is large, though geostationary orbital space, strictly along Earth's equator, is more constrained. The Starlink approach of putting comms satellites in very low Earth orbit, which clears fairly quickly, possibly mitigates this in two ways (it makes geosync less critically necessary, and de-orbits satellites quickly). But LEO is still where higher orbits eventually decay to, and might itself be affected with time as well.
The lax regulatory problem, which invokes another underappreciated economic principle, Gresham's Law, is one that's appeared elsewhere and has proved hard to counter. I'd suggest not underestimating its possible noxious effects.
If solar sail probes can change their orbits over time (which they can), then they already have enough thrust. There's no static friction to overcome, so there isn't a minimum thrust that you need to reach.
As long as you can continue to apply thrust over time, then you have a solution.
It doesn't matter if it takes 6 hours, 6 weeks or 6 months. Even a single probe moving the right piece of debris prevents tens of thousands of more pieces being generated. Imagine what three of them could do, or twenty...
A solar sail isn't a pressure vessel, fuel tank, electronics bay, or other sensitive instrument. It can take considerable abuse before being substantially degraded, let alone failing.
Space debris impacting on a solar sail would all but certainly simply punch neat holes through it. Much as accumulating dust slowly degrades the light-gathering capability of a large reflector telescope, a modestly-perforated solar sail would lose a very small fraction of its effectiveness. But you could probably lose a heck of a lot of surface area before those effects became significant. Strength of the sail itself is probably a minimal concern, though a design with periodic reinforcing threads (themselves having a cost of increased mass) might be more than sufficient to address any strength compromise.
the solar sail would need to be incredibly large for a craft that can move to arbitrary locations in orbit for the purposes of de-orbiting satellites, which means it must have large sails so that both the de-orbiter and the de-orbitee can both be moved via sunlight alone, and achieve the required thrust vector in a reasonable amount of time (this de-orbiter must de-orbit many satellites, remember?)
the larger the sail is, the more likely it is to be affected by space debris at any given moment.
debris passing through a taught mylar solar shield will tear holes in the mylar which are the shape of the debris passing through. any sharp corners in the debris will leave a sharp corner in the hole, and those corners are going to become tears the next time something passes through nearby. the tiny holes become large holes pretty quickly.
other materials will behave differently of course, but i don't know of any solar sails at all, never mind ones made out of not-mylar.
> 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.
The way a laser broom works is imparting an extremely miniscule bit of momentum every time the object is in line of sight of the laser. Over time you lower its orbit enough for atmospheric drag to take over. For small debris, like baseball sized chunks of insulation, it takes months to deorbit the objects. For something the size of a satellite it would take an order of magnitude longer than the life expectancy of the satellite, and that's assuming it does no station-keeping.
Laser brooms are great because they can deorbit a lot of debris in parallel, which is great if your goal is to slowly clean up an orbit. They are pretty much the worst option for deorbiting a specific object quickly which is a hard requirement for any anti-satellite weapon.
Makes sense but are there actually limits that prevent the scaling? IE instead of a single laser broom I build 50 near a solar/nuclear plant and use the surplus energy. Usually they all deorbit different objects but I could choose to aim them all at the same object.
I don't see much of a limit to scale. Satellites can only dissipate so much heat so you don't even have to deorbit it to be successful, you just need impart enough energy to overheat the satellite or disable key parts.
A single broom for debris clearing is an immense project - likely $500 million to $1 billion to construct. It is basically a big observatory telescope with a gigantic high power laser - it is large, fragile, and completely immobile. That's for slowly cleaning up an orbit, to scale up to a weapons system you'd need a system equivalent to building tens of thousands of them.
You're not building a weapon system with surplus energy. Energy costs are actually pretty negligible - with 0.01% electric to kinetic efficiency it's only about 7 million dollars worth to bring down a 1000 kg satellite. The issue is the equipment. To deorbit that satellite in a year, you would need to on average be pumping 7.8 gigawatts of electricity into the system. If you put literally all of the US's electricity production into it, you could deorbit that single satellite in 2.4 days. And note that is if you could constantly keep the satellite in field of view, realistically only a small percentage of a satellite's orbit will be even under the best of circumstances, and many orbits won't be in view at all.
Yeah, there's nothing physically stopping someone from building such a system, but you're talking about putting basically all of a large nation state's GDP for decades into one weapon system that, in the best case scenario, is going to do an extremely minute amount of damage and realistically would be destroyed long before it could accomplish anything.
Disabling a satellite poses different technical challenges. For momentum transfer, so long as you're hitting the object you're good, to target critical systems would require far greater precision, and dumping heat faster than the satellite can dissipate it would require even higher instantaneous power. Remember the satellite is only very briefly in view. While this is almost certainly more feasible than a weapon that works by deorbiting, it is still very difficult. Laser weapons for disabling and destroying aircraft and airborne munitions, which is an inherently easier task, is an active field of research that many billions of dollars have been dumped into over the years, with no system yet being demonstrated as effective. Satellites are just faster moving, more distant targets for such systems.
ASAT missiles might be too mundane for the megalomaniac Bond villain, but they are an immensely more practical solution to the problem.
> 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.
Ideally you have several vents perpendicular to the orbital path and open them at the same time, so the vectors cancel out. That's the happy case. If, because we are in the sad case, we can't get that, it's still better to have one piece of debris versus thousands.
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.
Just read a fiction book that had this as the premise in a war between china and the USA. China took the high orbits and blasted the low. Personally I thought it was a a very interesting twist!
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.
You would not be attracting stationary objects, you would be attracting things flying past at tens of thousands of whatever unit per hour you like best. Gravity is nowhere near strong enough to affect these objects for purposes of collecting them.
There are regulations around de-orbiting your spacecraft at end-of-life, and there are international agreements around weapons in space that refer to the generation of debris.
I don't understand how a lack of regulation would mean something isn't a big problem. It could for sure use much more regulation, as it is such a large problem.
Seems similar to the angst when SpaceX launched the first constellation of satellites and astrologers cried that their images would be ruined because the sats are visible on long exposure shots. There was some initial backlash, then total silence. Perhaps because there are no follow-up articles, so the whole debacle seems like theatre to the layman.
If ESA is "lacking innovation" I wonder what your favorite space agency innovated compared to them in the past decade.
But yes, let's keep polluting more and more the low-Earth orbit to make sure we cannot send any more satellites ever again! You are lacking intelligence.
The vast majority of the debris is from China and Russia irresponsibly disposing of waste and testing weapons but I see no mention of them in the article. The only cause is a thinly veiled reference to SpaceX. Controlled satellites in LEO, whether you like it or not, are not orbital debris. It's a classic hit piece.
Those de-orbit in just a few years because of how exceptionally low they fly. SpaceX’s business plan is to just be so efficient at launching things to orbit that it doesn’t matter if they lose a huge number of satellites each year to planned atmospheric drag. It’s a pretty bold way of combating space junk, but it seems to be working out for them, and the FAA has looked over the math and given their blessing.
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.