Getting Rid Of All The Space Junk In Earth’s Backyard

Space, as the name suggests, is mostly empty. However, since the first satellite launch in 1957, mankind began to populate the Earth orbit with all kinds of spacecraft. On the downside, space also became more and more cluttered with trash from defunct or broken up rocket stages and satellites. Moving at speeds of nearly 30,000 km/h, even the tiniest object can pierce a hole through your spacecraft. Therefore, space junk poses a real threat for both manned and unmanned spacecraft and that is why space agencies are increasing their efforts into tracking, avoiding, and getting rid of it.

Earth Orbit is Getting Crowded

A computer-generated image of the space debris around Earth. The two main debris fields are the ring of objects in geosynchronous Earth orbit and the cloud of objects in low Earth orbit.
Credit: NASA image, Public Domain

According to NASA’s Orbital Debris Program Office (ODPO) Earth orbit currently hosts an estimated number of 500,000 marble-sized debris objects and a whopping 100,000,000 objects of 1 mm or smaller. As shown in the picture there are two main debris fields. While most of the debris is located in low-Earth orbit (LEO) at altitudes of <2000 km, there is also a ring of space junk in geosynchronous orbit (GEO) at an altitude of ~36,000 km.

Space trash includes derelict spacecraft like the Vanguard I satellite which has been in orbit for over 60 years and thus holds the record for the oldest man-made object in space. Other culprits are upper stages of rockets that broke up or exploded, which is why nowadays they are usually “passivated” by venting their unburned fuel.

In 2007, China earned a lot of criticism for blowing up their Fengyun-1C weather satellite as part of a missile test. Together with the accidental collision of the US communications satellite Iridium-33 and the defunct Russian Kosmos 2251 satellite in 2009, these events are responsible for much of the large debris currently located in orbit.

To protect themselves from micrometeorites and orbital debris (MMOD), spacecraft use so-called Whipple shields consisting of several thin layers that are spaced apart. Upon impact, the outermost layer shatters the projectile thereby spreading its kinetic energy upon a large area as it passes through. To avoid collisions with known larger objects, spacecraft sometimes have to perform evasive maneuvers.

For the ISS, such a maneuver is ordered if the chance of impact is greater than 1/10,000 which happens on average once per year. In 2012, a record number of four of such moves had to be performed which are always costly because of the large amount of fuel that needs to be spent. NASA’s space shuttles have frequently been pierced by MMODs, but luckily all of the catastrophic collisions so far have been limited to unmanned spacecraft. One example is that of the French satellite Cerise which was hit in 1996 by part of an Ariane rocket booster. And we’ve already mentioned the Iridum-Kosmos crash.

Keeping Track of All the Junk

It is vital to catalog and track all the junk floating around in orbit to prevent future crashes, and to prevent future crashes from further contributing to the space junk problem. The most comprehensive catalog of space is junk is held by the US Space Surveillance Network (SSN). Currently, they keep track of more than 22,000 man-made objects orbiting Earth that are 10 centimeters or larger.

Depending on their altitude, objects with sufficient size can be detected by ground-based radar and optical telescopes. Optical telescopes measure the sunlight reflected by debris, while the distance can be accurately determined by laser ranging. The method is based on measuring the round trip time of a short laser pulse shot from the ground and reflected by the object. The technique has long been used to track satellites that are equipped with a retroreflector. Since the diffuse reflection from space debris is much fainter, the measurement is significantly harder. So far the technique could only be used during twilight when the laser ranging station on Earth is in darkness but debris objects are still lit up by the Sun. With improved imaging techniques, Austrian scientists just recently succeeded to use space debris laser ranging during the daytime, doubling the viewing window.

A panel from the Long Duration Exposure Facility (LDEF) spacecraft showing numerous holes from orbital debris.
Credit: NASA JSC

NASA’s Long Duration Exposure Facility (LDEF) taught us a lot about space debris. It was essentially a target that was left in space for about six years before it was retrieved by the Columbia Space Shuttle in 1990. The LDEF hosted 57 individual scientific experiments designed to study the long-term effects of outer space environment on different materials, electronics and biological samples. Because of its large surface area and long exposure, much statistical information was gained from studying the Swiss cheese pattern that had formed on its surface as shown in the picture.

Cleaning up the Orbit

Since 2002, all major space agencies are following some common guidelines to reduce the growth of space debris. Spacecraft in GEO are required to move to a graveyard orbit at a higher altitude after they finished their mission. Objects passing through the LEO region should be de-orbited or at least put into an orbit with a reduced lifetime.

Due to atmospheric drag, all orbital debris will eventually fall back to Earth. However, at altitudes of 800 km, this may take decades, while above 1,000 km orbital debris normally will continue circling Earth for a century or more. We’re adding space junk faster than it’s raining down. Therefore, in the long run, we not only need to stop the ongoing pollution of space but also actively get rid of some of the space trash already in orbit. Otherwise, the density of debris may become large enough to create a cascading effect where the fragments created in a collision trigger new collisions. This scenario is known as the Kessler syndrome and nicely explained by Donald Kessler himself in this video.

Space Lasers

Concept for the de-orbiting of space junk using a high-power laser.
Credit: C. R. Phipps et al.

Plans for the active removal of space debris include the ClearSpace-1 mission of the Swiss startup ClearSpace which was funded by ESA and is planned to launch in 2025. ClearSpace-1 will use robotic arms to capture part of a Vespa (Vega Secondary Payload Adapter) upper stage left in orbit from a previous ESA mission. Both spacecraft will then be deorbited to burn up in the atmosphere. Eventually, the goal is to have a “tow truck” in space that can capture and remove multiple objects with a single mission.

The same lasers that are used to track space junk might also be used to remove it. There are several concepts, to use high-power ground- or space-based laser systems to remove debris of 1 – 10 cm size from LEO space. The laser evaporates material from the object which forms a jet that slows down the target so that it will re-enter the atmosphere faster.

After we have already polluted Earth to a devastating degree it would be nice to not see the same thing happening in space. It would be a shame if the scientific progress and communication technologies enabled by space missions were put to a halt by the Kessler syndrome. With future new mega-constellations of satellites like the Starlink project, this risk is quite imminent.

86 thoughts on “Getting Rid Of All The Space Junk In Earth’s Backyard

    1. As it was already mentioned, China managed to populate a large portion of the junk is very short time.. by blowing up Fengyun-1C..
      ..why am I not surprised?

      I don’t see China even trying to do anything about cleanup..

  1. Big blocks of a ballistics gel like material in space?
    Perhaps not enough to stop fast objects but just slow them down. Eventually it would increase in mass with captured particles until it deorbited and burnt up on it’s own. Or perhaps a series of nested balls of chicken wire with a high static electric charge. No doubt a few military satellites have countermeasures for defence. Guess they are reluctant to turn the iss into an orbital weapons platform, and with good reason.

  2. All those words about tracking objects and no mention of either LeoLabs.space or Celestrak? Both amazing resources for keeping track of that stuff.

    And a very timely posting: LeoLabs is predicting a very high risk of two defunct satellites TONIGHT:

    Object 1: 19826
    Object 2: 36123
    TCA: Oct 16 00:56UTC
    Event altitude: 991km

    Combined mass of both objects is ~2,800kg. Equivalent energy is about 20 tons of TNT.

  3. There’s talk of new rules about space debris. Just on Tuesday the ARRL posted about its comments on the matter. The rules make sense for big commercial satellites, but become a problem for small and non-commercial satellites.

    1. Hello, do you mean this one?
      http://www.arrl.org/news/arrl-comments-in-orbital-debris-mitigation-proceeding

      I’m surprised that this causes so much trouble.”Traditionally” (I can’t believe I would say this one day), CubeSats and other experimental sats are floating around in LEO, which causes many satellites to de-orbit anyway within 10 years or so. If they collide, do they cause any real issues? Or affect sats in higher orbits? I mean, most stuff in that area is slowed down by the remaining atmosphere, anyway.

      That being said, I hope we will, someday, see “real” satellites in amateur radio again.
      Such as the Phase II types (OA-7 etc)..

  4. High powered lasers that can reliably hit orbital-speed objects 1000 km away, and deposit enough energy to ablate surfaces? Yeah…

    Like the paper abstract says: ” laser orbital debris removal (LODR) […] system will have multiple uses beyond debris removal.”

    Indeed.

      1. Nah, not really new, I think. Laser cannons are somewhat 1970s.. 🙄

        And, if memory serves, these high power lasers that measure moon’s distance are in use since the moon landings, when these mirrors were placed (last part of Apollo that’s still active or so)..

    1. Every time this topic comes up it’s a bunch of misunderstandings about the extent of the problem and then horse shit solutions that will never work. Like every dang time, it’s sad

      1. Yes, it’s amusing to read the musing of folks who don’t appreciate the energies involved. Or orbital mechanics, for that matter.

        But, actually, the ground-based laser approach is one that could really work. It’s that “dual-use technology” problem that will make it difficult to deploy. Can’t let the other guys have a technology that can take out your satellites (or airplanes) at will…

        I had a 60 megawatt Q-switched Nd:YAG laser in a previous workplace: a tiny version of the one described in that first paper. Fun stuff blasting holes in things, but kind of terrifying. Then, when you realize you need ten thousand times its pulse energy for a LODR system to work, and know that it can be arbitrarily pointed to track anything it sees, you recognize the scale of the problem. Especially when the thing can still fit in a large truck.

          1. 400 mJ. Enough to put a hole in aluminum foil or a business card. Enough to make an ionized “spark” in mid air at the focus of a 50 mm lens, or a bubble inside a piece of acrylic. It’s in “party trick” territory, even though it will promptly ruin a spot of your retina if you catch it.

            400 mJ is nowhere near enough to impart significant momentum to even a small piece of debris: you’d need many, many thousands of 1 kJ shots to do that.

        1. If you want to break satellites, there are easier ways. The soviets already tested an anti-armor rifle on board of one of the Almaz stations.

          As for shooting down airplanes inside the atmosphere, you won’t have the 1000 km range due to dispersion and absorption before you even reach the curvature of the earth. It only really works shooting the beam up from a high spot.

          1. the idea is specifically NOT to break the satellite, that just worsens the problem. the idea is to use the laser ablation of the entire facing surface as a retrorocket to destabilize the debris orbit. in LEO, a deorbiting manuver can be as low as 10 m/s because you just need to bump it into the thin upper atmosphere where it’ll get brought down by atmo drag (could still take months but it’s guaranteed to come down, sooner than later).

          2. If you have the resources to put a usable rifle in orbit, you don’t need a ground-based laser.

            But how do you get that rifle where you need it? Putting it in a different orbit to hunt a different satellite costs just as much as lobbing up a new one. But from the ground I can hit a dozen satellites per hour with my laser, and any given satellite is going overhead at least twice a day.

            If you don’t want the complexity of a push-button laser and want instead to go cave-man style, you could just throw a bucket of ball bearings straight up in front of your target satellite and let its own kinetic energy kill itself when it hits that near-stationary wall of balls. Bonus: after that energetic momentum transfer pretty much all the debris will be sub-orbital and will rain down shortly. And you don’t need an orbital-class rocket to lift a hundred kg of marbles to 500 km altitude. Even Jeff Who’s little puddle jumping shepard is gross overkill.

            And of course it’s obvious lasers can’t hit things they can’t see (or resolve). But if you can see the whites of their eyes, they’re eligible.

          3. not a rifle but a modified 23mm revolver cannon…the projectile is 67g and muzzle velocity about 850 m/s, the cannon is able to spit between 1800-2000 rpm, so you can imagine there’s quite the thrust from firing it…also the normal variant of the cannon weighs 58.5kg…

        2. ground based would only push away which would cause even more issues

          only way to clean it up is to start at the lowest level and draw them down

          regardless, one tiny screw up in the clean up process and you’ve just locked us to this planet for 100 years AND without satellites

          there goes your mtv kids!

          1. that’s not how orbital mechanics work…pushing “up” would be “+ radial”, what that basically does is it starts to rotate the imaginary ellipse of the orbit in plane with the pivot point on the satellite, pushing one side of it higher and one lower to the atmosphere.
            For a higher orbit you need more speed – push “forward” ;-)

        1. Pretty sure the reference was to the forgettable “Real Genius”.
          I remember, because that was the year I put a hole in my own hand with a laser. Seriously. An accident, but still really stupid.

          1. I thought it was a reference to “Red Planet”, where at the end of the movie the lady says that the long time to return to Earth will give her “to get to know the janitor”.

          2. “Forgettable”?!
            That was one of the greatest cheeseball movies of all time! You take that back, or I’ll get the boys to bury your house in popcorn!! LOL

    2. Well, the objects they’re aiming at are light and don’t need much of a push to bring them down.

      And it’s easier to shoot a laser up through a thinning atmosphere than shoot it sideways at the ground – less absorption. Firing the laser towards anywhere but up from a mountain top would see the beam lose energy and disperse very quickly. I mean, they already have megawatt-level lasers with pinpoint accuracy developed for military purposes, but they haven’t been able to weaponize them effectively because of that little problem.

      1. If you could hoist a high powered laser into LEO and track nearby debris, I wonder how many orbits you could change before your batteries ran out. Since you wouldn’t have to worry about atmospheric dispersion and the objects would be a lot closer, you could reduce the power per shot allowing you to hit more targets. It would be really interesting to see a cost/benefit analysis between ground and space based lasers for this kind of thing

      2. “And it’s easier to shoot a laser up through a thinning atmosphere than shoot it sideways at the ground – less absorption. Firing the laser towards anywhere but up from a mountain top would see the beam lose energy and disperse very quickly.”

        How tall would your mountain have to be to deliver a significant advantage? Bear in mind that you can’t go to The Mountain Store and get a new one.

        1. It’s not absorption that’s the problem, it’s defocusing due to atmospheric “turbulence” (stochastic density variation) (and other effects, to be pedantic).

          Plainly put: if you can’t focus on the target, you can’t deposit enough energy or power density to do any good.

          Ghez’s Nobel-winning adaptive optics notwithstanding, you’ll be doing extremely well to keep most of the beam power in a 10 cm spot through even just 5 km of sea-level atmosphere – an arcsecond or so of precision.

          Even if you find a hill (or fly) 5.5 km (18 kft?) high, where you’re halfway out of the atmosphere, it doesn’t do you any good to aim at targets below you: you’re still firing through dense atmosphere.

          No, lasers are crappy for long range near the ground. Even aiming upwards, you are much better off from a high mountain, for the same reasons optical telescopes are placed there.

          You’ll also want to be near the equator to see all LEO satellites. Kilimanjaro would be a fine place for this. Or Chimborazo. Or maybe Atacama, which already has suitable services there.

        2. Generally speaking, laser beams in atmosphere start to get absorbed and scatter after 300 meters.

          From googling around, a near infrared beam loses about 1-4% per 10 km by atmospheric scattering at sea level, and if I’m reading my coefficients right, about 10% per kilometer by absorption under average clear sky conditions.

          Which means only 2% of the near infrared light emitted up from sea level ends up in space.That’s called the greenhouse effect. Of course there are certain “windows” in the spectrum where the atmosphere is more transparent.

  5. I’ve always thought that same technology for catching objects in water should be used in space. A net. Something of high volume but low weight that will slow orbiting projectiles down or catch them. How about a foam filled balloon, that expands several kilometres across when fully inflated. Let it sit in the path of the most dense areas. Stuff collides with it and either becomes embedded or slows down so falls to earth. Of course, I know nothing about what I’m suggesting.

    1. What in water travels at 30,000 km/h ? or ~8333 meters per second (~26246.72 feet per second or ~15550 knots).

      Anything I can think of would be instantly turned to shrapnel creating even more debris.

      What is needed is something that can exactly match an objects orbital velocity, bond with the object and slow the orbital velocity enough that gravity takes over and the captured object enters a controlled basaltic trajectory where it is safely crashed into Point Nemo (Latin for “no one”) also known as Oceanic pole of inaccessibility (48°52.5′S 123°23.6′W).

    1. Unless they edited the article, the last sentence:

      > With future new mega-constellations of satellites like the Starlink project, this risk is quite imminent.

      Also, your last statement is false. Clockwise and anti-clockwise would actually result in relative speed being doubled, however most of the debris would not be orbital velocity.

      But If they are on paths at a 90 degree angle, such as equatorial and polar orbits, then they would still impact with very high relative velocity and their debris would still be orbital velocity.

    1. Shouldn’t they have thought of traffic lanes … and one way ‘streets’ so to speak :) :D . Ha!

      Yeah, any solution is going to be able to have ‘multiple’ uses. As soon as you have a ‘vacuum cleaner’ up their that can match orbits, collect junk or kick junk into a lower/highly elliptical orbits, or laser them, or whatever…. Nothing says you can’t do that with live satellites too…

  6. “After we have already polluted Earth to a devastating degree it would be nice to not see the same thing happening in space”
    Well, no. Personally I prefer not to see Earth polluted to a devastating degree, I´m not living in space.

    Anyway, a specie which is not able to care for its own home does not deserve exploring other planets and spreading its stupidity elsewhere.

    1. ‘I’m not living in space’ but you depend on it here on earth. Space is where technology is used to monitor our planet’s health. Among many other services. This misconception is very damaging. And as time goes by and we do not take action the ‘space problem’ it’s going to be the earth’s next pandemic.

  7. Hey if SpaceX’s starship becomes a reality and drives down the cost of putting things up in orbit, why bother with the laser on the ground and all the added complexity of atmospheric distortion? And if there are security issues with having high powered lasers up in space, perhaps limiting them to some sort of agreed upon low power might make everyone happy.

  8. The americans started with shooting down satellites in 1985 with an ASM-135
    (ASM = Anti Satellite Missile)

    https://en.wikipedia.org/wiki/ASM-135_ASAT

    And they did it again some time after the Chinese:
    https://en.wikipedia.org/wiki/USA-193

    Apparently India has also done so, but I have not looked further.

    Also: ISS needs to be boosted regularly to prevent it from falling down, so they are not “wasting all that fuel” to prevent debris, but just adjust the timings of the orbit boosts a bit.

  9. i think catching and macgyvering in space is the best option, lasering satellites may be how earth gets rings like saturn, and perhaps we should either drop a large magnet or 2 in the proper orbits, or mine asteroids and construct a large magnet in space.. which may lead to an extinction level event, depending on how large of a magnet ball of space debris falls to earth.

    1. effing magnets… How would that work? Especially considering there’s no way we could build a magnet with remotely as much energy as the one that already exists there (i.e., the earth field itself), and IT isn’t doing anything about the space junk problem.

      And: there’s already a several-ton magnet in orbit (the Alpha Magnetic Spectrometer). It’s been there for years. Doesn’t do a darned thing for space junk. But, to be fair, it has collected several billion pieces of antimatter so far.

      1. The best use of the earths magnetic field is to extend very long conductive wires from the capture device. That conductor by virtue of moving through a magnetic field has a current induced in it which generates a magnetic field that creates a force which opposes the direction of movement (slowing the captured device down). Eventually it will be decelerated so much that lowers its orbit height and finally burns up in the atmosphere.

        It would probably the the cheapest way of deorbiting satellites and space debris, and because of that it will end up being the one that is eventually used.
        What could possibly go wrong with a few football field lengths of wire hanging from either side of a satellite or other space debris.

  10. I have a very simple idea and cheap too! Spin a giant Nurf ball in space, let it collect debris and then fall back and burn up. You could launch a platform with the liquids and shoot out hundreds of balls, pick trajectory and away they go!

  11. Aren’t most of these pieces made of metal? Why not put a powerful electron magnet into space in a satellite that we can turn on and off from the ground. Use it to change the orbital path of objects as they fly by so that they either go 90 degrees in a new direction toward earth or out into space? The electron magnet never has to touch these objects or move itself. It simply turns on and off at the right time to alter the debris’ path into a new one that leads to its’ demise.

    1. You would either need an absurdly huge magnetic feild, or be right next to tue debris for that to work, due to the inverse square law of magnetism. If you get close enough for a reasonably sized, solar powered electromagnet to have any effect on the orbit of the debris, you might as well use something else to push it out of orbit. With good focus, I suspect a laser in orbit would have nearly the same energy at its target as it does at the source, which is more efficient than magnets. Now if it were possible to make a *magnetic* laser somehow… :D

  12. Hackers should be pushing hard for creating an L-point junkyard for these defunct space things. Much of what is put up there is very high tech, repurposable awesome Stuff… just the thing for space hackers of the future to dig thru and reuse for Cool Projects.

    Alas, Fuel is a big issue. It takes a lot of maneuvering to match orbits, snag and then lift all this Cool Stuff to that L-point. Maybe a junk ship that constantly cleans the space ways (like that net boat trying to clean plastic from the oceans) fueled by propellants harvested from moon and asteroids?

    Come on hackers! there gotta be a way! Think of all the really awesome Hackaday.space articles and projects!

  13. Space Flypaper. Big sheets of it, ballasted so that tidal effects in orbit make it stretch out radially. Make it open up to 100 meters x 100 meters.

    Then anything in orbit up to 50 meters below the flypaper’s center of mass will be orbiting slightly faster, catch up and get stuck. Anything in orbit up to 50 meters above the flypaper’s center of mass will be run up on from behind and get stuck.

    To prevent encounters with debris in an opposite direction orbit from breaking up (or breaking the flypaper) and spreading more debris, the adhesive coating would need to have zero volatile components and be extremely stretchy. Imagine shooting a bullet at a piece of flypaper and having it penetrate but the sticky coating stretches way out the back side without breaking so the bullet is captured.

    After a few days in orbit the flypaper will have a 100×100 meter ‘tunnel’ cleared around Earth then it can be deorbited, grabbing more small debris on its way down.

    For a longer duration and more cleaning, don’t put it into a circular orbit. Give it some eccentricity so as it goes around it will intersect more debris that’s also in eccentric orbits that cross the flypaper’s orbit. Every time around it will cross those other orbits at the same relative location, but due to differing orbital periods there will be different debris at the intersections. With enough passes everything in the other orbit can be cleaned up.

    Launch the flypaper cleaners by the case load, like SpaceX Starlink satellites.

    These could also be used to bring down low orbit satellites that can’t be controlled due to failure, and larger pieces of debris. Put into an orbit for a slow relative velocity intercept, the flypaper would stick and add a large amount of surface area to increase the drag from the thin atmosphere to deorbit faster. And while that’s going on the flypaper will also be snagging small debris.

  14. How about a service to put your cremated remains into space. Straight up and then straight down unless they run into something. I.e. disperse your remains in front of some space debris. Likely cheaper than a modern funeral. Too fine to cause further fragmentation.

  15. How do all orbiting objects naturally de-orbit? Atmospheric drag, right? So why not artificially create temporary additional atmospheric drag in narrow bands to de-orbit rogue items large and small? A bubble of air, launched in westerly LEO at such height and speed as to de-orbit itself within months, would act as an atmospheric brake to bring down everything in its path not able to maneuver away from it. A bubble of ordinary sea-level air, chilled to liquidity at -200 C, has 1/700 its volume, and expanded naturally in space to vastly greater volume and lower density, would, over weeks or months at a closing speed of over 50,000 KPH and 30 impacts/day at LEO, have enough kinetic energy to de-orbit all the the easterly-orbiting objects in its path. Everything from spent boosters and dead satellites to paint flecks and stray bolts, all potentially destructive at orbital velocities, would be slowed and de-orbited in time. Active satellites, duly alerted, could plan to maneuver themselves away from the cloud until it safely dissipated and deorbited.
    This ought to pass the needed tests of being thorough, practical, economical and scalable. For example a 4 meter-diameter sphere of cryogenic air ought to be orbitable by today’s larger rockets, even given the extra boost needed to be go westerly rather than easterly. After a few proof-of-concept flights, a few score or maybe hundreds of such temporary air bubbles could go a long way to reduce the cloud of debris and avoid a Kessler Syndrome disaster.
    I haven’t been able to find any study done of this idea. Thoughts?

    1. “expanded naturally in space to vastly greater volume” Yeah, to put it mildly.
      Even at -200C all the molecules in that bubble of air are going to be getting out Dodge at around 200 meters per second. In a few minutes that bit of space is going to be indistinguishable in density from what it was before you liberated all those chilly molecules. You’re not going to be catching anything with that ephemera.

  16. I think that every Nation that has Space Junk (ie all of them) must cooperate on an Internation level to reduce the space rubbish. I also wonder about all the micro satellite being launched as well.

    1. 195 Sovereign States According to the U.N., I suspect that less than 20% of that have launched anything into space.

      Should China or Russia deorbit defunct american (spy) satellites, and vice versa. Deorbiting junk by any other nation than the one that put it up, could actually start a war.

      The small low earth orbit cubesats with Terminator Tape could deorbit after 12 years, depending on their altitude.
      (ref: https://www.nasa.gov/smallsat-institute/sst-soa/passive-deorbit-systems )

      1. Surely there would not be that much of a problem if the Space nations all sat around a “round table” and discuss what can be removed.

        How many of the micro satellites are planned and are now in orbit? That could make thing difficult for Moon/Mars missions.

  17. Paul: thanks for the comment about plain air expanding so rapidly as to be useless. Indeed while it would be cryogenic at launch, in orbit on the sunny side of earth it would heat up much higher of course. Will have to ponder that problem.
    Several comments address the political issue of international non-co-operation. Even if a practical method is found, that would of course be as fraught as any of the other “tragedy of the commons” problems we humans have not solved. But without a practical operational method, there is no chance of success.

    1. The air doesn’t even need to see sun and heat up to skedaddle — even cryogenic, those molecules are still moving at 200 m/s, bumping into each other and their container. Put them in open space with nothing to constrain them: they’re gone, they aren’t hanging around.

      The issue of “the commons” in space or other bodies is very important: how we structure governance of those resources is going to affect the rest of our existence, and how we make it work out there will have repercussions on how we run our society here on Earth. An extremely interesting and timely TED talk on the topic: https://www.ted.com/talks/jessy_kate_schingler_civilization_on_the_moon_and_what_it_means_for_life_on_earth

      1. … Shooting lasers at things in an environment where a pea size object orbiting in the opposite direction you are can lead to a very bad day….yeah that sounds like a great idea.

        What’s wrong with cubesats that grapple a piece of space junk, then let out a long conductive teather which can be energized to push against the earths magnetic field fo deorbit objects? There could be a larger mothership with manuvering thusters to align various orbits before ejecting a cube sat to deal with the junk. Its not exactly quick, but you won’t be leaving tiny balls of death behind.

  18. A large rubber band between earth and the moon in some sort of Van de Graaff configuration “would” allow a massive static potential to be generated. This could either repel the debris or attract it to the atmosphere. It might also throw the atmosphere off into deep space. But let that risk not stand in the way of science.

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