Aerospace engineer proposes arm-equipped satellite to affix propellant kits to space junk to send it back home

August 12, 2011 by Bob Yirka, report
Image: NASA

( -- Over the past several years, many scientists and armchair enthusiasts alike have offered up a possible solution to the ever growing cloud of space junk circling the Earth; the result of leftover missions, collisions and inadvertent accidents.

One such proposal even suggested a cloud of tungsten be sent up to coat the trash, causing it to grow heavy enough to fall to Earth.

Now, a more practical approach is being offered by Italian aerospace engineer Marco Castronuovo of the Agenzia Spaziale Italiana. In his paper, published in the journal Acta Astronautica he suggests that a satellite carrying among other things a that could be affixed to a large piece of space junk, be launched. The satellite would have two robotic arms he says; one to grab hold of the piece of junk (say a spent rocket part) the other to affix the propellant device that once activated, would guide the piece of junk towards Earth, where it would burn up (hopefully) in the atmosphere.

Space junk is of growing concern to those who launch satellites and of course manned craft into space. Just last month evasive maneuvers had to be conducted to prevent the from colliding with an object in its path. And while the amount already up there is of concern, what is even more troubling is the possibility of space and the debris up there falling prey to the Kessler Syndrome, a condition whereby pieces of collide with one another, causing them to break into several smaller pieces. Those smaller pieces, because there would then be more of them would then have a greater chance of colliding with something else, thereby creating ever smaller pieces and on and on, until the number of minuscule pieces would total in the tens if not hundreds of millions of pieces, eventually creating such an inhospitable environment that functioning couldn’t hope to survive.

Castronuovo says such a satellite as he proposes, would be capable of de-orbiting 35 large objects over a 7 year period, which would be more practical than it sounds because it would target the forty-one large rocket bodies that are currently orbiting in the sun-synchronous orbital region near the Earth, which he says is where most of the catastrophic collisions in the near term are likely to occur.

Explore further: NASA proposes laser use to move space junk

More information: Active space debris removal -- A preliminary mission analysis and design, Acta Astronautica, Article in Press. doi:10.1016/j.actaastro.2011.04.017

The active removal of five to ten large objects per year from the low Earth orbit (LEO) region is the only way to prevent the debris collisions from cascading. Among the three orbital regions near the Earth where most catastrophic collisions are predicted to occur, the one corresponding to a sun-synchronous condition is considered the most relevant. Forty-one large rocket bodies orbiting in this belt have been identified as the priority targets for removal. As part of a more comprehensive system engineering solution, a space mission dedicated to the de-orbiting of five rocket bodies per year from this orbital regime has been designed. The selected concept of operations envisages the launch of a satellite carrying a number of de-orbiting devices, such as solid propellant kits. The satellite performs a rendezvous with an identified object and mates with it by means of a robotic arm. A de-orbiting device is attached to the object by means of a second robotic arm, the object is released and the device is activated. The spacecraft travels then to the next target. The present paper shows that an active debris removal mission capable of de-orbiting 35 large objects in 7 years is technically feasible, and the resulting propellant mass budget is compatible with many existing platforms.

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Adam WL
3 / 5 (3) Aug 12, 2011
The reason this idea is impractical is because you must burn thrusters to transfer orbits. Open litterature by others towards the design of this type of space vehicle has shown that you could only carry enough thruster fuel to transfer orbits up to about 6 times. Your garbage collection ratio is so bad for each vehicle you would have to put into orbit that it is impractical.
5 / 5 (3) Aug 12, 2011
Read the article. Only targeting 41 large rocket bodies.
would be more practical than it sounds
4.4 / 5 (7) Aug 12, 2011
How about if you use solar energy to compress a really huge spring. You can use and reuse the spring, each time attaching to a new piece of junk and springing it towards earth - renewing the orbit of the debris collector and collapsing the orbit of the junk.

I know it's probably a dumb idea... but why?
not rated yet Aug 12, 2011

Very interesting idea... I laughed a bit when I imagined the really huge spring in space throwing the debris back to Mother Earth, but hey.. A lot of ideas that people laughed at originally, finally became alive and made their inventor famous.

Keep up with the creativity.
1 / 5 (3) Aug 12, 2011
I'm curious how this plan compares in price and feasibility to a much smaller single rocket for each target?

And it'd be nice if they would reconsider the orbiting laser idea.
1 / 5 (2) Aug 12, 2011
Star Technology and Reaearch has another interesting proposal that has been space-tested. See the EDDE brochure and ppt simulation at
2 / 5 (4) Aug 12, 2011
Why send them back when the energy for launching them is already spent. I would suggest solar-ion powered satellites for collection. Why spend more money to bring these objects down only to spend more relaunching it. A set of satellites could be recharged with propellant (you need ions even with solar power)at a base unit or "launched custom care packages." Automation mates with previous knowledge and a small ground team monitoring everything. Then NASA can learn recycling and real industry concepts with all sorts of financial possibilities. Come on people, we aren't just talking about recycling metal but also ridiculous fuel amounts? anyone worried about asteroids or other non-earth objects should realize the slimmer chance of impact bunched together. most debris would go to earth or above orbital velocity upon collision. There should be a continuous recycling program in use if we plan to live there eventually. Space foam sounds cool to keep things together...
2.6 / 5 (5) Aug 12, 2011
I think it would be very nice to gather up all the space junk and build something with it, or break it down into useful materials. It costs so much to send things into space, we should try to use this junk somehow! If we can perfect nanobots or some other technology that can break down the junk into its respective elements, then rebuild it into a space station. It might take more energy to send the junk rocketing towards Earth than it would to break it down into something useful.

Space junk is one of those problems that is ahead of our time. I do like that they are tracking and targeting the big chunks first.
1 / 5 (3) Aug 12, 2011
I love this spring idea. How hard could it be to compute the best angle to achieve the two goals of: a) causing the debris to re-enter the atmosphere, and b) altering the satellite's orbit so as to intersect the orbit of another piece of junk? Imagine fifty or so of these things clobbering a couple hundred pieces of junk a year.... but what "spring" would one use -- it might not be coils of wire but it'll have the same effect.
5 / 5 (1) Aug 12, 2011
@krundoloss. I love your idea! With it currently costing thousands to tens of thousands of dollars to send a single kg into orbit, imagine the valuable resource which is already up there! each of those rockets are worth millions of dollars in spare parts and materials. Especially when we start to construct our spacecrafts in space rather than the earth, this material will indeed be a boon.
3 / 5 (3) Aug 12, 2011
The spring idea won't work well because the satellite would be thrown backwards with the same total momentum (but opposite direction) as the junk. You would need thrusters to return the satellite to its previous orbit every time you fired the spring. Unless the mass of the satellite was much larger than the mass of the junk - then the satellite's recoil would be minimal (but still needs to be corrected).
2 / 5 (4) Aug 12, 2011
"..the satellite would be thrown backwards with the same total momentum (but opposite direction) as the junk.."

How hard could it be to compute the best angle to achieve the two goals of: a) causing the debris to re-enter the atmosphere, and b) altering the satellite's orbit so as to intersect the orbit of another piece of junk?
not rated yet Aug 12, 2011
Ya, don't discount the electrostatic ram (spring repel) idea. You could also do a rail gun in reverse (action reaction) w/depleted uranium slugs at ultra high speed. You want to do the "spring" repel at objects in lower orbit to kick ya up into higher orbit and hit those objects. Remember that you just need to knock the object into a eccentric enough orbit to have the atmosphere drags it down, not knock it out of the sky. Gotta copy of Fundamentals of Astrodynamics by Bate/Mueller/White circa '71 if anyone wants to do the math.
not rated yet Aug 12, 2011
Why not some sort of very large net strung between two large, heavy satellites that make slow orbits starting at north pole to south?

Once the net hits a certain quota, close it up, drop it back to earth, or simply leave it in orbit for a second group to pick up.
not rated yet Aug 12, 2011
Key here is delta V. If you use some device on the spacecraft to propel the junk anywhere, you are implying the same delta V (in reverse) being applied to the spacecraft. Springs, rail guns, whatever. The amount of delta-v needed to make a realistic orbital change to a massive piece of gun from a much smaller spacecraft is large, and the spacecraft will go shooting off in the opposite direction at a really high rate of speed. Really high.
not rated yet Aug 12, 2011
How about attaching solar sails and telemetry units to junk? Then they could be guided into known positions... e.g collected into a "scrapyard".
3 / 5 (1) Aug 12, 2011
Anyone know how many Kgs of junk is up there?

What if we retarded/accelerated the orbits of some pieces relative to others so that all of it ended up near each other?

Then, weld, glue, truss, it all together.

Mount some sort of rail gun ( solar recharged? ) to the heap.

Use the mass of the scrapheap as a launching pad for smaller payloads further into space, not down to earth.

Make the components of the heap accessible, just in case they can be put to a better use later on then serving as cosmic ballast.
1 / 5 (1) Aug 12, 2011
A real trick with the proposal would be to attach the booster so that it pushes exactly against the piece of junk's center of mass. If the booster winds up off-center, then rather than pushing the junk anywhere it'll spin it up like some Catherine wheel firework. Or otherwise, to prevent this from occurring, the booster would have to be quite sophisticated, large, and heavy (and therefore expensive), with either gyroscopic stabilization or attitude control engines plus inertial or optical guidance system to make sure it follows the prescribed trajectory...
not rated yet Aug 13, 2011
how about a empty booster as a flying trash can?match speeds and let the trash float inside,move to the next bits and so on until the "can is full and return it in a blaze of junk.i would think you could launch a empty casing of some sort with radar and video links and the weight saved by not having a payload would used for fuel for "driving" the trash can around.the end could always stay open as the junk and the can are moving at the same speed.some clever arrangement of "nets"
"spiderwebs" "flypaper" could be used to secure trapped junk.
i recall my Dad watching a sci-fi TV program back in the 50's about space ships using huge funnel shaped ships to trap
asteroids for mining.he was really put off because a guy tried to catch one that was to big" in real like nobody would do something stupid like that!!" sound in space.
1 / 5 (1) Aug 13, 2011
I agree with an comment made above. Just bounce them 'down'. Given enough mass, many smaller pieces of junk could be de-orbited while help maintain the orbit of the 'bouncer'.
not rated yet Aug 13, 2011
What about a manueverable platform with a parabolic reflector or fresnel lens and a trap for debris ? Could they capture and vaporise debris in space using something like ZPM to maintain position relative to the Sun ?
not rated yet Aug 13, 2011
Can't we just teleport it to the junk-yard?
Wait, 2011 right?! I keep forgetting that.
1 / 5 (4) Aug 13, 2011
This article reminds me a fly killer I saw on a 70s TV show. It was 2 small blocks of wood. You place the fly between the blocks and squish it.
not rated yet Aug 15, 2011
How about modifying the ISS into a space garbage truck when we've finished with it (2020?).

It's a bit simplistic but it could be used to collect up as much as possible and then burn the whole thing up in the atmosphere or crash it into the sea and recycle as much as possible?
5 / 5 (1) Aug 21, 2011
if they are gonna send it in any direction maybe its best to give it a nudge in the direction of the moon. it all cost big bucks to get that far so why just burn it up. we will definitely be using metal on the moon soon enough so hey, job halve done.

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