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Jonathan Missel / Texas A&M
Sling-Sat is a space sweeper idea designed to remove orbital debris from Earth orbit.
By Leonard David
Space.com
A proposed space-junk removal system would hop from one piece of debris to the next without burning much fuel, potentially making a de-clutter mission economically feasible with current technology.
The TAMU Space Sweeper with Sling-Sat, or 4S for short, would harness the momentum imparted by capturing and ejecting one object to slingshot on to the next chunk of space junk, its developers say.
“The goal of this mission is to remove as many pieces of debris with the minimum amount of fuel,” said Daniele Mortari of Texas A&M University.
A growing problem
Earth is surrounded by a huge and ever-growing cloud of orbital debris — stuff like spent rocket bodies, dead spacecraft and the fragments generated when these objects collide. [The Expanding Danger of Space Junk (Video)]
NASA estimates that about 500,000 pieces bigger than a marble and 22,000 as large as a softball whiz around Earth at fantastic speeds. And there are probably hundreds of millions of flecks at least 1 millimeter in diameter.
This cloud of junk poses a threat to the satellites and spacecraft circling our planet, including the International Space Station, and many researchers say humanity must act soon to prevent the problem from really getting out of hand.
“It is well understood that we are past the point of no return. Relying solely on improved tracking and avoidance is not enough … it is simply a technical form of sticking your head in the sand and crossing your fingers,” Texas A&M Ph.D. student Jonathan Missel told Space.com. “We are at a point where the problem needs to be solved, with active removal, not just avoided.”
A new idea
Many ideas have been put forward over the years to combat the space-junk threat, including schemes that would blast debris with lasers or snare it in a giant net.
“While they are interesting to think about, they are often threatening to operating satellites, or need technological advances that are decades out,” Missel said of some of the more ambitious offerings.
The most technically and politically sound idea is a simple rendezvous mission, during which a clean-up craft would travel to and de-orbit debris objects one at a time, Missel said. But such a mission would burn loads of fuel to get between widely spaced targets, making it “fatally plagued by inefficiency,” he added.
The 4S system, which Missel and Mortari are developing, aims to correct this fatal flaw. It would snare debris at the end of a spinning satellite, then fling the object down to burn up in Earth's atmosphere.
The spacecraft would harness the momentum exchanged during both of these actions to cruise over to the next piece of space junk on its list, minimizing fuel use and extending its operational life to the point that such a mission might be practical.
Work on 4S this year includes looks at hardware options, Mortari said, and further optimization of the idea.
Leonard David has been reporting on the space industry for more than five decades. He is former director of research for the National Commission on Space and a past editor-in-chief of the National Space Society's Ad Astra and Space World magazines. He has written for Space.com since 1999. Follow Space.com on Twitter @Spacedotcom. We're also on Facebook and Google+.
- Photos: Space Debris Images & Cleanup Concepts
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Leave a Comment:
If we fling our space debris out of orbit and it finds an orbit of another planet with intellegent life, will that prompt a visit from the above said aliens? They will probably bring a sign that says "Do not litter, we found your flung space junk."
So DAMN typical - "just toss it out the window" and let someone else clean it up. For all our history we have NOT learned a single thing I'm pretty sure.
Perhaps you could read the story before commenting? Both of you?
This sounds pretty complicated, figuring out the exact reaction to "Catching" something without knowing the exact mass.
Sqrly,
I did get a laugh out of Hope's reply though, didn't you?
Just in case you missed it, the article clearly states:
"The 4S system, which Missel and Mortari are developing, aims to correct this fatal flaw. It would snare debris at the end of a spinning satellite, then fling the object down to burn up in Earth's atmosphere."
Unless I am completely misunderstanding the English language (always possible), the 4S mission would throw the junk back at EARTH, to burn up in Earth's atmosphere, rather than out of orbit to pollute elsewhere.
personally, I love it when my wife flings my junk
I am going to try to comment on this with a straight face-
It would be like if you were at a traffic light and you noticed someone tossing a wrapper out their window. Being the good Samaritan that you are, you pick up the wrapper and followed them to the next traffic light and then threw the wrapper back into their car and say, "HEY, @!$%#O! YOU DROPPED THIS!" and then continue to pummel them into submission until they bow to your whim as you subjugate them into slavery and use them for anal probing expirements while you strip the oceans of water leaving the salt behind as waste. Meanwhile with the lack of water on the planet, the weather patterns change and the food chain for the countless animals start to breakdown causing catacalysmic catastrophes that the annals of time cannot fathom...
All because you threw a wrapper out of your window.
;-)
That's,
Thank you, finally, someone with a sense of humor! LOL
Inspired,
Thank you as well! Finally some humor!
It's fine. Gordon Freeman will save us!
This space junk cleaner, would not burn loads of fuel if it had a nuclear power source. In fact it could stay up there, cleaning up for years, and never run out of fuel. The rover curiosity has a proven nuclear power pack that could do the job. Whatever they decide to use should will have to be protected from a impact while doing it's job.
did they give a duration of this satellite?
I could be wrong, but as I understand it, while the power source of a orbiting spacecraft (nuclear, solar, etc) keeps the "lights on" for its instruments and devices, it does NOT produce any thrust. The movement part of the equation is still left to solid or liquid fuels to power the thrusters and fly the spacecraft through space. Curiosity, being on the surface of Mars, needs no thrusters and can drive over land using its power source to drive the wheels.
People always have problems with allowing nuclear material into orbit. For obvious reasons.
But Harcourt hit the nail on the head. Most use nuclear fuel as a power source to produce electricity. As far as I know the thrusters for this satellite would use some kind of liquid fuel. Even in NERVA rocket design they use (usually) liquid hydrogen (if I'm not mistaken) as the fuel.
So, if you can provide power with solar cells and get some momentum without putting nuclear material into orbit, then why risk putting potentially dangerous material in orbit... especially when you're stated mission objective is to clean up orbital space.
Whatever they decide to use will have to be protected from an impact when it enters into the area of junk while doing it's job, as it could be damaged and become a piece of space junk.
That would be ironic if the dejunker satellite itself got
whacked by space junk, but this idea sounds feasible to me. There likely would
be myriad choices of downward directions the satellite could throw its prey,
thereby zinging it off to its next target. I think this idea is weird enough to
actually work, and economically so, because it largely mitigates the otherwise
huge fuel issue. I like it and sincerely hope the idea pans out.
Well, given its intended function, they could make the thing pretty sturdy, couldn't they? This isn't like most satellites that have to maintain a great deal of sensitive equipment and electronics. Given that it's pretty much designed to smash into other satellites, it would have to be a basic design feature.
Fling it where????
down
Well, strictly speaking, "down" isn't a direction in space, but yeah.
It would be flung back at the Earth. Good old air friction does the rest.
On a more serious note, I wonder if any of it is too big to burn up when it comes back into our atmosphere. What do they propose to do with this space junk? I don't think the article said.
It would have to be a pretty massive sat to survive re-entry.
Our vehicles have to be specially designed and shielded to survive atmospheric re-entry, or they would be burned to cinders before they reached the ground. Satellites tend to be much smaller and more delicate, never having been designed to survive that kind of stress and heat, so I would easily wager that we've never built a satellite (unless you count the ISS) that could survive re-entry to the point of causing damage on impact.
I believe the only orbiting objects that are/were capable of surviving re-entry on a large scale were space stations (Skylab, Mir, etc). I don't recall ever reading that boosters could/would survive. Pieces of some of the larger satellites might, but that is a calculation for NASA/ESA/JAXA/other space program and the company doing the de-orbit to work out.
OK then, only really big stuf like the ISS wouldn't burn up. Got it.
Everything comes with a cost. Perhaps if they factor it into the design of these boosters to have a small amount of propellant and a thruster that would fire whenever the nozzle was oriented to nudge the booster towards earth. Little by little the boosters would slower deorbit. The same type of packages could be mated to these old pieces of space junk still orbiting. Since all these piece of debris are cataloged I am led to believe the ephemeris data should be good to go for at least a week if not longer. Knowing the orbitology of the debris would allow folks at NASA and NORAD to play traffic cop and nudge each piece down strategically and deliberately so they all reenter over the South Pacific.
Or outsource it to contractors that can do the service for a fee. Boom- ANOTHER space industry business model is created!
(And I get 2% of the gross revenue as part of my finder's fee.)
;-)
Lack of comprehension, if sent toward deorbit burn then momentum sends the sat higher and earth's atmosphere will do the work. We wouldn't send junk toward escape velocity, not realistic even with an ion drive.
Surprisingly elegant solution.
Throw it into the atmosphere to burn up and use the energy gained to move in the opposite direction.
It would take some serious software, but conceptually so simple it should have been thought of years ago.
The big problem I see is that the entire path has to be perfectly choreographed. Once you miss one piece, then your entire trajectory & mission is thrown out of whack and without lots of fuel to self correct, you're done. And with changing fuel levels comes changing mass properties With exact knowledge of all the masses & velocities, the math will work, but remember what Jurassic Park said about Chaos Theory!
BTW - nuclear fuel cells are great for producing electricity on rovers & deep space satellites, but I don't think they are any good for propulsion in space ... yet.
You still need a fuel source, but you don't need as much...
exactly who is going to pay for these "Space Roombas"? Since the debris is the work of several countries how do we track who is responsible and bill them accordingly?
Just like a professional in other fields, I imagine the company in question will track the "billable hours" to reach, deorbit and move on from each satellite, then bill the appropriate nation accordingly. It actually doesn't sound too hard to track; calculating the price (including launch and other costs) and getting each nation to pay may well be another story.
That would only work for larger space debris, such as satellites. Smaller items like nuts and clamps would be fairly difficult if not impossible to track to the source. And what about disputes? Say satellite from country A runs into satellite from country B. Who pays? Its not like auto insurance.
I get the distinct impression, given that all the people involved in/commenting on this project seem to be from either NASA or American organizations, that this is more of a "screw it, let the Americans handle it" sort of project. The government (IE, tax base) will probably be footing the bill, so it's nice that they're coming up with an efficient, relatively low-cost method of doing it.
Whoever cleans up orbital space will pay for it. There will be no active "billable hours". There may be at some point a treaty or contract in which money changes hands, but that is still highly unlikely unless/until after the mess is cleaned up to a larger degree.
The reward for cleaning up orbital space is the end result itself: having a cleaner orbital space. NASA will take on this burden simply to so they can maintain some amount of safety during space launches they are involved in.
If nobody does anything then there will be a point at which no one can launch even a modest satellite into space without fear of a space debris impact. That is the main focus of the "beyond the point of no return" statement. We have effectively buried ourselves in orbital debris. Right now it's okay, but as more and more pieces collide there will be more and more space debris that causes a bigger and bigger problem. It's only getting worse and it will take a very long time for Earth to clean up the problem itself... and that's assuming we stop launching stuff into orbit, which we won't.
The only safe direction to 'fling' space debris is down toward earth and let it burn up on reentry. If you 'fling' it outwards, it could take up an elliptical orbit and remain a danger to other spacecraft or satellites.
If they caught a piece a day it would take over 1300 years to catch all the marble size pieces. Also, they wouldnt have to throw it down. Just SLOW it down under escape velocity. Gravity would do the rest.
gravity already has a hold of these items of debris. The problem is we can not wait for our planet's gravity to do the work. The debris will continue to smash into other debris creating still more pieces of debris and the debris field will get worse. That is why we are "beyond the point of no return". We need to clean it up now and as soon as possible to have any hope of maintaining any semblance of safety during space launches.
I'm pretty sure they could manage more than a piece a day. And really, we don't need to clean it up so much as we need to just start removing debris at the same rate that we shoot it up there, in order to keep it from becoming a serious problem.
I wonder if there are any dead alien bodies floating around that junk that we're not being told about.
Good plot for a Sci Fi movie.
Original to say the least!
It'd be a better plot for a sci-fi movie if the floating alien bodies weren't dead but in some kind of hibernation.
I suppose if they were dead you could make it a cosmic who-done-it.
Nah, Mob_barley; that one has been done before. Remember the movie, LifeForce? CLASSIC! And it helps to have a drop dead actress walking around nude in almost every scene...
;-)
And also in David Brin's newest book "Existence"
http://www.davidbrin.com/existence.html
(David is an astronomer, and a friend, so I may be a wee bit biased when I say that HIS BOOKS ROCK!)
i love brin's books! "startide rising" and its sequels are golden!
Very ingenious, but as it stands now the concept is too crude. An improvement would use onboard lasers to vaporize the material as an efficient means of propulsion to the next piece of orbital debris. That said, the concept which I favor is a counter orbital solar powered laser system which retros debris from orbit by vaporizing a thin layer of material on the forward surface of the rogue debris. Most debris in orbit has been launched in one direction around the Earth designed to make maximum use of the Earth's rotational energy to achieve orbit. Launching a high powered laser in the opposite direction around the Earth would potentially enable us to retro this debris out of orbit by vaporizing a small amount of this orbital debris on the forward surface of the rogue object. Minimal orbital maneuvering would be required to do this, and this approach allows us to be selective to a maximum degree when it comes to targeting this orbital debris. - Rick Carter
Wouldn't doing it that way increase the fuel required and also increase the debris' relative speed with regard to your laser system?
The debris is going one way, and you want to launch something the other way, and then fire laser's at everything... and trust the laser button to which nation??
Although the proposed solution is certainly "crude" compared to a giant space laser, I fail to see how it's any less effective than your proposition, and it's considerably cheaper.
And this is coming from someone who is very much a fan of space lasers.
Presumably this would be an international collaborative effort, so the international community would oversee the operation of this orbital laser, even if the laser technology was classified. The solar powered laser beam travels to each of the targets in place of the spacecraft, so it is much more efficient. - RC
PS - Ideally you would actually have several of these counter orbital lasers systems at different orbital altitudes, which would reduce any fuel requirements even further. - RC
((I already know humanity is going to reject anything I try to say to them, regardless of what it is. I am very used to it by now, I just want my conscience clear by sharing these things, so none of the blame falls on me on the "flip side" for whatever goes wrong in this world.)) - RC
PS - You all can keep your "End Time" religions just as they are, too! I won't interfere anymore. Have fun, everyone, and good luck with your future global totalitarian theocratic kingdom perpetually ruled by a supreme demigod dictator! It's not my idea of a New World Order, but I will keep all that to myself from here on out. - RC
The world's governments are trying to avoid paying the bill for orbital cleanup. I think a fair compromise would be to enact some kind of space treaty among all space-faring nations so that each country would pay into an account an amount of money that is directly correlated to the amount of satellites and other objects that country has launched. China and the U.S.A. should have to pay more for each of the satellites they have blown up.
Also, part of that treaty should be an obligation for all space-faring nations to institute a de-orbiting strategy for all future satellite missions. There needs to be a plan in place to deorbit everything that is put into orbit.
And I can tell already that there would be disagreement as to how the "treaty monies" are spent so there should also be a committee space industry specialists from each interested party to convene and decide how best to implement the space clean up plans.
It's in all space-faring nations best interests to clean up orbital space. And all space-faring nations should foot the bill to clean up orbital space. But that bill should be representative of each countries activities in said orbital space. And the clean up effort should also be indicative of each nations capabilities to participate.
That's a perfectly fair, reasonable solution that would minimize costs and advance the cause of responsible and sustainable space conduct as a global project rather than the accomplishment of national interest, and possibly lay the groundwork for unprecedented international cooperation on conduct while reaching out from our planet.
It'll never happen.
Touche. Well played sir.
Rubish, space junk will have rotation moments, grasping on to them will impart a comons rotation moment that will require fuel to stabilize. Just puff the junk with air or thrusters, prefrably in a counter direction orbit.
That's the problem. To "puff" requires some substance with which to puff. There goes your efficiency.
You're better off finding a good way to use the rotation moment. If it destabilizes the craft then let it destabilize the craft. Use it rather than shy away from it.