Each dot represents a bit of known space junk that's at least 4 inches (10 cm) in low-Earth orbit, where the space station and shuttles roam. In total, some 19,000 manmade objects this size or bigger orbit Earth as of July 2009; most are in low-Earth orbit. Countless smaller objects are also circling the planet.
Credit: NASA/Orbital Debris Program Office.
Outer space has become Earth?s largest junkyard.
It is an international dumping ground for derelict spacecraft, wreckage from colliding satellites, remains from mischievous anti-satellite testing, spent rocket stages, discarded lens caps and clamp bands, paint chips and, yes, at one point, even a lost-to-space tool bag.
All that riff-raff might be out of sight, but it is far from being out of mind. This week, experts from around the world are attending a wake-up call type of meeting.
NASA and the Defense Advanced Research Projects Agency (DARPA) have teamed up to take a hard look at the issues and challenges of de-cluttering space of human-made orbital debris. The result: A first-of-its-kind International Conference on Orbital Debris Removal is being held today through Dec. 10 in Chantilly, Va.
Wanted: innovative solutions
Understanding the space debris problem is one thing. Hammering out viable operational concepts to eliminate the rubbish is another. Then toss in legal and economic issues, as well as incentives. And for good measure add to the brew international policy and cooperation requirements.
For many years NASA has considered means to ?remediate? the near-Earth space environment, that is, removing human-made flotsam from Earth orbit ? at both low and high altitudes, said Nicholas Johnson, chief scientist of NASA?s Orbital Debris Program Office at Johnson Space Center in Houston, Texas.
?We have also evaluated the feasibility of numerous concepts proposed by other U.S. government organizations, the aerospace industry, academia, and the general public,? Johnson told SPACE.com. ?To date, none of the techniques examined have proven entirely practical due to technical and/or economic reasons.?
Johnson said that, earlier this year NASA and DARPA ? which is renowned for its innovative solutions to exceptionally difficult problems ? agreed to host this week's international conference devoted solely to the subject of orbital debris removal.
More than 50 presentations from the United States, Russia, France, Germany, and Japan will be offered to address not only the technical and economic challenges, but also the legal and policy issues associated with orbital debris removal.
To promote the reliable operation of space systems in the near term, the removal of small orbital debris is of principal interest.
?To preserve the near-Earth space environment for the farther term, the removal of large debris?derelict spacecraft and launch vehicle stages, is required,? Johnson observed. ?Consequently, a variety of orbital debris removal techniques will likely be necessary to handle the entire spectrum of orbital debris sizes at all altitudes.?
Tragedy of the commons
Indeed, over the years various schemes have been aired to deal with the untidiness of orbital debris, be it huge aerogel-laden puff balls to snare debris, various types of galloping gotcha tethers, even vacuum cleaner-type contraptions.
?This is a tragedy of the commons kind of thing,? said Jerome Pearson, President of Star Technology and Research, Inc. in Mount Pleasant, S.C. ?No one country is responsible for cleaning up space.?
Pearson is a strong advocate for a roving space vehicle based on his work to fashion a propellant-less electrodynamic thruster system. This ElectroDynamic Debris Eliminator (EDDE) vehicle, he said, is the only viable method known for the plucking from space of large debris.
EDDE would be maneuverable, flying from place to place in low Earth orbit. This concept is reusable with each vehicle capable of removing many targets by simple debris capture, utilizing lightweight nets or a grappler.
Pearson, however, flags a knotty issue.
?You can?t just go up there and move somebody?s stuff without permission,? Pearson said. ?Anything that can go up and grab a piece of debris and bring it down?well, it can also grab somebody?s operational satellite and bring it down. That?s a space weapon,? he cautioned.
What?s needed is some kind of international agreement, Pearson said. ?There?s a lot to be done there. I think it may be more political?more diplomatic than technical,? he added.
Umbrella of technologies
One proposal to be aired at the conference is a revisit of Project Orion ? an idea that received a NASA technical look in the 1990s.
The scheme uses rapid-fire laser pulses to blow off a micro-thin surface layer of targeted debris. That tiny bit of blow-off acts as a miniature rocket motor. It?s enough oomph to tease the object?s perigee ? low point of its orbit ? to where the Earth?s atmospheric drag takes hold of the object, reentering the refuse to a fiery finale.?
The concept of orbital debris removal via laser ? whether by ground-based equipment, an airborne facility, or a space-based system ? has greatly advanced over the years, said Jonathan Campbell, a physicist at NASA?s Marshall Space Flight Center in Huntsville, Ala.
Campbell said that one of the principle findings from the earlier Project Orion appraisal that he managed was that ground-based laser removal was feasible and affordable in the context of spaceflight budgets. At a cost of only a couple of thousand dollars per object removed, this remains true, he added.?
Thanks to the continued progress in laser and associated sensor technologies, Campbell?s view is that the ground-based laser approach should be even more effective and affordable than in the 1990?s.
Campbell said that, while all technologies have their niche as partial solutions to the orbital debris problem, there?s a sizeable load of lethal objects in low Earth orbit. That being the case, he said, only laser technologies offer any hope of removing hundreds of thousands of objects economically in a reasonable timeframe.
?There are some 300,000 objects larger than one centimeter?and they are all moving at hyper-velocity. The only way to address this huge population is with laser technology,? Campbell noted. ?Orbital debris removal is a complex problem, one that will require an umbrella of technologies to do a complete solution,? he stated.
At this week?s meeting, space law specialist, James Dunstan, along with Bob Werb of the Space Frontier Foundation are set to call for an Orbital Debris Removal and Recycling Fund.
It?s the belief of Werb and Dunstan that the current legal regime creates perverse economic incentives that are greatly aggravating the problem of orbital debris. The quickest and surest path to resolving the problem, they contend, is to establish a legal and economic environment that places a high price on anyone generating new debris while simultaneously creating adequate rewards for anyone who mitigates debris.
?From the predictions I?ve seen of how the space debris population will grow in the coming years, it looks like the space community will need to take active measures soon to clean up at least some of the existing debris, or the problem could get away from us,? said Robert Hoyt, leader of Tethers Unlimited, Inc. of Bothell, Wash.
Hoyt is bringing to the DARPA/NASA event his notion tagged ?RUSTLER?, short for Round Up Space Trash Low Earth orbit Remediation. It too makes use of a propellant-less electrodynamic tether, he said, along with two other unconventional technologies to enable safe and cost-effective removal of defunct satellites, spent upper stages, and other debris from orbit.
?The question has always been who is going to pay to clean up the mess? Nobody really wants to get stuck with that bill,? Hoyt said. How you distribute the cost fairly among the many nations and commercial entities that utilize space is a tough conundrum to address, he admitted.
?It?s the communities that agree to share the cost of keeping their cities and environment clean that are able to prosper,? Hoyt suggested. ?The international space community is going to have to come to that same sort of agreement if it is going to prosper in the long term.?
An upshot of this week?s confab of gab by experts is bound to be what next?
For one, there?s likely to be a multiple-choice of technologies that appear worth further study. Actual in-space testing of debris removal ideas also seems to be in the cards. Also, what space debris targets are good candidates?
All this means money.
?The conference is what I consider a paradigm shift. We?re moving from defining the problem to looking for real solutions,? said Campbell.
Given this paradigm shift, Campbell said he was hopeful of seeing increased funding in this area as time goes along. ?There?s a need to turn this trend around in the growth of space debris. It?s going to take some time to do it. But we seem to be heading in the right direction now,? he concluded.
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Leonard David has been reporting on the space industry for more than five decades. He is past editor-in-chief of the National Space Society's Ad Astra and Space World magazines and has written for SPACE.com since 1999.