Space junk poses an ever-growing threat to the satellites that help the military and the IC communicate and gather intelligence, and also the ones that serve your obsession with GPS, Sirius radio, Google Earth, and Netflix. As of 2013, NASA estimated there are 500,000 pieces of space debris between 1 and 10 cm in diameter; some 21,000 pieces of which are larger than 10 cm. Unfortunately, NASA also estimates that there are more than 100 million pieces of debris smaller than 1 cm that cannot be seen; U.S. space tracking facilities can only routinely see pieces of a certain size. In the heavily-used Low Earth Orbits (LEO), the lower limit of what we can track is about the size of a softball; in Geosynchronous Orbit (GEO), where most large telecommunications orbit, it’s about the size of about a basketball. The Kessler Syndrome
We’ve already reached the point where the growth of debris in LEO has become self-sustaining. Human access to space might eventually become impossible. This is called the Kessler Syndrome. Back in 1978, NASA scientist Donald Kessler proposed that one day there would be so many objects in low Earth orbit (LEO) that a few collisions could cause a runaway cascade, with each collision creating yet more debris that would go on to cause more collisions, creating more debris… and so on, eventually rendering space travel and exploration impossible. “The Kessler Syndrome is a mathematical singularity,” says Darren McKnight, a member of a recent National Academies panel on NASA’s meteoroid and orbital debris program. “Based on the equations, we’ve already passed the critical density.” How does it affect the IC? The immediate concern for the IC is the loss of one or more of satellites, which would limit our ability to communicate globally and/or limit our ability to collect intelligence. This risk has an interesting detail: If one of our satellites were to go dark, we wouldn’t necessarily be able to tell whether that was due to a hostile action or a random collision with space junk. We could suffer multiple attacks against our satellites before even realizing we were under attack. Given that most space-faring countries do not have the ability to track space debris—the U.S. has the most sophisticated capabilities, followed by the Russians and to a lesser extent the EU— it is highly conceivable that, in a time of crisis, if there were a collision between a piece of debris and a working satellite and the satellite went belly up, then the owner government of the satellite might conclude that it was a deliberate act. A more abstract impact for the IC is the advance of the commercial sector into space and the growing need to treat space as a topic for dedicated collection and analysis. Arms race in space Orbital debris has reached its current disastrous status largely because during the last decade and arms race has played out in orbit between factions in the US and Chinese militaries. John Arquilla, a Pentagon consultant and professor at the US Naval Postgraduate School reports, “Almost every Air Force general I talk to says, ‘We’re going into space.’ For them, that really is the ultimate high ground, and they’re bedazzled by the technology—concepts like Rods from God and bombers that rise into orbit then drop directly down on a country with no overflight requirements. Unfortunately, an arms race in space will only create a catastrophe for everybody, including themselves. The simple fact of the matter is that you can destroy or cripple things in orbit far more easily than put them up there.” The Chinese proved this handily with their 2007 ASAT test. In one shot, they fragmented one of their own 750-kilogram satellites, creating a 20-percent increase in total debris. Not to be outdone, the US Air Force demonstrated its superior ASAT prowess a year later by knocking down a failing American satellite surgically, showing it might in theory destroy Chinese space assets without generating so much debris that its own hardware would be threatened. In practice, this capability would be irrelevant if a conflict reached the point where both sides took potshots at each other’s satellites—the Chinese could simply try to destroy as many satellites and create as much debris as they chose. It’s hard to see the Air Force’s strategic thinking here as more than a carryover from MAD-based nuclear deterrence doctrine. Both sides’ behavior, moreover, is especially regrettable because orbital debris growth was previously slowing. As McKnight laments: “We were doing a lot of good stuff and it was ruined in an instant.” We wouldn’t be facing a Kessler event in 2014 if international policy and governance had reigned in US and Chinese militaries. No technological fix, however brilliant, will matter much without international agreements that prevent the creation of debris, and IC is responsible for advising the policymakers. What’s been done on the technology front? There are three elements to addressing orbital debris: Tracking what’s already up there, removing as much as we can, and not adding new debris. Tracking Tracking of space debris has evolved from crude catalogs and databases into sophisticated models run with powerful simulation software. But even the best models need good data or sensor tracks. A case in point is the calculation set made by CelesTrak orbital element software, from Analytical Graphics Inc. (AGI), which indicated that a functioning US Iridium satellite and a dead Russian Cosmos satellite would miss by at least 584 meters rather than become the first accidental hypervelocity collision as they did in 2008. AGI’s flagship product, the Satellite Tool Kit, is used worldwide in over 40,000 installations by aerospace, defense, and intelligence professionals. Radar and optical detectors such as lidar are the main tools used for tracking space debris. NASA Orbital Debris Observatory tracks space debris using a 3m liquid mirror transit telescope. Radio waves have been used to track space debris. Other sources of knowledge on the actual space debris environment include measurement campaigns by the ESA Space Debris Telescope . President Obama has indicated the US will work with the Indian space agency on tracking and locating debris in orbit, and until last year, the Pentagon used what was called a “Space Fence” to track the junk and warn of potential collisions that make owners scramble to move their satellites out of the way. Removal Many of the options for removal are “dual-use technologies” – they could destroy a satellite as easily as destroying a piece of debris – and thus restricted under international agreements. Potential solutions include things like electrodynamic tethers, nanosatellites, solar sails, space grapples, and tugs. Some of these technologies even exist as more than prototypes, although they’re sequestered away under military control. Speaking of which, I have some suspicions about the X-37B. In late February, Japan’s space agency (JAXA) launched a space trawler, a spacecraft that dragged a giant aluminum and steel net while orbiting Earth, hoping to bag itself some space junk. The Japanese have woven three wires into a net-style electrodynamic tether to beat the initial structural stresses, like friction, that are inherent in uncoiling a very long wire. The net design also limits the likelihood of a single-stranded tether becoming severed by a debris particle a probability that’ll grow as orbital debris increases. NASA has toyed with the idea of a “laser broom,” an Earth-based laser that fires up into space, shifting debris that’s on a collision course, or possibly de-orbiting it. This laser could destroy small pieces and slow large pieces, basically real-life Asteroids. Does another technology besides the laser broom look versatile enough to handle both the small-scaled debris and the big-mass items? At present, not really. For now, the likeliest options for small debris removal are some form of “collection media,” such as aerogel, which NASA already uses to catch comet dust. However, cost estimates for an aerogel solution come in at about one trillion dollars. Another option is a spacecraft that attaches a small rocket onto the debris, allowing it to guide itself into a safer orbit, or de-orbit in the atmosphere. DARPA’s Phoenix project wants to take small satellites up into space and attach them to old, inactive satellites — the small satellites would use the old satellite’s antennae array, reducing the amount of waste (but not the amount of junk floating around in space). Spaceballs currently being tested on the ISS are another part of the Phoenix Project. Nanosatellites are another approach to debris removal. Defined as microsatellites sized 1 to 5kg, these are a rapidly expanding market. Orbital debris removal is now one task for which such satellites are being designed. Representative projects here include the CleanSpace initiative at the Swiss Space Center, which is developing nanosatellites that will extend gripping devices to fasten to their targets; and the CubeSail nanosatellites which will release 5m x 5m solar sails made of mirrored membranes in LEO so they can then de-orbit objects of up to 500kg (~1100 lbs) mass. What Other Solutions Could We Explore? Theresa Hitchens is the director of the UN Institute for Disarmament Research and was previously the director of the Center for Defense Information in Washington, D.C., leading its Space Security Project. She says the problem is that we haven’t even got a decent legal definition of “space,” let alone a plan for dealing with dangers from beyond the boundaries of our atmosphere.
The primary obstacle is that the Outer Space Treaty of 1967 declares that all space objects, including non-functioning satellites and debris, belong to the country of launch. So a would-be Space Garbage Collector would need the permission of the launching country to remove or otherwise interfere with any given piece of space debris. To further complicate matters, most space debris is small and old, and it can be quite difficult to classify it as belonging to any one former space craft or launcher.
With the explosion of commercial and international space companies, determining country of ownership is more difficult than it was during the Cold War. The third draft of an International Code of Conduct for responsible spacefaring nations was released last year by the European Union. It moves usefully toward managing space traffic and debris. And for the first time, Beijing and Moscow have endorsed an official code of conduct in principle, so that’s new ground. Policy might need to copy the Law of the Sea and allow salvage rights. Or, as some economists suggest, we should begin taxing access to space. Peter J. Alexander, an economist at the Federal Communications Commission argues that orbital debris is just a standard “tragedy of the commons” problem. Space is a precious commodity, and people tend to overuse it, since users don’t pay the full price for the mess created by satellites. Similarly, no one country has the incentive to clean up the entire mess all by itself. Economists typically solve this problem with what’s known as a Pigouvian tax or user fee to better align those incentives. So, they ask, why not place a user fee on orbital launches to help pay for clean-up? That tax will slow commercial space programs, which would be bad for technology progress but good for national security as we wouldn’t have to deal with anyone and everyone having access to space. The private sector isn’t going to leapfrog governments in space debris removal anyway. Commercial space operators will resist spending any money on top of expenses that presently begin with launch costs of approximately $5,000 for each kilogram placed in LEO. As Nassim Taleb stressed in his book, The Black Swan, a black swan event only has to be so rare or unpredictable that most people ignore its possibility—and the precise timing of the next serious debris-creating collision is inherently unpredictable. So right now the most likely prognosis is that research into orbital debris removal technologies will get funded, but no serious deployment of those technologies will take place before the next catastrophic event occurs. Which most folks think will be in the 2015-2018 time frame.