Space junk is getting worse. Could the answer be smart plastic wrap?
That concept, being investigated by Aerospace Corp. of El Segundo, involves blasting thousands of tiny, flat spacecraft into orbit. There they would find and hug the bits and pieces of failed satellites and rockets, dragging them into the atmosphere to burn up.
There are more than 7,000 metric tons of material in the near-Earth space environment, said J.C. Liou, NASA chief scientist for orbital debris. It can slam into a operating satellite or spacecraft at about six miles per second — faster than a speeding bullet — which means that even debris the size of a sand grain could prove catastrophic.
That was demonstrated in 2009, when an operational Iridium satellite collided with an inactive Russian satellite, creating more than 2,000 large pieces of orbital debris and many smaller pieces.
The problem is growing as more nations and private companies get into the launch business. And it has spurred a number of creative solutions, including a giant net that would scoop up space junk and setting off a bomb to knock it out of orbit.
Most haven't gotten past the development stage for a simple reason: no one wants to pay for them.
A Rand study on orbital debris published in 2010 found that although the space community agreed that space junk posed a risk, the lack of government and private industry funding to remove it suggested the "perception of risk" had not yet crossed a "critical threshold that would prompt demands for remediation."
In other words, it's going to take some expensive space disasters to make it worth investing in a fix.
Although NASA has funded some smaller technology development projects, it has yet to support demonstrations or operational missions, said Bill Ostrove, aerospace and defense analyst at market research firm Forecast International.
"It doesn't really neatly fall under one particular organization's jurisdiction," he said. "It's almost like a hot potato problem."
The technological challenges are daunting enough.
Aaron Ridley, professor of space physics at the University of Michigan, encountered this in 2010 during his collaboration with Raytheon BBN Technologies on a NASA grant.
The idea at the time was to fly a high-altitude balloon into the upper atmosphere and release a "substantial" amount of energy — basically detonating a bomb.
That energy would be channeled upward to increase the density of the atmosphere in a small, specific region where a piece of debris might travel. That was expected to result in giving the junk more drag and forcing it to drop to where it would burn up — thus removing the debris without launching a costly rocket.
But the idea proved infeasible. The amount of energy needed to increase the density in that very small area of the atmosphere was much greater than anticipated. Research also showed there was no way to keep the energy directed completely upward, rather than diffusing to the sides, Ridley said. NASA did not fund further investigations.
"This was definitely outside the box," Ridley said.
Tethers Unlimited, a 40-employee aerospace and defense tech company based in Bothell, Wash., took a different approach, addressing the source of the debris.
It developed a tether and a tape that are attached to a satellite before launch and deployed at the end of a satellite's life. That should increase its drag and pull it back into the atmosphere. The company also came up with a giant net that would capture objects already in space.
The tether was created in the late 1990s and early 2000s, around the time that large satellite constellations were proposed by companies such as Iridium and Teledesic. When many of those ambitious plans collapsed, Tethers Unlimited had to shelve its technology.
"They were interested in the device, but when they all went bust, our market evaporated," company Chief Executive Robert Hoyt said.
A new market could emerge with recent interest in launching small satellites and new constellations. Two of Tethers Unlimited's Terminator Tape products have already launched on small satellites, with a few more set to launch this year, he said.
Debris removal technology is only about 5% of the company's business today. But if everything worked out with the new small-satellite boom, "it could very easily be 10- or 100-fold bigger," Hoyt said.
Aerospace Corp.'s plastic-wrap idea, called the Brane Craft, is being funded with an early stage grant from NASA. Though only in early theoretical stages, it could be a "reasonably inexpensive way" of taking out the trash, said Siegfried Janson, a senior scientist in Aerospace's micro-satellite systems department.
The Brane Craft would be a square, 1 meter wide and 1 meter high. Orbit data for documented debris would be uploaded to the craft, which would then navigate to the correct location through GPS. Once within 200 meters of the target, on-board optical and radio-frequency sensors would lock on and help the craft get close enough for a hug.
Janson is researching nonfreezing propellants for the craft's many tiny ion engines to keep it active once it passes out of sunlight. When it finds an object, the spacecraft would fire those thrusters to drag the debris down to a lower orbit before dropping it.
Janson said he wants to apply for a phase-two NASA grant — which would involve building and testing of parts — after his current funding ends.
Establishing a junk-removal market also would require stricter enforcement of debris removal. Various regulations have been enacted by NASA, the U.S. government and other international agencies; one U.S. rule states that a spacecraft must be removed from orbit within 25 years of its mission's end.
A 2009 paper on the risk and responsibility of space debris by Stanford University researchers Lawrence Wein and Andrew Bradley suggested that stricter enforcement of those regulations, as well as adding penalty fees, could deter future junk generation.
"For these de-orbit technology and debris removal services to really have a market, the laws and regulations are still going to have to evolve where there's some teeth behind the regulations," said Hoyt of Tethers Unlimited.