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Waste in Space

Raymond Sedwick, associate professor of aerospace engineering
Fall 2014 Innovation

New UMD Center Seeks to Limit Junk in Orbit

By David Kohn

In 1957, space was utterly, pristinely free of humanity. The Russians sent up Sputnik that year, and since then, humans have polluted space with all manner of flying machines and the junk that breaks or falls from them. These millions of objects, including rocket boosters, fuel tanks, screws, paint flecks, even a spatula, zoom around the Earth at speeds of up to 25,000 mph.

This ever-growing detritus could collide with satellites or other spacecraft, experts say. If left unchecked, it has the potential to eventually cripple global communications and space-based scientific research.

“The risks are growing,” says Raymond Sedwick, associate professor of aerospace engineering. “If we don’t deal with it, eventually it’ll be too late.”

He recently launched the Center for Orbital Debris Education and Research (CODER), which he hopes will become a focal point for academic, industry and government research collaboration.

“There is a real need for a center like this,” says David Spencer, a professor of aerospace engineering at Penn State University who has been studying space debris for more than 30 years. “Right now we don’t have a centralized clearinghouse that includes private industry, government and academia. I think this center will do that.”

No brooms for this debris. Space debris comes in all shapes and sizes, with the smallest detected by ground-based radar and the U.S. Space Surveillance Network tracking the largest: 100,000,000+ at smaller than 1 centimeter diameter. 500,000 at between 1 and 10 centimeter diameter. 22,000 at larger than 10 centimeter diameter. One of the largest pieces of debris is the Envisat Earth-observing satellite, which lost contact with its handlers in 2012. The $2.9 billion spacecraft is the size of a school bus. Two events created about one-third of all orbital junk: In 2007, China used a missile to blow up an old weather satellite, and two years later. American and Russian communications satellites collided. The greatest concentration of all debris is 460-500 miles above the Earth's surface. Most of that will stay aloft for decades before falling to Earth, while debris higher than 600 miles will remain in orbit for a century or longer.

Sources: Nasa, Raymond Sedwick

Sedwick first began working on the issue when he teamed up with a small aerospace company to develop a vehicle that could guide large pieces toward the atmosphere, where they would burn up during re-entry. The project was discontinued, but Sedwick was hooked.

He realized that although several government agencies and the military are working on the problem, there was no academic center devoted to space debris. He and his colleague, Marshall Kaplan, a visiting professor of aerospace engineering at UMD, set out to close this gap, and in May, after two years of planning, CODER was born. Sedwick is now talking to industry and government agencies about funding for specific projects.

The most pressing issue is the several hundred pieces that are the size of a car or larger. The larger the object, the more likely that a collision with a working satellite will produce more debris. Reducing this risk will require removing many of these large objects from orbit. Possible solutions include attaching sails or tethers to the objects to change their trajectory.

But the center won’t only look for technological solutions; Sedwick says CODER will also examine the issue from scientific, legal and economic angles. For instance, he says, it’s unclear whether one country is allowed to clean up the rubbish left by another.

“Who’s in charge of cleaning up orbital debris?” he says. “There is no agreement. Even within our own government there is no policy on this. Is it NASA? Is it the Department of Defense? There is so much we need to figure out.”

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