SEPTEMBER/OCTOBER 2007
BY LUCY MELE
Less than a thousand miles from your scrap facility is more than 2,000 tons of exotic nonferrous scrap just waiting to be recycled. Before you schedule a pickup, however, there’s just one catch: The scrap is up to 1,000 miles straight up, orbiting the Earth.
Thousands of man-made objects are floating around in low-Earth orbit, and most of them are metal, according to Nicholas Johnson, chief scientist for orbital debris at the NASA Johnson Space Center (Houston). “Space debris” is the name scientists use for all nonfunctioning man-made items. “It can be anything that was made by man but is no longer doing what it was supposed to do,” says Bill Ailor, director of the Center for Orbital and Reentry Debris Studies at The Aerospace Corp. (El Segundo, Calif.).
Objects range from camera lens covers to detached rocket stages to defunct satellites. “There is miscellaneous debris, which includes fragments of exploded spacecraft, and also debris which is intentionally thrown away, normally during the launch deployment process,” Johnson says. In July, an astronaut at the international space station threw out an ammonia tank weighing more than half a ton and a 200-pound camera mounting stand, according to news reports.
In total, the U.S. Space Surveillance System tracks more than 15,000 debris objects larger than 10 cm in diameter, most of which are primarily aluminum. NASA estimates there also are tens of millions of debris particles less than 1 cm in diameter.
Orbiting Obstacles
Though 95 percent of orbiting objects are nonfunctional, 5 percent are still operational—and potentially under siege from the other 95 percent. Most spacecraft have shields, or bumpers, to deflect debris smaller than 1 cm, Ailor says, but the bumpers do not guarantee that the debris will not harm the spacecraft. “Something the size of a pencil eraser is a concern to the space station,” he says.
Such collisions are unlikely, but “extensive work is being done to track anything that might be a hazard, and, on occasion, it has been necessary to move spacecraft away from those things,” Ailor says. “If it’s a piece of debris, you can’t move the debris. You have to move the spacecraft.” The space shuttle has been moved more than eight times to avoid potential collisions, he says.
NASA’s Johnson plays down the risks, though. “Spacecraft are being hit by various debris every day, both man-made and natural,” he says, “but the odds of a collision with a piece of debris that would disable the spacecraft are exceptionally small.” The only known disabling collision between two tracked objects occurred in 1996, when a piece of debris struck a French spacecraft. “The spacecraft was temporarily disabled,” but fortunately “the French were able to regain control of the spacecraft and continue its mission,” Johnson says.
Pieces of space scrap often collide with each other, too. According to the NASA Web site, space debris travels between 25,000 and 29,000 km an hour while orbiting Earth. When a piece of debris collides with another space object, the impact speed is approximately 36,000 km an hour. The result? More debris.
Bringing it Back to Earth
What is the likelihood that space debris will make its way out of orbit, into the Earth’s atmosphere, and on to the ground? Johnson says it’s a function of altitude. “At 200 miles up, objects will typically fall back to Earth within weeks or months,” he says. Objects at higher altitudes “can take years or decades or centuries. The higher altitude you are, the longer it takes to fall back to Earth.”
According to a NASA guideline that the international community recently has accepted, all space agencies must ensure that their spacecraft come down within 25 years of launch. Spacecraft that operate at a low altitude will come down naturally within that time frame; for those operating at a higher altitude, the spacecraft or rocket must move itself down to a level where it will fall naturally.
Over the last 45 years, an average of one man-made object has fallen from orbit into the atmosphere each day, Johnson says. This might sound like the perfect opportunity for recyclers, but most of the debris pieces do not survive reentry. “When something enters the atmosphere, you basically have the heat rising, and the lower-melting-point materials like aluminum will melt away,” Ailor says. Pieces that reenter the atmosphere lose 60 percent to 90 percent of their mass.
And then there’s the problem of where they fall. “The minority that do survive typically fall into the water, or they fall into desolate regions like Siberia, the Canadian tundra, or the Australian outback,” Ailor says.
There have been exceptions, however. In 1997, a 570-pound stainless steel propellant tank from a Delta II rocket plummeted from low-Earth orbit into the atmosphere, landing just 50 yards from an occupied farmhouse in Georgetown, Texas. (Falling space scrap has never caused documented human injury or significant property damage, Johnson notes.) A 66-pound titanium sphere was found in the nearby town of Seguin, and another small piece of debris that’s most likely from the same rocket landed near Tulsa, Okla. NASA recovered the debris and moved it to the Johnson Space Center, where scientists studied it before turning it over to the U.S. Department of Defense.
“None of these things can be reused,” Johnson says. “They could be museum pieces, or you could scrap them if you wanted to.” He notes, though, that “the debris remains the property of the launching countries,” thus a space recycler “would officially need the permission of the satellite’s owner before it could be moved.”
What Is It Worth?
In theory, the value of space scrap depends on its condition, says Gregory Mitko, an account executive for Metal Management Aerospace (Hartford, Conn.). “Brand-new, aviation-grade aluminum sells for anywhere from four to six bucks a pound,” he says. “As scrap in good condition, we might pay 50 cents to a dollar a pound. ... If it’s riveted and has other attachments, it might be 30 cents a pound.” The pieces that fell in Texas and Oklahoma could be fairly valuable, he says: The titanium sphere could be worth up to $400; the propellant tank, up to $1,100.
That’s if they’re safe, though. Mitko says he has serious concerns about the potential hazards space scrap could contain and he would have to consider many things before processing such material. “I’d have to do some more research on it. If something fell out of space, I’d wonder if there was something in it,” he says. “It’s been in space, it may be radioactive. If the Geiger counter goes off, we’re not interested.”
Though no one is seriously thinking about collecting scrap from low-Earth orbit today, who knows what the future might bring. The abundance of scrap circling the Earth could tempt a company willing to boldly go where no recycler has gone before.
“If it were feasible, we’d be the first ones in line to recycle this material,” Mitko says. •
Lucy Mele is a writer based in Fairfield, Conn.
Less than a thousand miles from your scrap facility is more than 2,000 tons of exotic nonferrous scrap just waiting to be recycled. Before you schedule a pickup, however, there’s just one catch: The scrap is up to 1,000 miles straight up, orbiting the Earth.