SPACE – THE FINAL JUNKYARD

This long-for-a-blog piece by Keay Davidson in the SF Chronicle was sent over by MrMR who knows I like this kinda thing and probably figured that I would shamlessly reproduce it in full. Not only does it detail all the crap we’re dumping into low orbit, but also talks about my favorite piece hardware I’ll never live to see – the Space Elevator.

Outer space is fast filling up with human-generated junk, from exploded satellites to leaky nuclear reactors, and the debris threatens the safety of cosmic exploration.
International agencies have met for years to try to solve the problem. One possible solution is to encourage space-launching nations to build sturdier rockets that don't blow up in space and spew debris everywhere, ones that burn up in the Earth's atmosphere upon their return.
Another is to have inventors develop futuristic laser beams that can "sweep" space junk from the skies. Meanwhile, the space-junk problem is getting worse as the terrestrial world becomes more and more reliant on the sky: We increasingly depend on satellites for duties as diverse as cell-phone calls, TV broadcasting, military reconnaissance and guided hikes by global positioning systems. Satellites are used to track robotic minisubs in Antarctica and animals in the wild.
Space junk ranges from human waste to a discarded Russian spacesuit. The latter was recently dumped by the crew of the international space station; later this year, it should fall back to Earth in a blaze of glory. In the 1960s, U.S. tracking systems monitored an American astronaut's discarded glove, which eventually returned to Earth. This summer, a Russian cosmonaut reportedly plans to hit a gold-plated golf ball from the international space station as part of a paid promotional stunt for a golf-club firm in Toronto. That'll add to the floating litter.
About 18 collisions of existing satellites -- 11 of them "catastrophic" to the objects that collide -- will probably occur over the next 200 years, even if Earth never launches another rocket, reported two officials at NASA's Orbital Debris Program Office in Houston in the Jan. 20 issue of Science magazine. In reality, wrote Jer-Chyi Liou and Nicholas Johnson, the actual number of collisions "will undoubtedly be worse" because new spaceships -- that is, future space debris -- are continually being launched.
"Since the launch of Sputnik 1 (in 1957), space activities have created an orbital debris environment that poses increasing impact risks to existing space systems, including human space flight and robotic missions," Liou and Johnson said.
Especially endangered, some experts say, is the most romantic notion on visionaries' wish list: the "space elevator." As proposed, the elevator would be a titanic, super-strong metallic ribbon stretching from close to Earth's surface to a point more than 60,000 miles high, on which elevators would ferry freight and humans into space at bargain-basement rates.
"Low Earth orbit," as it's called, is so packed with debris and satellites that a collision with the elevator, if it's ever built, is a near certainty. One expert's calculations show satellites and debris might collide with the elevator up to several times a year unless the elevator is continually monitored and moved out of the way of an incoming projectile.
"I would love to ride a space elevator to orbit in a few decades -- and I don't want to have to dodge space debris as I'm passing the 1,000th floor!" said George Whitesides, executive director of a leading space activists' group, the National Space Society in Washington, D.C. "We need to control space debris today to make future space development truly feasible."
Space collisions aren't just a futuristic threat: NASA and the world's other space agencies have been dodging celestial bullets ever since the first satellites soared heavenward a half-century ago. When space shuttle astronauts visit satellites to repair them, they find the crafts pitted with tiny craters -- the result of high-speed collisions with paint flecks or other debris. A paint fleck might sound trivial, but as every high school physics student knows, a mere speck carries a lethal punch when it's flying at several miles per second.
Fortunately, paint flecks and much larger debris -- dead satellites and discarded booster rockets -- eventually fall back to Earth and burn up in the atmosphere. But some debris is orbiting so high that it won't return to Earth for thousands of years. And the satellites and other discarded equipment that make up that debris will be ramming into each other, spewing paint flecks and transistors and rubber tubes like busted piZatas at a children's party. As a result, experts say, the overall amount of space debris will grow for decades even if NASA and every other space agency never launches another rocket.
"We still have a lot of stuff up there that was put up there years ago, and it is going be there for a long time," said aerospace engineer William Ailor, director of the Center for Orbital and Reentry Debris Studies at the Aerospace Corp. in El Segundo (Los Angeles County). Until such high-flying swarms of junk return to Earth, they'll continue colliding with one another, generating even more junk. "We've got more collisions coming -- it's going be a fact of life," Ailor added.
As big as a minimall, the manned space station is a juicy target for debris. If a big enough chunk of junk struck it, the result would be a tremendous crashing sound and flash of light inside the station; the station might fill with fog. These effects might disorient the crew members, preventing them from taking emergency actions.
In their report in Science, Liou and Johnson said the U.S. Space Surveillance Network is tracking more than 9,000 pieces of human-made debris. They said the pieces are big enough to be monitored by radar or ground-based telescopes. And that stuff is just the tip of the iceberg; far more is too small to be monitored.
Ailor said that among the stranger debris is a Russian satellite with an onboard nuclear reactor that is "leaking liquid metal -- something like 70,000 blobs of liquid metal (so far)." He said the world's space agencies are collaborating on ways to develop anti-debris protocols for future launches.
For example, he said, exploding satellites and rocket boosters, a major source of debris, can be prevented if launching nations agree to take precautionary steps, such as ensuring their satellites dump leftover propellant after the mission ends in space. The propellant would vaporize, preventing it from exploding if pinged by a meteoroid or other debris. Meanwhile, inventors are investigating far-out ways of tidying up our celestial backyard. Almost everyone's favorite idea involves lasers.
In theory, powerful ground- or space-based lasers could heat the surface of space debris, vaporizing its upper surface. This would cause the debris to expel gases. The gas expulsion would act, in effect, as a brake on the debris' orbital motion, for the reason identified by Isaac Newton three centuries ago: A force generates an equal and opposite reaction. Thus the debris would slow down until it fell back to Earth.
A leading champion of laser-driven cleanups is Claude Phipps, who received his doctorate in plasma physics at Stanford and is president of a laser company, Photonic Associates LLC of Santa Fe, N.M. He has investigated the space debris problem with colleagues from the national weapons laboratories and other institutions.
Experts estimate there are "300,000 debris objects in the 1- to 10-centimeter diameter range," Phipps said. "These are ... difficult to track and lethal if they strike a space asset. They are also becoming more numerous due to collisions, and it is conceivable that they could deny us access to space in the future."
Space debris, though, has stirred the biggest debate within the arcane world of space-elevator research. The elevators exist largely on the drawing board, but there have been field tests of small prototypes on Earth. The No. 1 obstacle to real space elevators remains the development of materials strong enough for the task. Some experts think carbon nanotubes will do the job.
"It's very likely -- I'd say certain -- that we don't yet understand all the ways a space elevator can fail, so the current designs may well underestimate how much damage a small impact could do," said Jordin Kare, who has a doctorate in astrophysics from UC Berkeley and is now a private consultant to the aerospace industry in Seattle.
A veteran researcher on the subject, Bradley Edwards, formerly of Los Alamos National Laboratory, disagrees. He is confident that the space elevator can be safely moved out of the way before space debris hits it. Thus "we can eliminate any concern related to space debris."
Kare counters that such "an active system will always have a chance of failure, whether through mechanical failures, or plain old human error." He wryly imagines this frantic exchange between the tracking officials and the elevator operator: "Move the ribbon left! No, the other left!"
While the elevator is still just pie in the sky, the space debris problem remains very real. Ailor worries that nothing will be done to adequately tame the celestial shootout "until something really bad happens."
"Things are really getting busy up there," he said.

Space Clutter -- An animated illustration of radar-tracked space junk circling Earth can be found at www.aero.org/capabilities/cords/