The following is an article from Uncle John's Bathroom Reader The World's Gone Crazy.
(Image credit: Miguel Soares)
Imagine a shiny screw—just a screw—tumbling through space. Ahead is a man, oblivious, protected only by his spacesuit. He takes a break from his work to admire the view of the blue-green Earth hanging in the blackness of… WHAM!—the screw pierces the man’s leg and shoots out the other side! He screams as the oxygen is sucked from his lungs …and the blood-red screw continues on its way.
OUT OF SIGHT, OUT OF MIND
A vast junkyard of potentially lethal projectiles surrounds our planet, and it’s been accumulating since the 1950s. For decades, space programs in the United States, the U.S.S.R., and other nations followed a similar process: Build a satellite, attach it to a rocket, and blast it into space. Once out of Earth’s atmosphere, the satellite separated from the rocket and went into its planned orbit. But what happened to the rocket? No one gave it too much thought; after all, space is big, and rockets are tiny in comparison. And so, too, are the satellites, which had only limited battery life to begin with. So all that equipment floated in space, and there was no plan in place to dispose of it. Occasionally, leftover fuel would build up pressure in an unventilated tank and cause an explosion. When that happened, what was once a rocket transformed into a cloud of floating debris. And as more countries joined the space race, even more rockets and satellites were launched into orbit.
Today, in addition to about 900 operational satellites, there are nearly 2,500 derelict ones up there. The oldest of them is the second satellite the United States ever launched, Vanguard 1, which has been orbiting Earth since March 17, 1958.
TOO MANY ODO’S IN THE LEO
The part of space that is most crowded with old junk is, not surprisingly, the part that’s easiest to get to and the most useful to us. More than half of all satellites—along with the International Space Station and any spacecraft that happen to be flying—circle the planet within a range of altitude called Low Earth Orbit (LEO), which stretches from about 124 to 1,240 miles up. (By comparison, the moon is more than 200,000 miles away.)
The problem with filling this most useful of altitudes with junk is that the junk doesn’t just float around harmlessly up there; it’s actually moving incredibly fast—at an orbital speed of up to 17,000 miles per hour. At speeds like that, even the smallest debris particle can cause significant damage to whatever it hits; tiny flecks of paint and pieces of grit have been shown to pit the surface of expensive satellites. And a direct collision with anything larger than about a half-inch in diameter could actually destroy a satellite—or, for that matter, a manned spacecraft.
To counter these dangers, NASA and other space agencies try to catalog and track every piece of junk they can. The United States Space Surveillance Network monitors the location of more than 19,000 individual orbital debris objects (ODOs). But, unfortunately, the network can’t track anything smaller than about four inches across. NASA estimates there could be as many as 500,000 ODOs that are big enough to wreck a spacecraft but too small to track from Earth.
THE KESSLER SYNDROME
It wasn’t until the late 1970s that the space program looked at this problem head-on, after NASA scientist Donald Kessler and his colleagues warned that LEO could become so crowded that it would no longer be safe to launch new missions. If an item as small as an old bolt or screw could destroy a spacecraft, Kessler told them, imagine what an entire defunct satellite could do.
In February 2009, scientists had the opportunity to find out: A 2,000-pound decommissioned Russian satellite crashed into a still-operational 1,200-pound American model, obliterating both crafts and turning them into a dense cloud of dangerous debris. That event—the rendering of two large objects into thousands of smaller ones, each capable of going out on its own to destroy other spacecraft—is called the Kessler syndrome. Space junk multiplies at a constantly accelerating pace: More junk equals more collisions, and more collisions mean more junk. Even if humans never launch another rocket, the number of ODOs will still continue to multiply.
(Image credit: Miguel Soares)
Not helping matters, in 2007 the Chinese government shot down an old communications satellite, presumably just to show they could do it. The test, which was deemed a success by the Chinese, added thousands of objects to the catalogue of ODOs. The following year, the United States also shot down one of its own satellites—supposedly because it was on a course to crash back to Earth with a full tank of toxic fuel. Now it’s 1,000 toxic bits and pieces.
In 2009 the danger of space junk made big news when three crew members aboard the International Space Station had to evacuate into a waiting spacecraft because a five-inch chunk of an old rocket was heading straight for them. Thankfully, it missed. Afterward, NASA acknowledged that debris comes close enough to the station to cause concern several times per month, and the station has to take evasive action to avoid a collision about once a year.
FAR OUT
(Image credit: Miguel Soares)
Unfortunately, the technology to clean up LEO doesn’t exist yet. But there is good news: The closer an object is to Earth, the less time it will last up there. The reason: The planet’s atmosphere, thin as it is at very high altitudes, exerts drag on objects in orbit, causing them to slow down. As they decelerate, they fall and typically burn up as they enter the thicker lower atmosphere.
Moving farther away from the planet, however, that atmospheric drag decreases exponentially—just a small change in altitude translates into a large difference in how long an object can expect to remain in orbit. A piece of space junk that would last only a few months at 150 miles up could last for years at 600 miles, decades at 800 miles, and centuries at 1,000 miles.
Because of this, most new satellites are designed to fire their rockets one last time when they come to the end of their operational lives. The blast moves them either low enough that they will crash back into the atmosphere, or up into a “graveyard orbit” of more than 22,000 miles—high enough that they are thought to be out of the way (for now).
MORE DIRT ON SPACE JUNK
(Image credit: ESA)
Along with old satellites and booster rockets, there’s a lot of other random stuff hurtling through space. For example:
• 480 million copper needles: Launched by the U.S. military in 1963, the needles, which were only the width of a hair, were meant to disperse around Earth and act as a sort of giant space antenna. It was hoped that this system would replace undersea cables for transatlantic communications, and it worked …for a while. Then the needles drifted a little too far apart and the radio signal gradually weakened, rendering the needles obsolete.
• Nuclear reactors: The United States put only one nuclear reactor in space, in 1965, but it’s still orbiting about 700 miles up. The Soviet Union, on the other hand, shot more than 30 nuclear-powered spy satellites into orbit between 1967 and 1988. Aside from a few accidents (including one that crashed into Canada in 1978), the reactor cores were shut down and boosted into a graveyard orbit at the end of their lives.
• Tiny droplets of radioactive liquid: When those Russian spy satellites shot their reactor cores into a graveyard orbit, there was often some coolant loss…leaving behind millions of globules of radioactive goo.
• Stuff dropped by astronauts: In 1965 Ed White became the first American to walk in space. Tethered to his Gemini space capsule, White lost his grip on a spare glove and could only watch as it floated away. Spacewalking astronauts have been dropping things ever since. Among the lost items: cameras, springs, screws, bolts, grease guns, pliers, and, oddly enough, a spatula.
• Other astronaut “stuff”: On manned spacecraft, urine and fecal matter is (to use a nautical term) “dumped over the side.” In September 2009, the Space Shuttle Discovery discharged 150 pounds of waste (about 10 days’ worth that had built up while the shuttle was docked with the International Space Station). Viewing conditions were just right—the liquid portion of the waste crystallized into a majestic plume that was visible from Earth.
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The article above is reprinted with permission from Uncle John's Bathroom Reader The World's Gone Crazy.
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