"The first concussion cut the rocket up the side with a giant can opener. The men were thrown into space like a dozen wriggling silverfish. They were scattered into a dark sea; and the ship, in a million pieces, went on, a meteor swarm seeking a lost sun.” –Ray Bradbury
Filling up the void
On a Thursday afternoon in March of this year, crewmembers of the two-story International Space Station (ISS) made an emergency evacuation. The reason? A 13-centimeter piece of satellite debris heading towards the ISS at 17,000 kilometers per hour had been detected the night before, threatening to puncture a hole in the space station. The piece of debris’ eccentric orbit gave the crew little warning of the potentially fatal collision. The three crewmembers retreated to a Russian-built spacecraft attached to the station, which would allow the crew to undock and return to Earth. Eventually the object passed by without incident, but the danger of orbital debris isn’t going away. Thousands of like objects are circling the planet every hour, in an ever-growing swarm of speeding trash.
Space is not as vast and empty as we may think. In fact, it’s beginning to fill up. Within Earth’s two main orbits there are roughly 8,000 manmade objects, and only 560 of those are operational satellites—the rest fall into the category of orbital debris. Because no protocols have ever existed to bring defunct satellites back to Earth, orbital debris has been accumulating since Sputnik. As space junk builds up around the Earth, the dangers it poses are becoming increasingly apparent.
So what is orbital debris? So far there is no international consensus on the definition. Generally speaking, orbital debris refers to pieces of old satellites, the remains of rockets, trash, and even tools left behind by astronauts orbiting the Earth. This space trash can vary from paint flecks to whole abandoned satellites. This clutter remains in orbit and threatens collides to spacecrafts, satellites, and other orbital debris itself. According to a discussion conducted by NASA astrophysicist Donald Kessler in March 2009, orbital debris is accumulating in space at about the rate of 300 pieces of waste per year. As of now, the North American Aerospace Space Command (NORAD) tracks about 5,500 pieces of orbital debris in space. The statistical likelihood of a collision seems very small, but the continued accumulation of orbital debris puts future space activities at risk, and the results could be disastrous.
Kessler argues that the buildup of orbital debris could form an actual asteroid belt encircling the Earth. He hypothesizes a domino-effect scenario—known as the “Kessler Syndrome”—in which, as debris hits and breaks up more debris, the actual number of objects will start to increase exponentially. And number, not size, is the problem. In the Lower Earth Orbit, about 2,000 km above the Earth’s surface, objects can hit each other at up to 5 kilometers a second (most bullets can’t go past 1.2 kilometers a second). Even a 5 mm speck of metal poses a serious threat to a satellite or space station. In the worst possible scenario, space debris could render exploration and satellite technology infeasible. So much for Mars.
What goes up must come down
Ideally, defunct satellites and space stations would fall out of orbit and simply burn up upon entering the Earth’s atmosphere. But space is not always self-cleansing. Many of these objects are too large to burn up in the atmosphere, and anything space-bound must be made to withstand incredibly high temperatures, up to 6000 degrees Fahrenheit. What’s more, objects in orbit are built to last: even the smallest ones, depending on the altitude, can stay aloft for as long as 30 years.
Orbital debris’ durability makes re-entry the other half of the problem. Such was the case 30 years ago with the United States’ first manned space station, Skylab. Five months after NASA officials made the decision to abandon the station in 1979, Skylab made its fiery plunge towards Earth. Despite five months of meticulous planning for Skylab’s final moments, NASA scientists and engineers could do nothing but hold their breath. While many had envisioned the long-term use of Skylab, it only functioned in orbit for a little less than a year, as scientists neglected to include booster engines that would keep the station in orbit. As Skylab re-entered the Earth’s atmosphere with increasing speeds, it plunged downwards as a ball of burning metal, breaking into some 500 pieces. Though original projections had expected Skylab to fall into the Indian Ocean, officials later recovered pieces of debris in a remote part of Western Australia. No one was hurt, but Skylab’s fall was a harsh reminder of the science community’s powerlessness in such a situation.
Cleaning up the final frontier
There are no clear solutions for the problem of orbital debris. In 1981, NASA began a 10-year space debris assessment plan, with the goal of laying a foundation for eventual international agreements on the issue. But the responsibility of keeping the space environment clean doesn’t solely rest on the United States or Russia, who arguably conduct the most interstellar activity, with India and China becoming steady contributors of orbital junk. Currently, there is a collective agreement under the Outer Space Treaty to conduct activity with respect to the environment of space. But the language of the treaty is vague, and no legal body has the power to enforce it. In addition, the vast majority of objects in space are commercial, and not yet strictly regulated.
One major obstacle to international regulation of space debris is the high cost of removal. Using military technology to shoot down orbital debris comes with a financial burden that few governments can shoulder. Space agencies like NASA have taken steps to reduce the possibility of satellite collisions by placing satellites at higher altitudes of orbit, where they are less likely to run into other spacecrafts. But this solution is only temporary, as the amount of space in orbit is rapidly filling up. Furthermore, moving satellites into another orbit takes fuel that commercial satellite owners would prefer to use to keep their satellites aloft longer. But, as Chief Scientist of NASA’s Orbital Debris Program Office Nicholas Johnson stated in his 1995 assessment on the issue, initiatives must be taken now, before the effects of increasing orbital junk turn deadly. It is better to meet danger in the face than wait for it.
CLARE KIM B’11 always brings an extra pair of booster packs.