Recent news concerning the growing amount of space debris should be a major concern for all of us. Thousands of pieces of junk are orbiting the Earth each day with the distinct possibility that some could damage operational satellites, not to mention threatening the safety of the crew and structure of the International Space Station (ISS). This orbiting junk accumulated over many, many years includes old and nonfunctional spacecraft, material from satellites that exploded in space, pieces of satellites that collided with other spacecraft, and other debris as small as paint flecks. Yes, even paint flecks can pose problems for Earth-orbiting satellites and astronauts.
In a span of just four days last month, the space station was alerted two times to the possibility of close encounters with orbiting debris. As noted in a recent article on SPACE.com, “Space Junk Threat Will Grow for Astronauts and Satellites” by Mike Wall, “Fast moving chunks of space debris zipped uncomfortably close to the International Space Station twice in the past week—cosmic close calls that will likely become more common over the next several years, experts predict. And this debris can snowball—as when satellites collide, spawning thousands of new pieces of orbiting junk.”
In the first incidence, the space station had to be moved to avoid a piece of material that resulted from the collision of two satellites in 2009. The second near miss could have been more serious since the debris was not detected in time to execute an avoidance procedure. As noted in the article, it takes about three days to move the orbiting ISS so the crew would have to vacate the station and climb into the docked Soyuz spacecraft. Fortunately, the debris from a destroyed Chinese satellite missed the ISS by enough margin so the astronauts did not leave the lab.
The tally of space junk orbiting Earth is huge. According to the article, 20,000 pieces of junk are bigger than a softball while 500,000 are larger than a marble, and only 22,000 are actively being tracked. Consider that the destroyed Chinese satellite contributed about 3,000 chunks to the junk pile.
Even though some pieces will slow down and eventually burn up as they enter Earth’s atmosphere, many more will take their place as junk collides with junk, creating much more junk. We need to undertake programs to remove the debris we have now—at least the kind that poses the most threat to spacecraft and people—quickly and efficiently.
Many ideas have been postulated I’m sure, but one seems to have taken center stage by the Japan Aerospace Exploration Agency in cooperation with a manufacturer of fishing nets. In “Casting a Net for Space Debris” by Jennifer Ouellette in DiscoveryNews, the concept is to fabricate a suitable metal net that will be attached to a satellite and launched into space. After achieving orbit, the net detaches from the satellite and starts capturing space debris in its path much like a fisherman catches fish in the ocean. After several weeks of junk collecting, the net will slow down sufficiently to re-enter Earth’s atmosphere and burn up.
I assume multiple nets and multiple launches would be required to achieve some modicum of success in removing the unwanted debris. It appears to be a challenging undertaking at the very least with a myriad of technological issues to be resolved. As in net fishing, how do you make sure only space debris is collected and not some operational satellite? At least fishermen can throw back unwanted fish or sea creatures caught in their nets.
Paul Milo
Editorial Director
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