The Feb. 10 collision of a defunct Russian military satellite and a commercial American satellite in the skies approximately 800 km above Siberia — one of the most popular altitudes in low Earth orbit — is worrisome for a world that has grown to rely on satellites for everything from communications and navigation to scientific research and spying.
Taking place at a speed of approximately 42,120 km per hour, the collision turned the two satellites into a cloud of debris that is spreading over a vast area and could eventually ring the planet. It is this rubbish that has scientists, commercial enterprises and governments so concerned. As the amount of junk grows — in February NASA estimated there were some 19,000 objects present in Earth’s low and high orbits, most of which were debris — so does the risk of damage to satellites, spacecrafts and astronauts.
It’s easy to imagine space debris as junk merely floating around, but in reality it moves at an average speed of 10 km per second, posing a serious hazard to spacecraft, satellites and astronauts. A 5-cm fragment can strike with a force equivalent to that of a steel safe smashing into the ground after being dropped from a 10-story window. One chip of aluminum paint measuring 0.2 mm left a 4-mm crater when it struck the Space Shuttle Challenger’s windshield in 1983.
Although the United Nations Committee on the Peaceful Uses of Outer Space (COPUOS) published guidelines in 2007, and last year began discussing international “rules of the road” to prevent satellite collisions, there is no international treaty to mandate policies that would minimize space debris.
At a COPUOS meeting held in Vienna last month, it was pointed out that the collision occurred because the operator of the satellite that could have been maneuvered out of harm’s path was unaware of the threat. A proposal was made to establish an International Civil Space Situational Awareness system, which would provide the location of objects in Earth orbit.
Developing such a system would be very expensive and require a high degree of cooperation among commercial and government users of space. But when one considers the costs if celestial congestion reaches a point where satellites can no longer orbit safely, it is surely worthwhile to pursue such an effort.
Japan is making progress toward becoming a commercial space power, a role that could generate vital funding for its space program. In January, Mitsubishi Heavy Industries won its first commercial order to launch a satellite on an H-IIA rocket. Just last month the Japan Aerospace Exploration and MHI unveiled the new H-2B rocket, which can carry heavier payloads and should boost Japan’s competitiveness in the commercial space launch market. With much at stake, Japan should play an important part in efforts to establish systems that can monitor space debris and help prevent collisions.
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