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Japan Moves to Counter Space Debris

June 30, 1998

Space is getting to be a crowded neighborhood. (Courtesy of NASDA)

Japan is taking steps to clean up the space debris that is hurtling around Earth at tremendous speeds, threatening to collide with satellites and render them useless. There are said to be about 35 million objects, large and small, that can be classified as space debris, including pieces of rockets and satellites launched in the past. Japan's countermeasures include construction of a facility to monitor debris by radar and a telescope to help skirt collisions. In the future, Japan hopes to apply its strength in unmanned robot technology to develop a satellite that could collect the litter flying around Earth.

Preventing Collisions
Because of the increased launching of rockets and satellites over the past several years, the amount of space debris is growing at an alarming rate. At present there are thought to be about 8,600 objects with diameters of more than 10 centimeters whose orbits are known; the count rises to more than 35 million when much smaller objects with diameters of just a few millimeters are included.

Space debris rushes along at speeds of around 10 kilometers per second, so the shock of a collision would be terrific. According to experts, a crash with an object measuring just 3 millimeters in diameter would be equivalent to being hit by a bowling ball moving at 100 kilometers per hour. A satellite would be seriously damaged if it received such a blow.

Of special concern is the damage that would occur if a flying object were to collide with the international space station that is scheduled to be built jointly within the next decade by the United States, Europe, Canada, Russia, and Japan. This space station will be the largest structure ever built in space: Its main structure alone will be the size of a small apartment building, and personnel will be permanently stationed on it. The participating countries and experts are naturally very concerned.

For this reason, plans are being made to install thin metal plates on the outside of the living quarters, which would dissipate the energy of a collision with space litter, and also to enable the space station to alter its course if a crash appeared imminent.

Japan's Robot Technology
Japan has decided to strengthen the monitoring setup necessary to forecast potential collisions. According to a plan by the Science and Technology Agency, a dome-shaped radar facility and a large optical telescope with an aperture of 1 meter and a range three times that of an ordinary telescope will be constructed in Okayama Prefecture--considered the best site in Japan for monitoring space--at a total cost of 2 billion yen (14.3 million U.S. dollars at 140 yen to the dollar). The radar facility, scheduled to go into operation in 2004, will be able to track objects 1 meter in diameter at an altitude of about 600 kilometers; the telescope, which is scheduled to be completed in 2002, will be able to trace 50-centimeter objects in stationary orbit 36,000 kilometers above the Earth's surface. These facilities will be able to monitor and calculate orbits for not only space debris but also asteroids approaching Earth.

Obviously, efforts must also be made not to create any more garbage in space. For its next-generation rocket, the H-IIA, Japan is conducting research into recoverable tanks for oxygen and hydrogen to prevent their remaining in space after a satellite launch.

Despite such efforts, space debris is likely to keep on piling up in the future. So what is needed is the development of a "vacuum cleaner" in space. And for this, the world has expressed its hopes that Japan would contribute its leading-edge robot technology.

To learn about Japan's space development, visit the
National Space Development Agency of Japan.

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Trends in JapanEdited by Japan Echo Inc. based on domestic Japanese news sources. Articles presented here are offered for reference purposes and do not necessarily represent the policy or views of the Japanese Government.

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