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2010年6月16日 (水)

はやぶさ帰還 歴史的快挙を次に生かそう

The Yomiuri Shimbun (Jun. 16, 2010)
Hayabusa's achievements should be built on
はやぶさ帰還 歴史的快挙を次に生かそう(6月15日付・読売社説)

Hayabusa, a space probe of the Japan Aerospace Exploration Agency, has finally returned to Earth. This is a great accomplishment in the history of space exploration.

Hayabusa, which means peregrine falcon, left Earth in May 2003. It landed on Itokawa, an asteroid 300 million kilometers from Earth, in November 2005 and attempted to take samples of sand and other surface materials there. The probe's entire space voyage lasted seven years, ending with its homecoming on Sunday.

Hayabusa is the first space probe to return to Earth after landing on a celestial body other than the moon.

The probe's main body burned up upon entering Earth's atmosphere, but before that it released a capsule, which landed safely in the desert in Australia, that may contain samples from Itokawa. JAXA will bring the capsule back to this country and confirm whether it contains sand or other materials from the asteroid.

Unlike sand and stones on Earth, which have become oxidized and changed over many years, geologic material on asteroids is believed to have remained as it was in the early stages of the solar system. Such material would give important clues to understanding the history of the solar system.

Unfortunately, however, it is not certain whether the probe actually was able to take samples of surface material, since Hayabusa's gathering device did not work as expected. But JAXA said that sand stirred up when the probe landed on the asteroid may have entered the capsule.


Miraculous engines

Needless to say, the return of Hayabusa itself is a miracle. The probe experienced technical and mechanical malfunctions throughout its systems as it traveled a total distance of 6 billion kilometers, 40 times the distance between the sun and Earth.

First, fuel leaked from one of Hayabusa's chemical engines after it left the asteroid to return home, which caused JAXA to lose control and later communications. Although the agency fortunately was able to restore communications and put Hayabusa back on its homeward journey in 2006, JAXA had to constantly walk a tightrope for the remainder of the probe's long space flight.

Almost all the probe's devices malfunctioned, but a new type of engine manufactured by a Japanese company did outstanding work.

Called ion engines, these new thrusters have much weaker propulsion than chemical engines, which expel jets of high-pressure gas. The power of an ion engine's thrust could only keep a 1 yen coin aloft on Earth, but it can work for long hours on far less fuel than a chemical engine needs. The ion engines were used for a total of 40,000 hours to control the probe's attitude.

This, along with the automatic control technology that made it possible for the probe to land on the asteroid, demonstrates to the world how advanced Japan's technology in space exploration is. We can expect Japanese-made ion engines to be sold to other countries for use in their space probes and satellites.


Don't block progress

However, we are concerned with the next project. Development is currently stalled on Hayabusa 2, which is intended to conduct higher-level exploration of another asteroid. Learning from the lessons of Hayabusa's development, which cost 13 billion yen, the new project's budget is set at almost the same amount.

Nonetheless, the Education, Culture, Sports, Science and Technology Ministry's budget for space exploration was cut drastically, a victim of the Democratic Party of Japan-led government's plan to make high school education free, which costs nearly 400 billion yen.

Funding this fiscal year for Hayabusa 2 was cut to just 30 million yen, compared with the 1.7 billion yen made in its budgetary request before the DPJ took office from the Liberal Democratic Party.

The government should spend money on a meaningful project, rather than on handout measures.

There could be a blank period of more than 10 years until the next space probe project, given the positional relationship between Earth and asteroids. Memories of the successful space mission could fade during this downtime.

There must be no retreat in efforts to pass important technology in space exploration to the next generation of scientists and engineers, so they can improve it further.

(From The Yomiuri Shimbun, June 15, 2010)
(2010年6月15日02時04分  読売新聞)


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