Asteroid of the Half-Month: 25143 Itokawa Part II

Soichiro Honda (yes, that Honda) once got asked the secret of his success. He reportedly said ‘One word: lucky.’ During the rise of Honda and similar manufacturers, Japan was dismissed as a land of cheap knockoffs. That era is clearly done. Japan has done the world’s first asteroid sample return, Hayabusa, though luck (good and bad) was clearly part of its story.

Japan has long wanted asteroid materials. In Jun 1985, nearly two decades before the launch of Hayabusa, a sample return meeting1 was gathered. This itself was after NASA and the NSF led an oversubscribed, 1971 international conference2 on asteroid exploration. In that and the following years, Peak Oil and the embargos added even more urgency if not funding. Through Hayabusa, we found something even more enabling: water in space.

Quick recap: the Hayabusa mission launched in May 2003, reached asteroid 25143 Itokawa, and gathered a sample. It returned in Jun 2010, dropping a reentry pack.

But back to 1985. That year, a Japanese team was assembled to analyze sample returns. They devised a mission to 1943 Anteros and back. Its trajectory was “surprisingly but accidentally very closely identical to the orbit of Hayabusa.” However, given 1985 technology (like chemical rockets) the mission was far too big and heavy (Kawaguchi et al. 2006). But by 1994, the Clementine probe had tested miniaturization, in flight. Crude forms of electric propulsion were flying, and ion thrusters were about to (gradually) take over communications satellites (such as Japan’s own ETS-6). Before Clementine even disbanded, a new Japanese team had formed, to study electric rockets for Mars and Near-Earth Objects (NEOs). They moved fast (for space), publishing a paper the next year on electric-thrust sample return (Kawaguchi et al. 1995). That mission got approved by Apr 1996, the start of Japan’s next fiscal year.

You may be thinking ‘April 1996 approval to May 2003 launch? What took seven years?’

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