The stuff of legend

By the time its odyssey ended this month in the Australian outback, the spacecraft Hayabusa had been gone three years longer than planned, lost its main engine, disappeared from all interplanetary notice for more than seven weeks and may have failed to perform its main mission.

Yet the voyage was justifiably and immediately hailed as the stuff of legend. Against all odds, the Japanese space agency, with support from NASA, managed not only to bring Hayabusa back to Earth but also to do something never done before: take a sample from the surface of a distant asteroid and bring it home for study.

"Really, when we saw it land, we could not believe what had happened," said Norimitsu Kamimori, the Washington representative of the Japan Aerospace Exploration Agency, or JAXA. "We hoped, but we never really thought Hayabusa would make it back."

The American public is understandably focused on the feats of NASA and missions funded by American taxpayers. But the exploration of space has become an increasingly international affair, and several dozen nations have space programs of their own or in conjunction with partners.

The Japanese space agency is hardly the largest, and its program is far from the most ambitious. But the Hayabusa mission now has a special place among space-faring nations; its accomplishment ranks somewhere between the life-or-death engineering that brought Apollo 13 back to Earth safely and the long-lived rovers Spirit and Opportunity, which were designed to last 90 days on Mars but are still beaming information and photos back after six years.

'An incredible feat'

Anthony Carro, NASA's program executive for Hayabusa, called the return "an incredible feat." Much of the spacecraft was crippled, he said, "but the Japanese flight controllers were ingenious in figuring out ways to combine the powers of what they had, and they brought it back."

NASA project scientist Donald Yeomans called the return "well beyond remarkable and into the miracle stage."

The Hayabusa mission launched with great fanfare in 2003 and headed for the asteroid Itokawa, an irregularly shaped rock that orbits between Earth and Mars, far away from the crowded asteroid belt between Mars and Jupiter.

It was the most ambitious Japanese space mission to date, and it used both a traditional chemical-fueled rocket engine and additional ion engines, a novel use of microwave technology that moves the spacecraft by heating xenon gas. It's a very energy-efficient way to travel, and that came to be extremely important in the odyssey.

The spaceship reached the asteroid more than two years later, after traveling 1.25 billion miles. At that point in its asymmetrical orbit around the sun, the asteroid was almost 200 million miles from Earth.

Itokawa is often compared to an inflated baked potato about a third of a mile long. It has virtually no gravitational pull, which is what made feasible the goal of touching down, picking up a sample and flying off. But it was difficult, since the asteroid was spinning. The spacecraft carried an instrument akin to a pellet gun that was designed to fire into the asteroid's silicon- and iron-based rocks. Once the gun was fired, the plan was for Hayabusa to snag some of the flakes kicked up from the rocks.

Technical difficulties

As explained by Kamimori and JAXA releases, what happened after Hayabusa caught up to Itokawa was a series of technical problems that seemed to doom the mission. First, an attempt to send the spacecraft's small robotic rover Minerva to the asteroid to take pictures and temperature readings failed. The rover, which was powered by its own small engines, never touched down on the asteroid and inexplicably drifted off into space and vanished forever, according to JAXA mission control.

Then, Hayabusa landed on Itokawa and stayed for 30 minutes, but the pellet gun didn't fire. Researchers hope that some asteroid dust was pulled into the sample box, but it's almost certain that no rock flakes were collected. (next page »)