Space science. Japan 'hopes' to avoid crash of ill-fated Mars probe.

Abstract

SPACE SCIENCE The Japanese space agency JAXA has all but given up hope of saving its crippled Mars probe. The only question remaining is whether it will also crash ignominiously into the Red Planet next month. Launched in July 1998, Nozomi (“Hope”) has suffered numerous setbacks, including a fuel shortage and a damaging solar flare. That has delayed its arrival for 4 years. En route, a malfunctioning power system has allowed the craft's rocket propellant to freeze so that ground controllers are now unable to carry out the prolonged firing needed to put Nozomi into its intended orbit. As of now, Nozomi is more or less on a collision course with Mars. If controllers can't solve the fuel problem by 9 December, they will use small alternate thrusters to prevent a possible crash of the spacecraft, which wasn't sterilized before launch. Nozomi will then end up drifting uselessly in a wide orbit around the sun. Nozomi was designed to explore the upper atmosphere of Mars and its interaction with the solar wind. The probe was to have measured atmospheric atoms that escape into space through a variety of mechanisms, providing clues about possible reservoirs of water and other materials. ![Figure][1] Lost hope. Japan's Nozomi spacecraft may crash on Mars or miss the planet completely. CREDIT: JAXA Don't bet on more martian wreckage just yet. According to Nozomi project manager Hajime Hayakawa, there is only a 1% chance that the craft will plunge through the martian atmosphere and crash on 14 December if Nozomi's rocket motor can't fire. But if that happens, the planet might be contaminated with terrestrial bacteria, because “no sterilization has been done before launch,” says Hayakawa. The biohazard risk is also low, according to John Rummel, NASA's planetary protection officer. He cites the extreme dryness of the planet, which is also pelted by blistering levels of ultraviolet radiation. Microorganisms on Nozomi are unlikely to have survived a 5-year trip through interplanetary space, he adds, and those that did would face the partial burn-up of the spacecraft in the martian atmosphere. “It's unlikely that there would be a significant contamination problem,” says Rummel. If Nozomi does crash, it won't be the first contaminated debris to reach the martian surface. In 1999, NASA's Mars Climate Orbiter crash-landed on the surface due to an engineering blunder ( Science , 1 October 1999, p. 18). Like Nozomi, the orbiter was cleaned but not fully sterilized. And many doubt the claims of Soviet scientists that their Mars landers—the first to touch down in the 1970s—were fully sterilized. [1]: pending:yes