The Japanese space agency JAXA has all but given up hope of saving its crippled Mars probe. Launched in July 1998, Nozomi ("Hope") suffered numerous setbacks, including a fuel shortage and a damaging solar flare, delaying its arrival at Mars till mid December, 4 years later than originally intended.
That's not the end of the bad news. 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 in the intended orbit around Mars. To make matters worse, Nozomi is more or less on a collision course with the Red Planet. 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.
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. Therefore, JAXA will attempt to retarget the spacecraft to further reduce the probability of hitting Mars.
The biohazard risk is also low, according to John Rummel, NASA's Planetary Protection Officer. He cites extreme dryness of the planet, which is also pelted by blistering levels of ultraviolet radiation. Moreover, microorganisms on Nozomi are unlikely to have survived the 5-year stay in the hostile environment of interplanetary space. And if they did, they 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 time that terrestrial microorganisms may have reached the martian surface. In 1999, NASA's Mars Climate Orbiter crash-landed on the surface due to an engineering blunder (ScienceNOW, 23 September). Like Nozomi, Mars Climate Orbiter was cleaned, but not fully sterilized. And back in the early 1970s, Soviet space engineers asserted that their Mars landers--the first to touch down--were fully sterilized, but, says Rummel, "their claims were so extreme that hardly anyone believed them."