Miércoles 29 de Junio de 2005, Ip nº 115

Martian life might threaten human mission
Por David L Chandler

Before the US sends humans to Mars, it should rule out the possibility of dangerous life forms on the planet, a NASA advisory panel has reported. And it says the only reliable way to do that is with a robotic sample-return mission - which could take more than a decade to implement.

In January 2004, US president George W Bush announced a plan to send astronauts back to the Moon as early as 2015 and eventually on to Mars. In response, NASA's Mars Exploration Program Analysis Group this month issued a report on research needed to certify the safety of such a Mars mission.

One of the panel's top priorities goes well beyond the scope of any mission in NASA's current plans. The panel concluded that no amount of robotic testing on Mars could rule out the possibility of living microbial life at future human landing sites.

So astronauts could inadvertently bring the life back to Earth, with potentially dangerous consequences. "The possibility of transporting a replicating life form to Earth, where it is found to have a negative effect on some aspect of Earth's ecosystem" would present the greatest biological risk, the team wrote.

Secure facility
But that does not mean a human mission hinges on proving Mars is lifeless everywhere - just in the airborne dust, and in the soil around a future landing site, down to whatever depth the astronauts might reach. To check for life there, the panel recommends NASA dispatch a robotic mission to Mars that would return samples of its air and soil to Earth for analysis.

"If life is found in any sample, it must be assumed to be hazardous until proven otherwise," the team writes. An earlier NASA report found that handling such samples safely would require a new type of secure facility, which would take an estimated 10 years to design and build.

But the new report suggests such precautions are "what the science community believes is important", says John Rummel, NASA's planetary protection officer in Washington, DC, who is charged with preventing microbes from cross-contaminating planets. He says the effort would be worthwhile because the consequences of a mistake - however unlikely - could be so serious.

Dust and dynamics
The panel's other top priorities are:

• understanding the fine dust on the Martian surface, which might pose problems for machinery as well as for people;

• understanding the dynamics of the upper atmosphere, which could be crucial for a safe spacecraft entry and landing;

• learning about potential sources of water that could be used by human explorers. Water could be broken down into oxygen for breathing and hydrogen for fuel.

These three investigations are well within the scope of existing plans for Mars exploration. In fact, the present Mars rovers Spirit and Opportunity have already gathered useful data on the dust - and may get more of it as Opportunity studies the unusual dune it had been stuck in for six weeks. And the upcoming rover Mars Science Laboratory and Phoenix lander - which will be stationary - will learn even more.

  20/06/2005. New Scientist Magazine.