Space/Science — HabitableZone

Space/Science » in reply to re: Since When Are You So Shy?

Lock And Key Mechanism
Mark Eby — (archived)

Tom,

Are you familiar with the lock and key mechanism of enzymatic function? It is simple extrapolation from this basic and proven model to see that it is extremely unlikely for an alien microbe to compete with a native one to consume a local nutrient. I believe this is part of the basis both for low risk of back and forward contamination assessments by the NRC report.

I agree that theoretically an Earth microbe could survive under conceivable conditions on Mars and vica versa. What I disagree with is that on a relatively inactive and frozen planet local surface contamination is likely to spread before the local harsh conditions sterilize the contaminants or they are consumed in their weakened state by local microbes (assuming compatible biochemistry). It is quite conceivable that local sample could become contaminated, but there are ways to identify that contamination and use a human mission to vastly improve the effectiveness of remote robotic missions in uncontaminated areas. These mitigating circumstances do not however warrant disregarding the issue entirely. They just indicate that unreasonably costly measures are not justified.

I do agree that initial discoveries of life on Mars should be followed by robotic missions to answer fundamental questions most likely to be obscured by contamination and to determine ways to minimize the impact of the human missions likely needed for detailed study of any Martian life found.

Regards,
Mark

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