Thursday, December 16, 2004
Jeffrey Kargel, a USGS scientist, published a discussion about the significance of Mars's watery past to the prospect of life on Mars today. Eleven paragraphs of dry science are followed by one paragraph on what the possibility that life might exist on Mars today means to human exploration of the red planet. Kargel's conclusion: "Given what we now know about Mars, planetary protection considerations require the assumption that Martian life exists, until we learn otherwise. All possible care must be taken to avoid cross-contamination between Earth and Mars. Before proceeding with sample returns or human missions to Mars, we must review measures for planetary biological protection." (Science, vol. 306, 3 December 2004, p. 1691.)
That's quite a bombshell conclusion Kargel, an expert on cold climates, comes to: we should assume life exists on Mars until we learn otherwise. The significance of his assumption is the worrying part for those of us who advocate human exploration of Mars, not just by sending robots, but by sending people. Kargel's desire to protect Martian microbes and avoid back contamination on Earth leads him to promote very strict limits on sending humans to Mars. He is said to favor sending robots to Mars to search for life there, rather than bringing samples back to Earth or sending humans. If humans do go, he says here "To be humane to them, you send them to Mars first with some reasonable knowledge that they're not going to be infected, so you have to do your homework first." He adds, "Secondly, you give them the means to live on Mars the rest of their natural lives."
It's hard to imagine waiting to send humans to Mars until we have "some reasonable knowledge that they're not going to be infected." First, Mars is a planet. Even though it is smaller than Earth it's surface area roughly equals our planet's land area. To rule out human infection we'd have to send lots and lots of robots to search for life there and essentially rule it out. Waiting until the robots discover life on Mars or rule it out would delay human exploration of the planet for multiple decades. Some space scientists would prefer that approach anyway. Dr. Jeffrey Bada, of UCSD, in a talk hosted by the San Diego Mars Society in 2004 argued against sending humans until we are sure Mars has no life. His rationale was to protect the Martian environment from contamination so that if we do discover life there, we can be sure it is native Martian life and not an Earthling invader.
Second, it's a completely unrealistic and unaffordable mission requirement to ensure that any astronauts we send to Mars will have "the means to live on Mars the rest of their natural lives." Sending humans to Mars will be expensive enough as it is without requiring that the first mission send enough resources for 4-6 people to live on Mars for 25 years or more. (Don't believe the trillion dollar myth. Reasonable estimates for a humans to Mars program range from $30 to $60 billion over 10 years and $2-5 billion per mission after that.) Now, if Kargel were proposing a colonization scheme in which we would send people one way to colonize the planet, that might be something advocates of human exploration could get behind. But that's not what he appears to favor. What he seems to have in mind is a one-way mission sent one time and that's it. That's not reasonable.
Third, although it's more expensive to send humans to space, humans on the scene would do much better science than robots would. Just think about the fact that Spirit and Opportunity travel at about 2 inches per second and consider the distances they've traveled in the year they've been there. Then imagine how far humans might have gone in the same time. Then think about the wealth of knowledge discovered by the rovers and imagine how much more would have been discovered by several scientists working on Mars with a full lab in the same time. There is no comparison. Humans would have accomplished so much more.
We can't let concerns over whether life on Mars is dangerous to us or we are dangerous to it stop us from going there. That would be giving too much counsel to our fears.
NASA already has planetary protection protocols for protecting Mars from contamination and Earth from back contamination. Indeed, the Outer Space Treaty requires such protocols. And it would be irresponsible not to take reasonable protective measures. Which is why it's painful to see Robert Zubrin, founder and head of the Mars Society, saying this: "For NASA to spend hundreds of millions of dollars to prevent Martian microbes from coming to Earth in their samples would make as much sense as for the U.S. government to set up a program to stop travelers from bringing Canada geese across the U.S.-Canadian border."
Well, no, actually, it's not quite the same. While it's true that meteorites from Mars land on Earth occasionally. There is to date no evidence (the controversial Antarctica meteorite notwithstanding) that any Martian microbes have piggybacked their way to Earth on any one of those rocks. As far as we know, nature is not already doing what NASA seeks to avoid. Unlike the flocks of geese which migrate from Canada to the U.S., there are no flocks of microbes migrating from Mars to Earth.
Donald Robertson wrote an essay for The Space Review in 2003, prefiguring this whole debate, "The Mars Train Wreck". He proposed missions to asteroids as a proxy for any permanent Mars base until the issue of biology on Mars can be settled. (In private e-mail to me, he mentioned a manned base on one of Mars' moons instead, since that's about equally ambitious, it would permit near-real-time teleoperation of surface equipment on Mars, and would be good experience for learning how to live on asteroids.)
Jeff Bell weighed in more recently in a SpaceDaily.com op-ed, "The Genesis Strain", invoking an Andromeda Strain scenario for sample return. Of course, Earth might have been "contaminated" long ago by Martian microbes, since quite a few meteorites have been positively IDed as Martian rock. The chances of global ecological disaster would seem to be extremely remote. However, that can't be ruled out, and this is our biosphere we're talking about.
An Ashley Brilliant quip comes to mind: "I can't say what the solution is, but I certainly admire the problem."
Links to this post: