|
Thursday, June 10, 2004 Life, Mars, and a Cranky Student Outer space is cool. Or at least this is what people trying to fund space programs for various reasons are wanting you to think. I'm not saying that thinking outer space is cool is wrong, but it is my bias that it is almost an unfair obsession in the public mind. Then again, physicists complain that biologists get too much funding so who am I to argue. A personal experience as an example: As an undergrad I had done some summer research on Magnetospirillum magnetotacticum (a strange microbe thought to use the earth's magnetic field as a guide). At the end of the summer, I gave about a half-hour talk to an audience that was composed of academics, my chemist roommate (for morale purposes) and some laypeople. Almost immediately, people started asking, "Is this going to be helpful in trying to find life on Mars?" For the first second I totally blanked out because not only had I not been expecting that question but I had never mentioned or alluded to anything related to Mars or space. In retrospect, I could see how someone would think of Mars, especially if Mars was already on the brain. Magnetospirillum --> hordes iron --> some iron compounds are red --> Mars! But for goodness sake, couldn't they have just stuck to a topic a little more closer to what I had been talking about for 30 minutes? The speaker at the talk I attended yesterday probably could have fielded that question a lot better than I had. An undergrad had done some work at JPL examining contaminating bacteria in the clean rooms that NASA engineers used to build the Mars probes. The experiment was rather straight-forward: swab samples were taken from various places in the clean rooms as well as the surfaces of the probes. These samples were then cultured to check what would grow out. One would hope that in a clean room, everything would be clean (anyone entering one would have to suit up and take decontamination showers), but that was not the case. Several Bacillus species were cultured from those samples. Okay, so the clean rooms aren't so clean. But would these microbes survive the harsh conditions of space and end up colonizing a planet the probe might land on? Several "stress tests" such as gamma and UV irradiation were administered and at levels greater than that would kill your run-of-the-mill microbe, some of these Bacillus spores were still able to survive. So what does this mean? An alarmist will try to convince you that we have to worry about infectious alien microbes hitching a ride back to earth on a homecoming probe, but what is probably more likely is that an earth microbe is hitching a ride on the probe to places that no man has gone before. Well, why does that matter? you may ask. We're not going to affected. Oh, yes we are. If earth microbes get onto a planet, they could contaminate any data we try to get out of it. This is like mishandling glass slides with your bare hands. If you put that slide under the microscope, you won't be able to tell if the sample you're looking at is really the sample or just your dirty fingerprints. However, extremophiles in the bacterial world isn't a new concept. Bacillus species aren't the only ones able to withstand abnormal amounts of stress. Deinococcus radiodurans, which some hypothesize arrived on earth via meteorite even though more recent data suggests that it has evolved from terrestial ancestors, has been shown to withstand high doses of radiation. The key to understanding how bacteria manage to live under this condition is to look at how it protects itself. Is there something in its cell wall conferring protection? Or is there some more active mechanism? After the talk, I overhead a wannabe med student complain: "Why should we care? We're going to contaminate Mars anyway once a man lands there." True, but I think, scientific reasons aside, that we should keep the rest of the universe as clean as possible just on principle. [posted by S. Y. Affolee on 5:00 PM : ]
Comments:
Post a Comment
Links to this post: |
