I was talking to my first officer this week during one of our flights, and as I explained to him what I’m working on we got onto the subject of planetary protection. At the Mars Society conference they spent a fair amount of time discussing this particular topic (as they usually do), and it occurs to me that there are some important aspects to the discussion that are frequently overlooked.
The principle of planetary protection as it relates to Mars (as well as most other celestial bodies) basically asserts that we have a responsibility to protect any indigenous life forms that currently occupy the planet. There are other aspects to the concept such as preserving natural resources and preventing the possibility of introducing invasive lifeforms to Earth’s ecosystem, but most discussion currently revolves around protecting potential life that may currently exist on Mars. This is a valid concern in light of recent discovery of liquid water reservoirs on the planet that may provide suitable habitats for microbial life, and there’s a camp of scientists who argue very convincingly that it would be irresponsible for us to go to Mars until we have determined whether or not there is life there.
The problem as I see it is that this argument has one blaring fallacy- an elephant in the room that no one seems interested in acknowledging. The challenge of proving whether life exists on Mars seems pretty black and white at first glance. Either life is there or it isn’t. True, the Viking landers in the early 1970s provided (arguably) false positive indications of Martian life, but if actual life forms or their fossil remnants are actually observed (as opposed to metabolic byproducts that might be associated with biology) it will prove conclusively that there is life. If we see cellular organisms the argument is essentially over.
This is a pretty cut and dry grounds for a positive determination of life, but what how can we determine the absence of life on Mars (or any other planet for that matter)? We can look all over the planet and not find any specific indication of life, but we haven’t really proven that there’s not life- only that we haven’t found it. Even today biologists here on earth are finding microbial organisms in extreme environments that no one imagined could harbor life. These extremophiles demonstrate that life is far more tenacious than we really comprehend.
I suppose that one example from my own experience that occurs to me comes from hunting. This summer I spent several weeks hunting in the high Uintah mountains of Utah. I was fortunate to see many deer and elk during the time that I was there, but there were several days that I didn’t see anything (other than thousands of mosquitoes!). Despite not seeing these animals, I was pretty sure they were there- I just wasn’t very good at finding them. Hey, I never suggested that I’m a good hunter. Here’s the key though. Even though I didn’t see the animals I still behaved as if they were there, because I knew there was a chance that I might find one right behind the next tree.
So the question of planetary protection, in my opinion, isn’t so much about whether or not there’s life on Mars. If there is then we need to take precautions to protect that life. If we don’t find life we still need to assume that it may be present and proceed taking the same precautions to protect potential life. Either way, the end result is the same. In my opinion the argument is moot, and we should focus our energy on determining how we can progress in our exploration of Mars and other planets while still fulfilling our responsibility to protect life wherever we might find it.