Lee Billings in Seed:
Seed: Why did you write this book?
Dirk Schulze-Makuch: The evidence for life on Mars has recently been portrayed over-skeptically and negatively. As a scientist you have to be skeptical, but here we have many strong lines of evidence for microbial life, and if you put them all together you really have a very consistent picture. So my coauthor, David Darling, and I both feel very strongly that we really have to get the public very enthusiastic about this, in order for space agencies to move forward.
Seed: But scientists also make names for themselves by overturning flawed conclusions. If the evidence is so good, why aren’t more researchers lining up to say there’s life on Mars?
DS: Well, it depends on what kind of group you’re looking at. If you ask the public, they seem to think there’s life on Mars—at least microbial life. I don’t want to speak for all scientists, of course, but I think among those who are knowledgeable there’s also a tendency toward thinking life is there as well. This is especially true for those researchers who study extremophiles, Earthly microorganisms that flourish in extreme environments. Some planetary scientists are still quite skeptical.
Seed: Your argument seems to hinge, in large part, on the results from the Viking landers. Could you summarize why these results point to life?
DS: In some ways the timing was bad for Viking. A lot of progress was made after its life-detection experiments were already on or on their way to Mars: The discovery of all the ecosystems at undersea hydrothermal vents, and the extremophile research of the early 1980s really changed how we think about life and its limitations. The Viking researchers thought life on Mars would be heterotrophic, feeding off abundant organic compounds distributed everywhere all over the Martian surface. That picture was wrong, and studies of extremophiles on Earth have made us think differently about Mars.