When you get a letter from a legendary science fiction author, you stop and take notice. When the letter claims that NASA space probes have spotted enormous forests on Mars and requests an investigation, you really take notice, though maybe not the way the writer had in mind.
That happened to me a few years ago when I opened my email to find an earnest exposé from Arthur C. Clarke, author of 2001: A Space Odyssey. He included links to images from NASA’s Mars Global Surveyor (the most advanced Mars orbiter at the time), showing vistas that really did resemble thick stands of giant trees. Clarke died in 2008, but ever since, I’ve been keeping tabs on the visual oddities of the Red Planet — and there is no shortage of them. In the past few years, Mars fanatics have identified objects that look like rats, rabbits, lizards, even a mermaid sculpture. Clarke’s forests still have their fans, too.
Just to get the obvious out of the way: No, scientists are not hiding the discovery of life on Mars. Jim Bell of Arizona State University, one of the lead researchers running the Curiosity rover’s color camera, laughs off the notion that he might be part of a conspiracy. “My colleagues and I, we would be at the front of the parade if we discovered a dinosaur bone or a tiny lizard on Mars,” he says. “It would be the most spectacular discovery in the history of science. Why the hell would we cover it up? Come on!”
Bell also sees a serious side to those whimsical sightings. “The first impression I get from the Mars pictures is that the place looks familiar. Then I take a closer look and realize, wow, this place is fundamentally different. We see crazy protrusions and weirdly carved surfaces, almost Dr. Seuss-like — things that tend not to get preserved [permanently] on Earth,” he says. The juxtaposition of exotic-looking forms in an ordinary-looking setting gets the mind going, “and of course, as humans, we like to see faces and people and structures and geometric forms all over the place.”
Such perceptual biases (technically known as pareidolia) can be misleading, but for planetary scientists they are also quite useful. The eye’s tendency to latch onto visual oddities makes it a sensitive tool for picking out the most distinctive aspects of the Martian environment, the sights that stand apart from the terrestrial norm. “We are learning how to look at Mars like an alien geologist,” like a researcher native to the Red Planet, Bell says. Doing so reveals a planet that may not contain life but that has, in its way, a life of its own.