So far, we’ve seen a human face on Mars, a monster crab, and a cannonball.
At least that’s what the internet tells us.
It’s easy for people to look at images from the red planet and see all sorts of things that seem to indicate alien life—even though the truth is much less exciting. The human face is a mesa, the crab is just a rock, and the cannonball is a pebble.
Most scientists aren’t surprised when some people come up with a sci-fi explanation for an image from another planet. After all, humans evolved to find recognizable patterns amid chaos. There’s even a word for it: pareidolia. But what we don’t expect is for fellow scientists—those who have been trained in the scientific method—to make those claims. When they do, it hurts science as a whole.
For example, an Ohio University researcher recently presented a poster at a research conference claiming to have discovered evidence of beetlelike bugs on Mars.* The examples were blurry, ambiguous features in publicly released rover images. A significant social-media storm ensued and several stories in the press cried foul.
In addition, in a Scientific American essay, a scientist recently wrote that evidence of life has already been found on the red planet, based on his interpretations of the Labeled Release experiment on the Mars Viking lander mission. I and others argue that the results from the Viking mission have been examined in great detail and that no evidence exists to make a claim of life. The scientific community largely rejects his assertions, yet continue to receive attention.
Inevitably, when I discuss my skepticism, I’m called a naysayer and accused of being uninterested in finding life on other planets. Nothing could be further from the truth.
I want to find extraterrestrial life. It’s one of the things that drove me to study planetary science in the first place. And I’m not alone. Researchers all over the world are working every day to find signs of life. But, as Carl Sagan so sagely stated, “Extraordinary claims require extraordinary evidence.” And, as of now, the credible evidence based on rigorous application of the scientific method is just not there.
But we still have a lot to be excited about. Thanks to a long record of peer-reviewed research, we now know that billions of years ago, Mars had plentiful water that pooled in long-lasting lakes and streams. Organic molecules have also been identified in rocks and the atmosphere, and all of the elements known to be critical for life on Earth have been observed.
Just last month, a new paper revealed that variations in atmospheric oxygen abundance have been recently observed at the surface of Mars. This is incredibly exciting—particularly when you consider that oxygen is more plentiful in the southern hemisphere during spring. What does it mean? While we’re not yet sure, more research might tell us. But it’s critical that we carefully consider all of the possibilities, not just the most exciting ones.
In July, the Mars 2020 rover will launch with a host of sophisticated instruments aboard. I’m a member of the SuperCam team, an instrument suite developed at Los Alamos National Laboratory that will zap rocks with a laser to determine their composition and search for telltale signatures of life.
The rover also carries a drill that will gather rock and soil samples to be cached so a future mission can retrieve them and bring them back to Earth. Imagine what we will learn when we bring a little piece of Mars back and can bring our gold-standard laboratory measurement techniques to bear on these samples, not just the ones on the rover. The scientific community will no doubt be on the edge of their collective seats when that happens.
All of this is to say: We shouldn’t stop asking whether life existed (or exists) on Mars and working hard to find the answer. But we can’t make grand claims before we have solid proof from multiple observations.
One only needs to read the headlines today to know that great distrust of science and scientists abounds. That means the scientific community has an even greater responsibility to make sure that, when we present results to the public, they are scientifically sound. Bogus claims do not help either the public or the scientific community; in fact, they hurt it. Our job is to keep asking important questions, testing hypotheses to answer those questions, challenging each other on our findings, and improving our methods before trying again. That’s how scientific discovery works.
And if we do someday find proof of life on Mars, you can be sure that I will celebrate.
*Editor’s Note (1/14/20): This sentence was edited after posting to correct the affiliation of the cited researcher.