The Curiosity rover touched down on Mars earlier this month with one primary mission: Find evidence that suggests there is or was life on Mars. So what happens if it succeeds?
President Obama has already said the discovery of life on Mars would instantly become one of the most important human discoveries. In a call with NASA scientists in charge of the Curiosity rover on Monday, he said, "I've got a lot of things on my plate, but if there is [life on Mars], I suspect that'll go to the top of my list."
It's highly unlikely Curiosity will actually discover life, because its cameras aren't powerful enough to actually observe microbes, explains NASA's Catharine Conley. But its instruments are designed to detect what are known as the "building blocks" of life—chemical compounds that could suggest life exists or once existed on Mars. If it does, scientists will have to decide what to do next.
Famous astronomer Carl Sagan once wrote, "If there is life on Mars, I believe we should do nothing with Mars. Mars then belongs to the Martians, even if the Martians are only microbes." It's a noble concept, says Robert Zubrin, president of the Mars Society, a group encouraging humans to explore the planet, but it's off base, he says.
"I think Sagan's statement is basically political correctness gone berserk. It's completely wrong. Ethics needs to be based on what's best for humanity, not what's best for bacteria," he says. He likens exploring Mars to Europeans exploring North America—if there weren't any Native Americans already on the continent.
"The destruction of the American Indian culture was a tragedy because they were people. They weren't bacteria. It demeans [the Native Americans] to compare them to that," he says. "I think Sagan's sentiments are misplaced, and they have no validity whatsoever."
Even if NASA agrees with Zubrin (and the fact that, until last year, a Mars sample return was planned for the future, it appears NASA does), the agency follows strict "planetary protection" guidelines when exploring the solar system.
According to a 1967 United Nations treaty, countries should "conduct exploration of [planets] so as to avoid their harmful contamination." That's why Mars rovers, including Curiosity, are carefully cleaned before being launched to avoid taking microbes from Earth into outer space.
NASA's Conley, who is head of the agency's Planetary Protection office, says exploration has to be done in a "controlled manner" to avoid "destroying stuff we will want later."
Contamination, she says, is a mistake that has been made over and over again on Earth as invasive species have taken hold in environments they aren't native too. The planetary protection guidelines are designed to avoid having the same thing happen in space.
Scientists have said that returning Martian soil to Earth should be the next interplanetary goal for humanity. But, if there are microbes living in that soil, humans run the risk of allowing alien life to take hold on Earth. The international community also has guidelines about how Martian soil should be stored on Earth.
"If you bring soil back to Earth, we have to contain it at the same level of security we use to contain things like the Ebola virus," she says. "We also have to make sure Earth life doesn't get into the samples."
The fact that man is still searching for life on Mars makes it unlikely that NASA will listen to Sagan's wishes and leave Mars to the hypothetical Martians. But Conley says that as soon as scientists think life might exist on the planet, the guidelines for what could visit the red planet would be tightened—any probes or rovers would have to be cleaned even better than they currently are, she says.
"We try to do full sterilization, but I'll tell you, it's not perfect," she says. "If we have evidence that argues there's life on Mars, we don't contaminate it until we have the chance to do science on it first."
Zubrin says that years after his statement, were he still alive, Sagan's tune might have changed.