Conceptual image of NASA’s Mars 2020 rover. Image : NASA/JPL-Caltech

In a recent interview with the Telegraph, NASA chief scientist Jim Green said it’s possible we’ll soon find evidence of life on Mars but that “we’re not prepared for the results.” Green said the discovery would be as world-shaking as the revelation that the solar system doesn’t revolve around Earth. But while finding our first aliens would no doubt be amazing, it’s not a given that it would have any major impact on life on Earth.


Green was speaking to the Telegraph about upcoming missions to Mars, namely NASA’s yet-to-be named Mars 2020 rover and the ESA’s ExoMars rover, named the Rosalind Franklin, both of which could be roaming the surface of the Red Planet by 2021. In his comments, Green said a “real possibility” exists that one of these rovers, and possibly both, will detect traces of life . So confident is Green about this fantastic prospect that he’s already worried about having to break the news to the public, as he explained to the Telegraph:

“It will be revolutionary,” he said. “It’s like when Copernicus stated ‘no we go around the Sun’. Completely revolutionary. It will start a whole new line of thinking. I don’t think we’re prepared for the results. We’re not. “I’ve been worried about that because I think we’re close to finding it, and making some announcements.”


These are, needless to say, some rather big and bold claims. To be clear, there is currently no definitive evidence of life on Mars (whether extinct or extant), and there are no imminent announcements about the discovery of life on Mars. Just to be sure, we reached out to Green for further clarification.

“It’s incorrect to think that we have found life and that we are working toward an announcement,” Green wrote in an email to Gizmodo. “What we have are missions that we’re going to launch that will look for life.”

NASA chief scientist Jim Green. Image : NASA

Similar to the way “the human Moon landings changed our conception of our place in the universe, the discovery of life elsewhere would also be a civilization-changing event,” said Green.


But some experts we spoke to disagreed that finding alien life would truly change much on Earth.



“Well yes, maybe [we’re unprepared],” said Wieger Wamelink, a senior ecologist at Wageningen University & Research and an advisor to the MarsOne project, in an email to Gizmodo. But this “is mostly a philosophical issue that will have an impact, but not on day-to-day life,” he said. “The stock exchange will not react and countries will not go to war because of this.”


Steve Clifford, a senior scientist at the Planetary Science Institute, doesn’t think we’re unprepared for such a discovery, pointing to an episode 23 years ago as an important precedent.



“In 1996, scientists at the Johnson Space Center announced that they had discovered potential evidence of life in the Martian meteorite 84001,” Clifford wrote in an email to Gizmodo. “That announcement was widely covered in the media, and the public followed that announcement with great interest, but [there’s] little evidence that [it] provoked any widespread concern. I think that decades of rational scientific discussion about the likelihood that life is likely prevalent in the universe has helped prepare the way, should we discover unequivocal evidence of life on Mars or elsewhere.”


Conceptual image of ESA’s ExoMars rover, named the Rosalind Franklin. Image : ESA

Given that the potential for alien life to be found in our solar system has been a mainstream idea for decades, is it even accurate to say such a discovery would be revolutionary?




“I think news of life on Mars, if found, would be a big deal that would shake up people’s thinking about how rare or common life is in the cosmos,” Bethany Ehlmann, a research scientist at NASA Jet Propulsion Laboratory and a member of the NASA 2020 rover team, wrote to Gizmodo. “It would be awesome and thought-provoking, which is what I bet Dr. Green was trying to convey.”

“Yes, I think such a discovery would be momentous, more momentous than the Copernican Revolution, but philosophically very similar,” David Weintraub, a professor of astronomy at Vanderbilt University, told Gizmodo in an email. “Pre-Copernicus, most thinkers—whether for religious or philosophical or metaphysical reasons—accepted that Earth was the center of the universe and thus that we were likely the center of creation and of God’s attention... Copernicus de-centered humanity. The discovery of life beyond the Earth will, similarly, decenter humanity. Life on Earth would no longer be unique. Honestly, I can’t think of a more momentous discovery.”


Bruce Jakosky, a professor of geological sciences at the University of Colorado, agrees. Even though “we suspect that life could be widespread throughout the galaxy,” he said, “finding even one example of life off of the Earth would be a big deal.” That said, the discovery would have “no immediate consequences for anybody but us scientists who are working in that area” and it “wouldn’t change anybody’s day-to-day activities, but it would change our entire philosophical view of the universe.”

What about implications for religions? Would finding alien life cause a mass crisis of faith?


“Unfortunately, I’ve spent years working through these questions,” said Weintraub. “My 2014 book, Religions and Extraterrestrial Life, is devoted entirely to how religions of the world would react. The short answer is that some already believe in ET (e.g., Mormonism, Bahá’í ), some simply assume such life likely (Hinduism, Buddhism), some think that ET is God’s business, not ours (Judaism), and some (mostly conservative Christian denominations) would have big problems.”

Since certain religious groups already deny the veracity of dinosaur fossils, however, it’s not a stretch to imagine that they would also refute any evidence of alien life.


Finding life on a planet other than Earth would be momentous, even if that life is merely microbial. But a discovery on Mars—right in our backyard, relatively speaking—would carry even deeper implications. By finding a second habitable planet in our solar system (assuming it arose independently from life on Earth and is not the result of planet-on-planet contamination), our conceptions and expectations of pan-galactic habitability would have to undergo a complete revision. It would strongly suggest that our galaxy, and likely the entire cosmos, is exceptionally friendly to life (a so-called biophilic universe). So on this point, Green is absolutely right to say the discovery of life on Mars would be huge.


At the same time, however, a biophilic universe would further complicate the Fermi Paradox—the unanswered question as to why we haven’t seen signs of extraterrestrial intelligence. If life is ubiquitous, then where the hell are all the aliens?

That Mars once hosted life, or still does, is a fascinating theoretical possibility. But it’s not fair to say a discovery is all but certain, as Green’s comments to the Telegraph imply.


“Green saying we’re ‘close’ to finding [life on Mars] is him blowing smoke,” said Weintraub. “He doesn’t know anything you or I don’t know.... Will the Mars 2020 rover or the ExoMars rover find more robust evidence? Could happen. That’s what they’re designed to do. But saying we’re close to finding it is misleading and, I think, evidence of science—or scientific leadership—done poorly.”

Jakosky said we’re not necessarily close to finding life anywhere in the Solar System.




“We are making and will be making measurements that have the potential to show evidence of life, if there is life there,” Jakosky told Gizmodo in an email. “That’s very different from the implication in [Green’s] statement that we’re very close to finding life that we suspect or know is there. We’re going to Mars to find out if there is life there, not to find life that is there. This means that we might find evidence for life, we might find evidence that there is no life, or we might not be able to tell from the measurements.”

Importantly, Green is correct to assert a level of unpreparedness in the scientific community. It’s not immediately clear, for example, how we’d responsibly handle alien microbes, as NASA astronomer and science historian Steven J. Dick pointed out in Scientific American last year:

...the scary fact is that no guidance exists on what to do if microbial life is actually discovered. In the context of microbes, it matters whether we adopt an anthropocentric... ethic that confers intrinsic value only on reasoning beings, or a biocentric ethic that values all living things. It matters whether we consider microbes only of scientific value, or whether they are considered to have intrinsic value, in which case microbes have rights too—rights that we do not give their counterparts on Earth. Planetary contamination policies seem to confer rights on any microbes we may find on other worlds; the central goal of those policies, after all, is to protect from contamination any planets that might harbor life. That is a kind of biocentric ethic.




Wamelink doesn’t entirely agree with this assessment, saying protocols were in place during the Apollo program to sequester potentially dangerous microbes.

“Moreover, we do have strict protocols for bacteria and viruses on Earth,” he told Gizmodo. “These protocols are very strict and also in place at Wageningen University for [genetically modified organisms] and other bacteria. These protocols could easily be applied to alien lifeforms.”


“Of course we’re not fully prepared,” said David Grinspoon, a senior scientist at the Planetary Science Institute. “If we were, it would not even be an interesting discovery. How can you be fully prepared for something revolutionary? I don’t see why this is something to worry about. Rather it is something to anticipate with joy. We’re as prepared as we’ll ever be. Bring it on!”

On that note, here’s hoping for great success for NASA’s 2020 rover and the ESA’s Rosalind Franklin. May the quest for life on Mars continue, with tempered expectations.