Has Life Been Found on Mars?

Steve Benner is one of the heavyweights of both theoretical and applied biology. A founder of the field of synthetic biology, he was the first person to synthesize a gene, and one of the originators of the Ribonucleic Acid (RNA) world theory of the origin of life.

Benner is also a successful biotech entrepreneur – a fact which is relevant because having an independent financial base has given him the ability to speak freely without regard to the NASA party line.

In his terrific new book, “Meet the Neighbors: Life on Mars and How to Find It,” Benner pulls no punches in drawing powerful conclusions based on both his own research and an encyclopedic knowledge of the work of the astrobiology community at large.

Assembling impressive evidence, Benner boldly argues that there is almost certainly life on Mars; furthermore, that life originated on the Red Planet before it appeared on Earth, and in all probability served as the source of life here.

In its statements supporting its various Mars missions, NASA’s public relations department always claims that their purpose is to search for life. They say this because they know that this is what the American people – quite rightly – are most interested in. Unfortunately, it is not true. In point of fact, NASA has not flown a life detection instrument to Mars since the Viking mission, which landed on the Red Planet July 20, 1976, almost exactly a half century ago.

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Since that time, NASA has flown six orbiters (four successful), four stationary landers (three successful), and five rovers and a helicopter (all successful) to Mars. But while these have gained some very useful data on the Martian environment (of which more later), none have tried to look for life itself.

So Benner starts with Viking.

Findings from Viking

The Viking mission landed two identical landers on Mars, at two widely separated low-altitude, mid-latitude locations. Each of the Viking landers carried three life detection experiments. Two of them looked for autotrophic life by testing whether Martian soil contained photosynthetic microbes that might either fix carbon or release oxygen, The other, known as the Labeled Release Experiment, tested to see if it contained microbes that might break down organic materials via a process such as respiration.

In the event, all three of the experiments on both landers yielded strongly positive results. As then director of NASA’s Goddard Institute for Space Studies Robert Jastrow said at the time “Short of seeing something wiggling at the end of a pin, the case for life on Mars is now as complete as the Viking experiments could make it.”

However, the Viking landers also carried a fourth instrument, known as a Gas Chromatograph Mass Spectrometer (GCMS) designed to assess the chemical composition of the soil, and it detected no organic material in Martian dirt. This came as quite a surprise, because even if there were no life on Mars, it was expected that some organics would be found, if from no other sources than meteorites, which frequently contain sturdy organic compounds known as polycyclic aromatic hydrocarbons (PAHs), which can survive impact. But not even these could be detected.

Rather than view the GCMS results as suspect, however, the conclusion drawn by Viking Science Team leader Gerald Soffen was “That’s the ballgame. No organics, no life.” While the Labeled Release Experiment principal investigator Gil Levin continued to insist that his device had in fact detected life, the other researchers all went along with the team conclusion and devised non-biological explanations for their results.

It was thus concluded that Viking had not found life on Mars.

Over the years this claim not only became gospel, but in textbook versions became exaggerated to say that Viking had shown that there was no life on Mars. Levin (who interestingly, as the owner of a water quality testing technology company, also was financially independent of NASA research grants) stuck to his guns until he died in 2021. As a result, however, he became regarded as a crank, and even had shrimp thrown at him when he stood up to speak at one conference dinner in his later years.

Benner was not directly involved in Viking, and as an outsider, initially accepted the community conclusion. But around the turn of the century, he began to suspect that something was amiss and took the trouble to dig out and read the original data reports.

There were a number of problems.

First of all, as Levin continued to point out, the GCMS was not sensitive enough to detect organics in the soil of Chile’s Atacama Desert, in which there certainly is microbial life, albeit in sparse concentrations. But more importantly, Benner discovered that the GCMS had in fact measured organics. Specifically, when tested in space on the way to Mars it detected freon gases, and on the surface of Mars it had detected methyl chloride emitted from samples of Martian soil.

Now freon gases are common refrigerants, and those detected in space were certainly contaminants originating on Earth. Methyl chloride, a simple molecule consisting of one carbon bound to three hydrogens and a chlorine, is a gas even at Martain ambient temperatures. Consequently, it can’t be native to Martian soil, because it would instantly evaporate.

The team therefore dismissed its presence in Martian soil sampled by the GCMS as experimental error, putting it down as a refrigerant contaminant, even though it is not used for any such purpose on Earth. But Benner began to wonder. Where could it have come from?

New evidence from the Phoenix Lander team

The answer started to become clear in 2007, when the Phoenix Lander science team led by University of Arizona Professor Peter Smith, detected perchlorates in Martian soil. These compounds are oxidizers, and while they are not strong enough to oxidize organic materials under normal Martian environmental conditions, Mars soil placed in the GCMS was heated up to high temperatures. In such a furnace, the perchlorates would have rapidly oxidized any Martian organics present in the spoil, including even tough PAH’s, procuring – among other products – methyl chloride.

With this mystery solved, the Viking GCMS results were completely discredited. The GCMS could not have detected organics because it destroyed them itself! So Soffen called the ballgame against the life detection experiments based on defective data. Not only that, but in 2020 we learned that organics are in fact present on Mars, when the Curiosity Rover detected them in large quantities in Martian mudstones.

That leaves us with all three life detection experiments on both landers reporting positive results, and no grounds for dismissal. The weight of evidence now stands with life.

Giordano Bruno was burned at the stake for arguing that there were other worlds orbiting other suns. We’ve progressed a lot since then. Levin only had shrimp thrown at him for making a comparable claim. Still, hats off to the true heroes of science.

But the question of whether there is life on Mars is only the start of Benner’s inquiry. The more important question is how it got there, or here for that matter.

Origins

There is evidence for the existence of life on Earth going back roughly four billion years. The Earth formed 4.5 billion years ago, and was too hot for liquid water for its first several hundred million years. So, life appeared here practically as soon as it could. This implies that either the processes that lead to the development of life from chemistry are highly probable, or that the seeds of life are floating in space and take root on any world as soon as it offers acceptable conditions. Either theory would imply that life is plentiful in the universe. But which one accounts for our ancestry? Benner opts for both.

In many ways, the early Earth and the early Mars were twins. Both were rocky planets with oceans of water, volcanic geology, and atmospheres consisting of mixtures of nitrogen and carbon dioxide. But Mars cooled first and thus had liquid water first. The Earth, however, had much more water – so much more that in its youthful days before geologic actions had lifted up continents, our planet was completely covered by a global ocean.

In contrast, being much drier, young Mars had both dry land and water. This relative impoverishment in water was a critical advantage for Mars as a cradle for life, Benner says, because it allowed small amounts of spontaneously created complex chemicals to be concentrated for further reaction in shrinking lakes or ponds. In contrast, Earth’s global ocean would dilute any interesting chemical novelties to insignificance.

Benner describes in some detail the processes necessary for the creation of the requisite chemical precursors for life, notably RNA, which he has actually duplicated under simulated early Mars conditions in his lab. To do it, water, the right kinds of rocks, atmospheric gases, and sunlight, all need to be available simultaneously all in the same place. That was true on the wet rocky Mars, but not on the ocean Earth.

There is natural transport of materials between Mars and Earth, caused by the impact of meteors that scatter rocks into space. This is still going on today. It is estimated that about 500 kilograms of Martian rocks land on Earth every year. Scientists have collected dozens of them, and on the basis of their studies it is clear that the processes involved in impact, flight through space, and re-entry and landing on Earth would, in many cases, not heat them sufficiently to sterilize them. During the solar system’s early period, there were a lot more impacts going on all the time, and the interplanetary rock traffic would have been much heavier. If life appeared on Mars before it did on Earth, it would have had no difficultly getting here.

In all probability then, life on Earth came from Mars. It’s probably still coming, but late coming Martian immigrants can’t survive here, because local conditions changed a lot since Earth’s early days. For one thing, photosynthetic organisms have radically changed the composition of Earth’s atmosphere, turning its CO2 into oxygen. This has caused the surviving descendants of the Earth’s earliest inhabitants, anerobic bacteria, to migrate deep underground where they can be sheltered from oxygen, which they find toxic.

So, science fiction films about killer plagues from space to the contrary, we shouldn’t fear finding life on Mars. If the Red Death could come here to infect our planet, it already would have done so, billions of times. Rather, we should seek Martian life to find fundamental truths about the laws of nature.

Scientists have traced back the evolution of life on Earth to the aforementioned anerobic bacteria, but not further. Yet as simple as they are, these microbes are actually incredibly complex organisms, involving all sorts of intricate molecular machinery. They could no more be the first life forms than an iPhone could be the first machine. There had to be more elementary life forms first. The fact that we find no such free-living simpler “prebacteria” on our world is yet another reason to suspect that life did not originate here.

But perhaps they can be found on Mars. Perhaps by going to Mars we can find not just other types of life, but earlier types of life. Certainly, if life has been on Mars for four billion years it will have had plenty of time to explore evolutionary options in novel directions not taken on Earth. This will tell us a lot about the range of possibilities available to life in the universe.

But on Earth, we generally find that even as evolution generates new and more complex forms of life, representatives of the simpler forms continue to persist. Can the prebacteria, or still simpler forms, still be found on Mars? If so, studying them could tell us a lot about not only the origin of life, but indeed the fundamental nature of life.

Is life on Earth a local oddity, or is it the local representative of a vast and incredibly varied cosmic phenomenon? What’s really going on in this universe of ours, anyway?

Let’s go to Mars and find out.