A scientist recently claimed that NASA may have inadvertently discovered life on Mars almost 50 years ago and then accidentally killed it before realizing what it was. But other experts are split on whether the new claims are a far-fetched fantasy or an intriguing possible explanation for some puzzling past experiments.
After landing on the Red Planet in 1976, NASA's Viking landers may have sampled tiny, dry-resistant life-forms hiding inside Martian rocks, Dirk Schulze-Makuch, an astrobiologist at Technical University Berlin, suggested in a June 27 article for Big Think.
If these extreme life-forms did and continue to exist, the experiments carried out by the landers may have killed them before they were identified, because the tests would have "overwhelmed these potential microbes," Schulze-Makuch wrote.
This is "a suggestion that some people surely will find provocative," Schulze-Makuch said. But similar microbes do live on Earth and could hypothetically live on the Red Planet, so they can't be discounted, he added.
However, other scientists believe the Viking results are far less ambiguous than Schulze-Makuch and others make them out to be.
Each of the Viking landers — Viking 1 and Viking 2 — carried out four experiments on Mars: the gas chromatograph mass spectrometer (GCMS) experiment, which looked for organic, or carbon-containing, compounds in Martian soil; the labeled release experiment, which tested for metabolism by adding radioactively traced nutrients to the soil; the pyrolytic release experiment, which tested for carbon fixation by potential photosynthetic organisms; and the gas exchange experiment, which tested for metabolism by monitoring how gases that are known to be key to life (such as oxygen, carbon dioxide and nitrogen) changed surrounding isolated soil samples.
The results of the Viking experiments were confusing, and have continued to perplex some scientists ever since. The labeled release and pyrolytic release experiments produced some results that supported the idea of life on Mars: In both experiments, small changes in the concentrations of some gases hinted that some sort of metabolism was taking place.
The GCMS also found some traces of chlorinated organic compounds, but at the time, mission scientists believed the compounds were contamination from cleaning products used on Earth. (Subsequent landers and rovers have since proved that these organic compounds occur naturally on Mars.)
However, the gas exchange experiment, which was deemed the most important of the four, produced a negative result, leading most scientists to eventually conclude that the Viking experiments did not detect Martian life.
And in 2007, NASA's Phoenix lander, the successor to the Viking landers, found traces of perchlorate — a chemical that's used in fireworks, road flares and explosives, and naturally occurs inside some rocks — on Mars.
The general scientific consensus is that the presence of perchlorate and its byproducts can adequately explain the gases detected in the original Viking results, which has essentially "resolved the Viking dilemma," Chris McKay, an astrobiologist at NASA's Ames Research Center in California, told Live Science in an email.
But Schulze-Makuch believes most of the experiments may have produced skewed results because they used too much water. (The labeled release, pyrolytic release and gas exchange experiments all involved adding water to the soil.)
Too much of a good thing
"Since Earth is a water planet, it seemed reasonable that adding water might coax life to show itself in the extremely dry Martian environment," Schulze-Makuch wrote. "In hindsight, it is possible that approach was too much of a good thing."
In very dry Earth environments, such as the Atacama Desert in Chile, there are extreme microbes that can thrive by hiding in hygroscopic rocks, which are extremely salty and draw in tiny amounts of water from the air surrounding them. These rocks are present on Mars, which does have some level of humidity that could hypothetically sustain such microbes. If these microbes also contained hydrogen peroxide, a chemical that is compatible with some life-forms on Earth, it would help them to further draw in moisture and also may have produced some of the gases detected in the labeled release experiment, Schulze-Makuch proposed.
But too much water can be deadly to these tiny organisms. In a 2018 study published in the journal Scientific Reports, researchers found that extreme floods in the Atacama Desert had killed up to 85% of indigenous microbes that could not adapt to wetter conditions.
Therefore, adding water to any potential microbes in the Viking soil samples may have been equivalent to stranding humans in the middle of an ocean: Both need water to survive, but in the wrong concentrations, it can be deadly to them, Schulze-Makuch wrote.
Alberto Fairén, an astrobiologist at Cornell University and co-author of the 2018 study, told Live Science in an email that he "totally agrees" that adding water to the Viking experiments could have killed potential hygroscopic microbes and given rise to Viking's contradictory results.
This is not the first time that scientists have proposed that the Viking experiments may have inadvertently killed Martian microbes. In 2018, another group of researchers proposed that when soil samples were heated up, an unexpected chemical reaction could have burned and killed any microbes living in the samples. This group claims that this could also explain some of the puzzling results from the experiments.
However, as McKay suggested, scientists who continue to chip away at the landers' results are wasting their efforts. "I disagree with their logic," he said. "There is no need to invoke a strange new type of life to explain the Viking results."
This article was provided by LiveScience.
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Harry is a U.K.-based staff writer at Live Science. He studied Marine Biology at the University of Exeter (Penryn campus) and after graduating started his own blog site "Marine Madness," which he continues to run with other ocean enthusiasts. He is also interested in evolution, climate change, robots, space exploration, environmental conservation and anything that's been fossilized. When not at work he can be found watching sci-fi films, playing old Pokemon games or running (probably slower than he'd like).
Good news for life: Mars rivers flowed for long stretches long ago, https://forums.space.com/threads/good-news-for-life-mars-rivers-flowed-for-long-stretches-long-ago.62274/Reply
Interesting how life on Mars reports keep popping up through the years :)
ET life is reported often because the first person to make a verified claim stands to become the most celebrated person in history since dirt. There is no downside for a false claim. False claims can feed forever on:Reply
"Shoulda' been here yesterday"
"Check's in the mail"
"Free beer tomorrow"
"Dog ate my pyrolytic mass spectrometer readout"
"Government is hiding the evidence"
"The sheer bulk of fake evidence should convince you"
"Open your eyes, Man!"
Did anyone ever suspect that Mars, is, the end result, of a 'flat-spin'-ing planet?Reply
What is a flat spinning planet?Reply
+1. Not sure to what this term refers to.billslugg said:What is a flat spinning planet?
Apparently "flat spinning planet" is a band aid to fix hydrostatic equilibrium problem with a large disc such as flat Earth. Large flat disc would quickly form a sphere, so they are saying "what if the disc rotates fast enough to maintain the disc shape?" For example: If the Earth spun just barely below the "fly apart" limit, it would be 3:1 diameter to thickness. Denser is better, pure uranium could get 5:1 before flying apart.Reply
The opriginal poster is suggesting Mars is a disc facing us and rotating fast enough to stay stable. Which we can see, by simple observation, it is not, so the answer would be "no", no one is considering Mars as a disc.
Getting back to the subject of the article, I don't see anything wrong with the logic that we may not have good proof that there was no life form present in the samples taken by the Viking probes.Reply
It would be interesting to see what the results would be for doing the same tests on the Atacama microbes. But, even that does not tell us what microbes might be like on Mars. If they exist, they are probably adapted to somewhat different chemistry and different temperatures than we expect for life on Earth. Wetting samples, heating samples, and any other disruptions of their actual natural environment should not be expected to produce the same effects as what we would see on Earth with microbes that evolved here.
There does seem to be sufficient energy sources and water to support some forms of extreme life on Mars, so the real question is whether life ever originated there and if it did, has it adapted well enough to still survive there now in at least some locations.
I don't think we can logically exclude the possibility without exploring a lot more of the potential habitats with a lot more sophisticated techniques. It would probably require a crewed mission and an extended stay to prove that life does not exist there now, and it would take a lot more to be confident that it had never gotten a start there.
On the other hand, it is logically possible to prove that is did occur there is we can find just one example.
In my post #2, I cited some of Charles Darwin letters and applied to life on Mars reporting. Charles Darwin acknowledged that life evolving from non-living matter, there was no worthwhile evidence for this in science as he clearly stated in his 1882 letter. Apply this standard to life on Mars or origin of life on Mars. IMO, no worthwhile evidence presented shows life on Mars today, yesterday or a trillion years ago or abiogenesis took place on Mars. This includes Bill Clinton Administration presser on ALH84001 meteorite back in the 1990s, one time looked like the best evidence but not around today as previously thought. I found Charles Darwin statements in his 1871 and 1882 letters, refreshing to read.Reply
We have learned a lot since Charles Darwin started guessing about the origins of life on Earth. I see no reason to limit myself to the thinking based only on the knowledge available in 1882.
Finding life on another planet would be a big step in our learning process, if that ever occurs.
Not finding life on Mars, even after a thorough search, would not completely settle the question, though. However, as we learn more about the very early conditions on both Earth and Mars, and see where life is able to exist in places like the Atacoma Desert and in solid rocks miles below Earth's surface, it seems as though Mars is a pretty good test for whether life on Earth is an extremely rare or a rather common situation.
At this point, we have neither found life on Mars nor ruled out the possibility that we will find life on Mars. If not by better examination of the materials that the Viking landers tested, then perhaps somewhere else on the planet.
Unclear Engineer, interesting thinking in your post #10. However, I am not limiting science to 1882 but pointing out Charles Darwin willingness to be objective and freely acknowledge the lack of evidence for abiogenesis in his days. The Mars life theme repeated over and over again to the public, lacks such a direct, and objective expression of the facts as Charles Darwin expressed in his letters.Reply