A new study, whose findings have been widely reported including by British tabloids such The Daily Mail and The Daily Express, claims to have found “evidence” — photographs that are supposedly of mushrooms — to support the hypothesis that life exists on Mars.
It has led to interest because the photographs were taken by NASA rovers Curiosity and Opportunity. However, it has also been met with skepticism, and the paper itself concedes that the evidence is not proof.
Life on Mars? The claim
The study has been published in Journal of Astrobiology and Space Science. The five researchers include a microbiologist with Pondicherry University, Regina S Dass, while the other four are with institutions in the US and Italy. It looks at various kinds of “evidence”, including simulation studies on what species can survive in a Mars-like environment, besides the specimens that resemble fungi, “puffballs”, algae and lichens.
The study also proposes Earth as an “obvious source” of life on Mars. Citing previous studies, it states: “It is probable that solar winds striking, ejecting and propelling microbe-laden dust and debris in the stratosphere and mesosphere, deep into space… and microbes dwelling in rock ricocheted into space from Earth by meteor strikes, have repeatedly contaminated Mars and other planets… and vice versa.” Even spacecraft may have carried fungi or microorganisms to Mars, it suggests.
The paper states that 70 scientists, on invitation, judged the probability of the objects in the NASA images being lifeforms. It claims that a significant majority agreed “there is a high probability fungi and lichens may have colonized the Red Planet”.
Life on Mars: Proof?
The paper states: “Nevertheless, much of the evidence remains circumstantial and unverified, and the possibility of life on Mars remains an open question.” At another point, it states: “Similarity in morphology, however, is not proof.” Of six scientists and eight scientists who reviewed the paper, three rejected it.
Yet the paper argues that the evidence in total weighs in favour of biology.
In an article questioning the paper, the science news portal Science Alert referred to comments by various Reddit users, NASA’s own previous findings on these objects, and remarks by the researchers themselves. One Reddit user, Zeeblecroid, wrote: “There’s a community of self-proclaimed astrobiologists who use the same crackpot tricks (mostly misrepresenting mundane photos of basic geological features as hard evidence of life) and have been for decades.”
Science Alert refers to a NASA post in which the space agency describes such objects, discovered in 2004, as “blueberries” and concludes after analysis that they were composed of the iron oxide, hematite. NASA itself hadn’t responded to the new claims until the weekend.
Science Alert also quotes Regina Dass as saying: “We admit we don’t have a smoking gun. No photos of cells or cellular structure. There is no definitive proof, only a lot of evidence which shouts: Biology.”