NASA Curiosity rover on the Red Planet since August 2012 and the assessment of the habitability of Mars.
Finding evidence for life on Mars has been a decades-long ambition for NASA, which has billions of dollars to send, machines, rolling, poking and probing the Red Planet. But as soon as the signs of life are found, how are these findings being verified?
In the beginning of January, NASA’s Curiosity Mars rover came what some researchers thought might be trace fossils on Mars. Researchers first spotted in eye-catching, small, stick-like features in the black-and-white images, but they were interesting and unusual enough for the rover science team to roll the robot back to continue to ask questions.
A strictly mineral origin was considered to be the most plausible. Still, for some, the functions are presented in bioturbation, a process in which the living organisms in the sediment can disrupt the structure of these sediments. The features looked similar to Ordovician trace fossils here on Earth, arising from an age of more than 440 million years ago. [12 Possible Reasons why We Haven’t Found Aliens]
With respect to trace fossils on Mars, “We don’t rule,” Ashwin Vasavada of NASA’s Jet Propulsion Laboratory in Pasadena, California, and the project scientist for the Curiosity Mars rover, told Space.com. “But we will be sure not to jump to that if our first interpretation.”
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The event underlines the extent of difficulty in study and analysis of such specific properties, as well as the limits of the robots carried out “Curiosity science investigations” (CSI). But it also raises a fundamental question.
No doubt, Mars holds her secrets tight, but as the work of the tracing of the life proves the positive, what the protocols are in place to confirm that such a verdict?
Ladder of life
“It’s been a long time since we have visited, the procedure for the existence of extraterrestrial life announcements,” said NASA’s Michael Meyer, program scientist for the Mars Science Laboratory, and a scientist for the space agency’s Mars Exploration Program in Washington, D. C.
“My suspicion is that the adoption and publication would go our chain-of-command, more than likely goes all the way to the President,” Meyer told Space.com in an e-mail. “The perceived speed with which the finding would go viral changes only the immediacy of the response. In some ways … not too different of a spacecraft failure.”
Jim Green, NASA Planetary Science Division director, said organizing the thinking and approaches of the subject of the direct detection of life elsewhere, NASA and the astrobiology community have made of what is tagged as the “Ladder of Life Detection.” The ladder categorizes characteristics that indicate life, ordered from most to least indicative of the life, and how they can be discovered.
Green told Space.com that while the life-detection tools have limitations, the tools of today are on the different steps on the ladder. “The current systems can give us clues that tell us what to do as we climb on the Ladder of Life,” he said.
The possibility of a comprehensive set of measurements to detect life or past life on Mars is a complex, evolving process, Green said, it requires a systematic approach. “So that’s where we are. We have the methodology, I think, to continue to move in that direction.” [Missions to Mars: A Robot Red Planet Invasion History (Infographic)]
Everett Gibson, an emeritus scientist of the NASA Johnson Space Center in Houston, Texas, was co-leader of the team that announced in 1996 that he had discovered that the possible signatures of past life in ALH84001, a Mars meteorite fell on the Earth. A few years later, the team said that additional evidence in three Martian monsters strengthened her case.
The claims about ALH84001 were hotly debated, with the wider scientific community to point out the non-biological causes of the unusual features detected within the meteorite. The debate about the possible evidence of life in the Mars rock, however, is seen by many as a major event that helped in the field of astrobiology. Gibson is also the recent Curiosity photos interesting and is eager to learn of the composition of the functions in the picture. “They remind me of the things that we have observed in the terrestrial geological record of the Earth … but these features are on Mars,” he told Space.com.
“At least the JPL Curiosity team had enough interest to go back and obtain additional information about these features,” Gibson said. “Now, if [only] they would do compositional measurements on the features and the matrix of where they live,” he said.
An analysis by Curiosity’s Sample Analysis at Mars (SAM) instrument “would also be nice to search remaining biochemical-related compounds that may the functions” Gibson said.
While the data from SAM would have been, it was not used for the study of the strange features on Mars. (SAM is able to study powdered rock and regolith drilling samples.)
“We did not get the chance to taste this interesting features with SAM,” said Paul Mahaffy, principal investigator for SAM at NASA’s Goddard Space Flight Center. The Curiosity rover, Mars has been done to resolve the work on the curiosity rover’s drill recently, he told Space.com that excluded drilling for a few months.
Interpretations of data
About the search for life on Mars, Gibson remains confident about his team’s meteorite ALH84001 analysis and claims, which are now more than 20 years old.
“We still stand by our 1996, in the journal Science, and none of our data is refuted … only interpretations of the data,” Gibson said.
“It is clear that early in Mars in the first billion years, conditions were suitable for biogeochemical processes related to living systems to have operated. Now we wait for the further details of Curiosity and the team,” Gibson said.
Even as slam-dunk evidence of life on Mars, how would it be announced? And is there a process for checking the claims for that important announcement? “Not that I know of,” astrobiologist John Rummel, senior scientist at the SETI Institute and former head of NASA’s Planetary Protection Office, told Space.com.
“I would expect that the smart thing to do would be to review the evidence, in private, with a panel of experts who have a good understanding of the evidence examined and then moved to the right place from there,” Rummel said.
That group of experts, Rummel said, would have to struggle with a number of important questions such as: What evidence can be used as a confirmation of such a finding? What are the possible false-positive indicators that can lead us to mis-identify the evidence we see? [How NASA Could Look for Ancient Life on Mars (Infographic)]
To confirm the interpretation
Rummel recalls that with ALH84001, several researchers were able to examine the meteorite itself, but also the provision of expertise with regard to the evidence that is collected by the NASA Johnson Space Center team.
“I would say, if one is faced with provocative evidence of a possible “find” of ancient life on Mars,” Rummel said: “the first consideration would be to confirm that the interpretation of the evidence already gained, and to the conduct of other tests that can support or refute that interpretation.”
If one looks at morphological evidence — evidence on the basis of structures on Mars — Rummel said that chemical analyses need to be conducted to see if the results are consistent with the interpretation of the morphology. “The authentication of the data in as many different ways as possible is good,” he said.
That idea is shared by Bruce Jakosky, professor of geological sciences and associate director for science at the University of Colorado’s Laboratory for Atmospheric and Space Physics. He is also the principal investigator for the MAVEN mission now orbiting Mars.
Jakosky said that Curiosity is the most recent find is very different from the ALH84001 situation.
“In the case of ALH84001, the original researchers have a huge amount of analysis for the public, for defining the characteristics of what they saw and compare it with several different hypotheses of how they would be able to form,” said Jakosky Space.com. “They put their best hypothesis discussed why the biological and nonbiological mechanisms for the formation of may be possible, and reach their best conclusion. She recognized the uncertainties in their conclusion as well,” he said.
In the case of Curiosity, finding odd jobs, “until now we have is a single set of images, with no additional in-situ analysis of what is present and no in-depth comparison against competing hypotheses,” Jakosky said.
Speculation about the question of whether these characteristics may be biological “is what be premature,” Jakosky said. “While it may be that a biological origin is possible, science is about determining what the most likely and not only what is possible.”
If something is found, that appears organic, Jakosky suspect that such a conclusion would not be presented in a big press conference where the discoverers announce that the life has found.
“The most likely scenario is that the multiple analyses by different researchers, and that a consensus will be built up over time as the non-organic scenarios are either excluded or deemed to be less likely,” Jakosky closed.
Leonard David is the author of “Mars: Our Future on the Red Planet”, published by National Geographic. The book is a supplement to the National Geographic Channel series “Mars.” An old writer for Space.com David has been reporting on the space industry for more than five decades. Follow us @Spacedotcom, Facebook and Google+. This version of this story is posted on Space.com.