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Three Martian meteorites triple evidence for Mars life BY CRAIG COVAULT SPACEFLIGHT NOW Posted: January 9, 2010 
The team that found evidence of Martian life in a meteorite that landed in Antarctica believes that during 2010, by using advanced instrumentation on now three Martian meteorites, it will be able to definitively prove whether such features are truly fossils of alien life on the Red Planet. This new information goes well beyond the updated findings released by NASA in November 2009 about signatures for magnetic type bacteria. "We do not yet believe that we have rigorously proven there is [or was ] life on Mars." says David S. McKay, chief of astrobiology at the NASA Johnson Space Center. "But we do believe that we are very, very close to proving there is or has been life there," McKay tells Spaceflight Now.
And in a 2009 editorial, The Economist, a highly regarded British publication, also noted the explosion of both public and scientific interest in Mars saying "the possibility of life on Mars is too thrilling for mankind to ignore." In the mid-1990s, when the JSC team found what it interprets as Martian fossils inside a meteorite that landed near Allen Hills in Antarctica, it was the only example at the time of suspected fossils in a meteorite from Mars. The team, however, believes it has since tripled its fossil-like data
by finding more "biomorphs" (suspected Martian fossils) inside two
additional Martian meteorites, as well as more evidence at other spots
in the Allen Hills meteorite itself.
Had British researchers examined their "Nakhla" meteorite with readily available electron microscopes and other tools like those used by the U.S. team, the new evidence for life on Mars could have been a British discovery, rather than an American one. The Houston-based scientists believe the age spread of their data, from 3.6 billion to 1.4 billion years ago, shows that a planet-wide network of micro-organisms came to life underground on Mars 3.6 billion years ago during the first billion years after Mars had formed along with the rest of the planets in the solar system. Mars was much warmer and wetter with a much thicker atmosphere then. Simple life forms were beginning to form on Earth at about the same time. Scientists are able to tell that the meteorites came from Mars by measuring the noble gases trapped in the rocks and also by their geologic character. The noble gas ratios measured to determine Martian origin are helium, neon, argon, krypton, xenon and radon. The twin Viking landers of the mid-1970s measured Martian surface gas compositions in great detail, and the now more than 80 meteorites have been found and designated as being from Mars. They all have internal gas compositions that match the Viking lander data, as well as Mars rock compositions measured by spacecraft at the planet. "Similar biological type findings in three different meteorites that also correlate well with ancient Earth organisms considerably broaden the evidence for at least past life on Mars," says geologist Everett K. Gibson, co-leader with McKay and Kathie Thomas-Keprta on the JSC Mars life study team. According to the JSC team, the three Martian meteorites with the apparent fossil signatures include what appear to be mats of bacteria and specific other biological signatures that are common to all three meteorites.
In its November update, the Mars team said that for more than a decade after the Martian meteorite data were first presented in 1996, opponents of the life theory argued that fossil-shaped features and associated chemical purity was just as likely caused by the thermal/shock event that blasted the material off Mars in the first place. But new research led by Thomas-Keprta of the Allen Hills team in Houston has now proven the thermal theory is invalid. She says that finding strengthens the team's argument that uniquely-shaped "magnetic bacteria" features found in the meteorite were indeed formed by biologic activity on Mars and not some non-biologic thermal event. The new information from the team here goes well beyond the magnetic bacteria that dominated the NASA November release. McKay and co-leader of the Mars life team, JSC geologist Everett K. Gibson, have since provided Spaceflight Now with much more detail on two other major areas that will be the focus of more verification work starting this year. Noted astronomer the late Carl Sagan often said "extraordinary claims require extraordinary evidence," and the Johnson Space Center Mars life team believe they now have, or by year's end will have, such evidence. The two new areas involve: The Microprobe system will fire a focused stream of ions onto the biomorph/micro-fossil samples. The ions will flash the sample into plasma containing multiple constituents. A powerful spectrometer will then suck that in and out the other side read out constituents of each sample down to parts per billion level for each chemical or mineral constituent. Those ratios will then be used to determine whether the feature has its origin in non-living Martian geology or something biologic that was previously life on Mars. The new ion microprobe system should also provide the team with even higher optical resolution than the electron microscopes they have been using while also adding a major new chemical analysis dimension, says McKay. The team calculates that the Allen Hills meteorite is made of 4-billion-year-old Martian rock carrying fossil evidence of life dating back to 3.6 billion years. This is an extremely old sample not comparable to anything on Earth today because all of Earth's crust has been processed and reprocessed as part of Earth's plate tectonics. The sample is already proving the presence of water on Mars back to its early days as a planet. If the fossil evidence is confirmed, it will prove that organisms existed on the planet within about 1 billion years of its formation. After the initial Allen Hills announcement made in 1996 with President Bill Clinton, the Houston team began to search for similar life examples in other meteorites from Mars. And they found that evidence in the already famous Nakhla meteorite that fell near the town of Nakhla, Egypt, in 1911. Nakhla fell in about 40 pieces weighing about 20 lb. total. The largest sample set from that meteorite has been in the British Natural History Museum in London and virtually all of several pieces of Nakhla, which put on a spectacular show of flaming debris, smoke trails and sonic booms when it arrived at about 9 a.m. local time in the Nakhla region of Egypt south of Cairo. A local farmer claimed that one piece struck and killed a dog. But scientists believe the story was dreamed up by the land owner at the time seeking to boost prices for buyers seeking to purchase pieces. Then in 2000 a Japanese search team found another meteorite from Mars in Antarctica. It is designated Yamato 593 and also contains signs of fossil life similar to that seen in the Allen Hills and Nakhla meteorites. Both the Nakhla and Yamato life forms date to only about 1.4 billion years old, if it can be proved more definitively.
Answering whether life, even single-celled organisms, formed on another planet is one of the most profound questions in modern science, especially if the answer is positive. If that can be verified soon, it will also play a major role in Mars space mission operational decisions and the formation of new exploration policy by NASA and the White House. Examples are: "Even though we do not think the Endeavour crater is where these meteorites came from on Mars, any information that Opportunity could provide on the layering of similar carbonate rocks would be very useful to us," said Gibson.
Analysis of the Allen Hills, Nakhla and Yamato meteorites show the rock was blasted from depths as shallow as one-half mile and as deep as four miles. This puts them directly in the subsurface water table of Mars, Gibson said. Maria Zuber, who heads MIT's Department of Earth, Atmospheric and Planetary Science addressed the latest Mars water data this week at the American Astronomical Society meeting in Washington, D.C. "Recent observations of Mars from orbiting and landed spacecraft have dramatically changed our understanding of the distribution and amount of water at and beneath the surface throughout the planet's history," says Zuber. "There is definitive evidence for a watery past, including standing water on the surface, during Mars' early history, and the details of the global hydrological cycle, groundwater upwelling and aqueous chemistry have been elucidated. "There is evidence that much past surface water is currently stored in the upper crust in the planet's impact-generated regolith," she says. "And present-day Mars contains abundant water ice within a meter of the surface," says Zuber. The "biomorph" features discovered in the Yamato 593 meteorite look identical to those found inside the Allen Hills and Nakhla meteorites says McKay. Those Martian samples are also contained along with a mineral substrate called Iddingsite. In such material, the presence of carbonate is a giveaway for what on Mars would have been an underground aquifer with substantial water to generate this type of sample, McKay tells Spaceflight Now. The Iddingsite deposits continue to form and change the longer water flows through the rock providing additional evidence about the life forms that create tiny biomorphs -- the early stage for fossils that are most abundant with Iddingsite. Not only is there now abundant evidence for underground Mars life, the Japanese Yamato and Egyptian Nakhla samples, as well as increased samples of apparent fossils, look identical to samples in the Allen Hills meteorite.
And all of them look very similar or identical to the Earth fossil life examples found in Columbia River basalts in Washington State. The Martian samples have been recovered from Martian depths ranging from an estimated one-half mile below the surface to as much as about 4 miles deep. Allen Hills team members tell Spaceflight Now that this is especially fortuitous because many assessments about where Mars life would most likely survive is underground, out of reach from solar radiation and where aquifers most likely exist to hold life-giving water. This is also because those depths match assessments on where the underground Martian water table would have been the most active. Many Mars Reconnaissance Orbiter and Mars Global Surveyor images show what appear to be discharges of water from canyon and crater walls. That data was summarized initially before the Society of Photo-Optical Instrumentation Engineers. NASA rolled out the findings again in greater depth before the American Geophysical Union Meeting last week in San Francisco. That meeting was attended by 16,000 international scientists and managers who work in the field of geology, geophysics and other exploration related fields. Some of the data described here was prepared by McKay initially for presentation to the Society of Photo-Optical Instrumentation Engineers. "The biomorphs in these last two meteorites are nearly identical, supporting our hypothesis that they formed on Mars," McKay told Spaceflight Now. He also noted that the similarity of the biomorph features across the three main Mars meteorite samples also argues against contamination by material that instead may have formed on Earth. And Nakhla also scores big when it comes to "following the carbon." "We see considerable carbon in Nakhla," says McKay. He cited the work of University of Arizona geoscientist Dr. A.J. Timothy Jull, who has shown that at least 70 percent of the carbon in Nakhla is not from Earth but had to come from Mars. The new Martian life evidence has come to light just as President Barack Obama is examining increased funding for NASA. That federal budget decision is being made in the wake of presidential review commission findings that the agency needs at least $3 billion more annually to develop new launchers and spacecraft that would both replace the space shuttle and send astronauts beyond Earth orbit with Mars the ultimate destination before mid-century. That Mars is the ultimate destination is pretty clear in the report by a team headed by Norm Augustine, former CEO of Lockheed Martin. But how to go about it remains the bigger unanswered question. Independent researchers in New Mexico and Hawaii say images and geochemical data from MRO and the European Space Agency Mars Express orbiter indicate that the Allen Hills meteorite was blasted out of the southern end of the vast Valles Marineris in a canyon at a junction called Eos Chasma. In a striking coincidence, this location believed the source for the first meteorite found to carry evidence of Mars life to Earth is fed directly by a channel named after the late "Orson Welles." In 1938 he panicked the entire U.S. with his Halloween radio news bulletin broadcast of H.G. Wells fiction "War of the Worlds" about the first Martian landing in New Jersey. This is the second of a pair of articles updating the analysis of evidence for life on Mars carried to Earth in meteorites. The first appeared in Spaceflight Now on Nov. 24, 2009. |
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