In 1996, a team of scientists at Johnson Space Center, and Stanford University found a meteorite that suggested that primitive life existed on Mars more than 3.6 billion years ago! A time when Mars was warmer and wetter than present day Mars. Huge news that went somewhat unnoticed and partially because a poll of 100 scientists conducted by the University of Arizona found that although most scientists were open to the claims of “Life on Mars”, they remained unconvinced because they are trained to be skeptical. The type of microbe the study claimed to have found – cyanobacteria – are complicated because they live in liquid water and are photosynthetic. That is, they convert carbon dioxide into organic compounds using energy from sunlight – a complicated process that needed more proof than appearance. Basically, scientists were intrigued but wanted more proof about the entire process.
“Because this would be a very important result if true, scientists are going to do what they should do: be skeptical,” said astronomer Seth Shostak of the Search for Extraterrestrial Intelligence (SETI) Institute in Mountain View, Calif.
Shostak called the paper “an extensive and thorough review” of Hoover’s findings, but said they did not amount to convincing evidence.
“If you look at the microscope photos, they are certainly suggestive – looking like photos made of various terrestrial bacteria,” Shostak said. “But then again, while intriguing, that’s hardly proof. If similarity in appearance were all it took to prove similarity in kind, then it would be pretty easy for me to demonstrate that there are big animals living in the sky, because I see clouds that look like them.”
The meteorite, called ALH84001, is an igneous rock that weighs 4.2-pound, potato-sized meteorite that has been age-dated to about 4.5 billion years. Which dates back to the period when the planet Mars first formed. The rock is believed to have originated underneath the Martian surface and later forced to the surface. The team discovered the existence of microscopic magnetite crystals that the researchers said bore remarkable similarities to ones created by microbes on Earth. These types of magnetite particles are not known to be produced by nonbiological (abiotic) processes which the study team members said these crystals suggest they are evidence of the oldest life-forms known, with profound implications for the presence of life in the universe.
However, doubters such as such as Chris McKay, a planetary scientist at NASA Ames Research Center in Moffett Field point out the following. “”At the time of the ALH 84001 announcement, there was no known abiotic process that could produce such magnetite crystals. However, he noted that subsequent research has shown that shockwaves can generate such magnetite crystals. This weakened the case that ALH 84001’s crystals were created by life, he said.
It was a two-year investigation that wasn’t base on a single finding. In fact, a huge cache of Meteorites have been cataloged by NASA and is available on their Mars Meteorites page.
“There is not any one finding that leads us to believe that this is evidence of past life on Mars. Rather, it is a combination of many things that we have found,” McKay said. “They include Stanford’s detection of an apparently unique pattern of organic molecules, carbon compounds that are the basis of life. We also found several unusual mineral phases that are known products of primitive microscopic organisms on Earth. Structures that could be microscopic fossils seem to support all of this. The relationship of all of these things in terms of location – within a few hundred-thousandths of an inch of one another – is the most compelling evidence.”
“It is very difficult to prove life existed 3.6 billion years ago on Earth, let alone on Mars,” Zare said. “The existing standard of proof, which we think we have met, includes having an accurately dated sample that contains native microfossils, mineralogical features characteristic of life, and evidence of complex organic chemistry.”
“For two years, we have applied state-of-the-art technology to perform these analyses, and we believe we have found quite reasonable evidence of past life on Mars,” Gibson added. “We don’t claim that we have conclusively proven it. We are putting this evidence out to the scientific community for other investigators to verify, enhance, attack — disprove if they can — as part of the scientific process. Then, within a year or two, we hope to resolve the question one way or the other.”
“What we have found to be the most reasonable interpretation is of such radical nature that it will only be accepted or rejected after other groups either confirm our findings or overturn them,” McKay added.
The NASA-funded team found the first organic molecules thought to be of Martian origin; several minerals features characteristic of biological activity; and possible microscopic fossils of primitive, bacteria-like organisms inside of an ancient Martian rock that fell to Earth as a meteorite. This array of indirect evidence of past life will be reported in the August 16 issue of the journal Science, presenting the investigation to the scientific community at large for further study.
The two-year investigation was co-led by JSC planetary scientists Dr. David McKay, Dr. Everett Gibson and Kathie Thomas-Keprta of Lockheed-Martin, with the major collaboration of a Stanford team headed by Professor of Chemistry Dr. Richard Zare, as well as six other NASA and university research partners.
Donald L. Savage Headquarters, Washington, DC August 7, 1996 (Phone: 202/358-1727) James Hartsfield Johnson Space Center, Houston, TX (Phone: 713/483-5111) David Salisbury Stanford University, Palo Alto, CA (Phone: 415/723-2558) RELEASE: 96-160