Mars Meteorite home page of JPL
Johnson Space Center's 'Life on Mars?'
Ames Research Center's 'Life on Mars?' (mirror site)
Gordon Space Flight Center's 'Life on Mars?' (mirror site)
Research article in Science
Seach for past life on Mars (Research article in Science, mirror site)
Martian life page of FAS
News from SEDS
Special feature on CNN
Mars news from AUFORA
NASA's NewsRoom today
August 8, 1996
By David Colton
GANNETT NEWS SERVICE
WASHINGTON - On the morning after they said there might have been life on Mars, the man who predicted it a half-century ago answered every phone call with a groan.
"Here we go. I suppose this is about Mars again," snarled Ray Bradbury, author of "The Martian Chronicles," a book describing a lush but dying red planet peopled by changelings. Now 75 and living in Los Angeles, prophet had turned skeptic.
"I hope it's true with all my heart, but this is nonsense. There's just no proof," Bradbury said. "Ted Koppel called last night and asked me to be on `Nightline,' but I refused because I didn't want to be a grouch."
When the visionary isn't yet convinced, what chance do mere dreamers have?
It may be that the question of life on Mars, even if it was 3.6 billion years ago, is so cosmic, so in humanity's tribal face, that any answer in the affirmative must be for certain. It would, after all, change everything.
"If the results are verified, it is a turning point in human history," offered scientist Carl Sagan. At the age of 61, battling a blood condition in Seattle, Sagan's voice resonated with wonder for "the tantalizing prospect of a universe burgeoning with life."
Compared with the aliens of "Independence Day" and the like, "many people would consider this pretty small potatoes," Sagan said of the microscopic worm shells clutching the underside of a rust-colored meteorite from Mars. "But even if we're only finding Martian microbes, it raises exhilarating possibilities."
In many ways, Life on Mars - or "Des Traces de Vie Sur Mars," as the French newspaper "Le de Vie Sur Mars," as the French newspaper Le Figaro said Wednesday - is the headline mankind has been waiting for since the first human eyes looked into the heavens and saw God, fear or some amazing future journey.
"It might take a few days, a few weeks, even a few decades for this to sink into the popular culture," said Kim Stanley Robinson, 44, author of the best-selling "Red Mars" trilogy, which outlines the future human colonization of Mars.
"But when this sinks in, anyone who believes in the scientific method will see the thousands of stars in the night sky in a whole new way. They'll be looking at a universe just stuffed with life. If it happened two times in this one solar system, it means life is very common in the universe."
Authors, scientists, philosophers, fools and even some charlatans have been out on this same extraterrestrial limb before.
Galileo was convicted of heresy in 1633 for daring to suggest Mars and other planets were places like Earth. Lurid tales of Martians filled the 19th Century, long before H.G. Wells wrote "War of the Worlds" in 1897. And the latest discovery could mean a measure of vindication for American astronomer Percival Lowell, who started a new sensation in 1908 with his finding of "canals" criss-crossing the surface of Mars.
Neither life nor the canals were there when NASA's two Viking landers arrived in 1976. The talk now is that the landers weren't in the right place, or didn't dig enough to find the real Martian canals, microscopic and teeming with one-celled life.
In terms of great discoveries, a finding of life on Mars might end up being the main thing the 20th Century is remembered for, ranking with Columbus discovering a New World, the invention of the printing press or geometry. Or it might be just another scientific dead end, the bacteria on Mars turning out to be no more than some inorganic interplanetary yogurt.
"Until we find evidence of sentient life, most people will view this as `that's interesting,' " said David Pearce Snyder, an editor at Futurist Magazine. "If they had found a rusty knife blade then you would see a frenzied rush, a mobilization of world resources. But not with the possible fossil remains of one-celled animals. That's only a scientific curiosity."
At Harvard, paleontologist Stephen Jay Gould said scientists are almost ho-hum about the news. "E.T. is a 12. A bacterium is a 1.7," Gould said. "It's so unsurprising. It's not evoking in me and most paleontologists any wondrous new thoughts because we've been well aware of the likelihood that Mars was habitable for at least a billion years of its history."
Gould remains skeptical about the evidence as well. "We're talking about chemicals in cracks in rocks. There are a lot of ways it could get in,' including earthly contamination, he said.
Religion, too, seems ready to absorb this new bit of science. One-God, One-World might simply be narrow thinking.
"I don't see it as a big obstacle to religious thought. To be sure it's a further displacement of humanity from a unique status, but we've been facing that for a long time," said Ian Barbour, a physicist and theologian at Carleton College in Northfield, Minn. "The religious community has been slowly coming to grips with this over the years."
The Bible doesn't say there's no life on other worlds, although it does promise that life on Earth is unique. Islam's Koran refers to God as God of "the worlds." Some theologians say there's plenty of room for God's reach to grow.
"If this is true it can't contradict any true theory. It just may take some time to reconcile," said Patrick Ellis, president of Catholic University in Washington, D.C. "All the religions on Earth are based on human history. Other life forms may have an entirely different relationship to God. There's no limit to God's creative potential."
But for fundamentalist evangelist Jerry Falwell, "they can spend a trillion dollars looking for it (intelligent life) but they'll never find it. The Bible makes clear that Jesus Christ is the only mediator between God and Man" and that his work on Earth was entirely for the children of Adam and Eve.
How vast a family, the question then becomes, and the answers won't come anytime soon. Maybe all this is just another small step toward a giant meeting of minds. Maybe not. But after 3.6 billion years, there's no reason to believe we'll meet our interplanetary neighbors by the weekend.
For now, said historian Daniel Boorstin, former librarian of Congress, "the good effect of this discovery is to keep our imaginations open. The great obstacle to progress is not ignorance but the illusion of knowledge. Perhaps this little rock will destroy the illusion that we are alone in the universe."
Or even that we are homegrown. If a life-bearing meteor came to Earth 4 billion years ago, about the time similar processes were churning in the primeval soups here, could that mean we are only offspring of some off-world seed?
"Perhaps we are the Martians," said Seth Shostak, a radio-astronomer in Mountain View, Calif.
That's the idea that resonates deepest with Bradbury, who still dreams of Martian summers even as he asks for more proof. "We are here, dead matter left on Earth and struck by lightning and somehow life developed. We are something that is totally impossible," Bradbury said, the Los Angeles morning sun marking yet another turn of the Earth.
"It's time we land on Mars to find out for ourselves. Then there will be life on Mars and that life will be us."
Contributing: Lori Sharn, Andrea Stone and Adam Weintraub
-- Eric M. Choi | Author of "From a Stone", in the University of Toronto | September issue of SCIENCE FICTION AGE Institute for Aerospace Studies | magazine. Now available at bookstores email@example.com | and newsstands.
NASA Headquarters, Washington, DC
Johnson Space Center, Houston, TX
Stanford University, Palo Alto, CA
August 7, 1996
The NASA-funded team found the first organic molecules thought to be of Martian origin; several mineral 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.
"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 microsopic 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 igneous rock in the 4.2-pound, potato-sized meteorite has been age-dated to about 4.5 billion years, the period when the planet Mars formed. The rock is believed to have originated underneath the Martian surface and to have been extensively fractured by impacts as meteorites bombarded the planets in the early inner solar system. Between 3.6 billion and 4 billion years ago, a time when it is generally thought that the planet was warmer and wetter, water is believed to have penetrated fractures in the subsurface rock, possibly forming an underground water system.
Since the water was saturated with carbon dioxide from the Martian atmosphere, carbonate minerals were deposited in the fractures. The team's findings indicate living organisms also may have assisted in the formation of the carbonate, and some remains of the microscopic organisms may have become fossilized, in a fashion similar to the formation of fossils in limestone on Earth. Then, 16 million years ago, a huge comet or asteroid struck Mars, ejecting a piece of the rock from its subsurface location with enough force to escape the planet. For millions of years, the chunk of rock floated through space. It encountered Earth's atmosphere 13,000 years ago and fell in Antarctica as a meteorite.
It is in the tiny globs of carbonate that the researchers found a number of features that can be interpreted as suggesting past life. Stanford researchers found easily detectable amounts of organic molecules called polycyclic aromatic hydrocarbons (PAHs) concentrated in the vicinity of the carbonate. Researchers at JSC found mineral compounds commonly associated with microscopic organisms and the possible microscopic fossil structures.
The largest of the possible fossils are less than 1/100 the diameter of a human hair, and most are about 1/1000 the diameter of a human hair - small enough that it would take about a thousand laid end-to-end to span the dot at the end of this sentence. Some are egg-shaped while others are tubular. In appearance and size, the structures are strikingly similar to microscopic fossils of the tiniest bacteria found on Earth.
The meteorite, called ALH84001, was found in 1984 in Allan Hills ice field, Antarctica, by an annual expedition of the National Science Foundation's Antarctic Meteorite Program. It was preserved for study in JSC's Meteorite Processing Laboratory and its possible Martian origin was not recognized until 1993. It is one of only 12 meteorites identified so far that match the unique Martian chemistry measured by the Viking spacecraft that landed on Mars in 1976. ALH84001 is by far the oldest of the 12 Martian meteorites, more than three times as old as any other.
Many of the team's findings were made possible only because of very recent technological advances in high-resolution scanning electron microscopy and laser mass spectrometry. Only a few years ago, many of the features that they report were undetectable. Although past studies of this meteorite and others of Martian origin failed to detect evidence of past life, they were generally performed using lower levels of magnification, without the benefit of the technology used in this research. The recent discovery of extremely small bacteria on Earth, called nanobacteria, prompted the team to perform this work at a much finer scale than past efforts.
The nine authors of the Science report include McKay, Gibson and Thomas-Keprta of JSC; Christopher Romanek, formerly a National Research Council post-doctoral fellow at JSC who is now a staff scientist at the Savannah River Ecology Laboratory at the University of Georgia; Hojatollah Vali, a National Research Council post-doctoral fellow at JSC and a staff scientist at McGill University, Montreal, Quebec, Canada; and Zare, graduate students Simon J. Clemett and Claude R. Maechling and post-doctoral student Xavier Chillier of the Stanford University Department of Chemistry.
The team of researchers includes a wide variety of expertise, including microbiology, mineralogy, analytical techniques, geochemistry and organic chemistry, and the analysis crossed all of these disciplines. Further details on the findings presented in the Science article include:
American Association for the Advancement of Science News Release
Organic Compounds and Possible Biological Features
Found in Martian Meteorite,
Featured in 16 August 1996 Science
Washington, DC - Ever since scientists learned that water once flowed on Mars, they've wondered whether life might also have flourished on the apparently now-dead planet. In the 16 August issue of Science, McKay et al report the first identification of organic compounds in a Martian meteorite. The authors further suggest that these compounds, in conjunction with a number of other mineralogical features observed in the rock, may be evidence of ancient Martian microorganisms.
The paper's authors are David S. McKay and Everett K. Gibson, Jr., of NASA's Johnson Space Center in Houston, TX; Kathie L. Thomas-Keprta of Lockheed Martin in Houston, TX; Hojatollah Vali of McGill University in Montreal, Quebec; Christopher S. Romanek of the University of Georgia's Savannah River Ecology Laboratory in Aiken, SC; and Simon J. Clemett, Xavier D.F. Chllier, Claude R. Maechlin, and Richard N. Zare of Stanford University in Stanford, CA.
Organic (complex, carbon-based) molecules are the requisite building blocks of life on Earth. The authors looked for signs of such molecules and other mineralogical and textural indications of past life within the pore space and fractures of meteorite Allan Hills 84001 (ALH84001), one of only 12 meteorites identified as having come from Mars. ALH84001 is the oldest of the Martian dozen, having crystallized from molten rock about 4.5 billion years ago, early in the planet's evolution, and it is the only Martian meteorite to contain significant carbonate minerals. (The carbonates formed sometime after the rock, perhaps about 3.6 billion years ago.)
About 15 million years ago, a major asteroid impact on Mars threw ALH84001 into space, where it eventually fell onto an ice field in Antarctica about 13,000 years ago. ALH84001, which shows little evidence of terrestrial weathering, was discovered by meteorite-hunting scientists in 1984 and only recently identified at Martian.
ALH84001 is riven with tiny fractures resulting primarily from impacts that occurred while the rock was on Mars. The secondary carbonates formed along with some of these fractures. The *Science* authors prepared thin sample sections that included these pre-existing fractures, and found on their surfaces a clear and distinct distribution of polycyclic aromatic hydrocarbons (PAHs), organic molecules containing multiple connected rings of carbon atoms -- the first organic molecules ever seen in a Martian rock. A variety of contamination checks and control experiments indicated that the organic material was indigenous to the rock and was not the result of terrestrial contamination. For example, the authors noted that the concentration of PAHs increases inward, whereas terrestrial contamination likely would have resulted in more PAHs on the exterior of the rock.
The big question is: where did the PAHs come from?
It is thought that PAHs can form one of two ways: non-biologically, during early star formation; or biologically, through the activity of bacteria or other living organisms, or their degradation (fossilization). On Earth, PAHs are abundant as fossil molecules in ancient sedimentary rocks, coal and petroleum, the result of chemical changes that occurred to the remains of dead marine plankton and early plant life. They also occur during partial combustion, such as when a candle burns or food is grilled.
To address the origin of these PAHs, the authors examined the chemistry, mineralogy, and texture of carbonates associated with PAHs in the Martian meteorite. Under the transmission electron microscope, the carbonate globules were seen to contain fine-grained magnetite and iron-sulfide particles. From these and other analyses, the authors developed a list of observations about the carbonates and PAHs that, taken individually, could be explained by non-biological means. However, as they write in their *Science* article, "when considered collectively ... we conclude that [these phenomena] are evidence for primitive life on early Mars." Some of their observations are as follows:
* The higher concentrations of PAHs were found associated with the carbonates.
* The carbonates formed within the rock fissures, about 3.6 billion years ago, and are younger than the rock itself.
* The magnetite and iron-sulfide particles inside the carbonate globules are chemically, structurally and morphologically similar to magnetosome particles produced by bacteria on Earth.
* High-resolution scanning electron microscopy revealed on the surface of the carbonates small (100 nanometers) ovoids and elongated features. Similar textures have been found on the surface of calcite concretions grown from Pleistocene groundwater in southern Italy, which have been interpreted as representing nanobacteria.
* Some earlier reports had suggested that the temperature at which the ALH84001 carbonates formed was as high as 700' C -- much too hot for any kind of life. However, the isotopic composition of the carbonates, and the new data on the magnetite and iron-sulfide particles, imply a temperature range of 0' to 80'C, cool enough for life.
* The magnetite -- a mineral which contains some ferric (Fe3+) iron, perhaps indicating formation by oxidation (the addition of oxygen) -- and iron sulfide -- a mineral that can be formed by reduction (the loss of oxygen) -- were found in close proximity in the Martian meteorite. On Earth, closely associated mineralogical features involving both oxidation and reduction are characteristic of biological activity.
Science is the official journal of the American Association for the Advancement of Science (AAAS) in Washington, DC, the world's largest general science organization.
The following appeared in the March 25 issue of Science News:
"This meteorite is giving us a look at Mars early in its history, when it was a warmer, wetter planet," says Everett K. Gibson of NASA's Johnson Space Center (JSC) in Houston. He and his collaborators, along with several other research teams, reported their findings at the annual Lunar and Planetary Sceince Conference in Houston.
Originally misclassified as a fragement gouged from an asteroid (SN: 3/26/94, p. 206), ALH84001 has several intriguing properties, says Alan H. Treiman of the Lunar and Planetary Institute in Houston. For instance, among the 11 meteorites identified as chunks of Mars, ALH84001 has the highest concentration of carbonates.
The high carbonate content appears to support the long-held notion that water once flowed on Mars. Researchers speculate that carbonates crystallized within the meteorite when water rich in dissolved carbon dioxide percolated through rock just beneath the Martian surface.
In another finding, mass spectroscopy and electron microscopy reveal that ALH84001 contains polycyclic aromatic hydrocarbons (PAHs), report Kathie L. Thomas of Lockheed Martin Engineering and Sciences Co. in Houston and her colleagues. These organic molecules may originate from material delivered to Mars by comets that struck the planet.
Another interpretation is that the PAHs appeared as precusors of primitive life. On Earth, some PAHs are products of biological activity.
Measurements of the decay products of two radioactive elements confirm that ALH84001 is about 4.5 billion years old. Lawrence Nyquist of JSC and his colleagues announced at the conference. A team of German researchers reported a similar age last year.
Some scientists were reluctant to accept the earlier estimate, Myquist notes, in part because the other known Martian meteorites are much younger. With only about 4 percent of the present Martian surface believed to have survived unchanged from such an early era, some researchers doubted that Earth would get "free deliver" of so old a sample.
The great age of ALH84001 suggests that the Martian crust formed in a hurry, no more than 100 million years after the birth of the sun, Treiman says. But age is only half the mystery, he adds. In the standard model for crust formation, low-density material floats to the surface of a young, molten planet like scum on a pond. However, ASLH84001 contains relatively high-density material, including the mineral orthopyroxene. How could such a rock become part of the Martian crust?
"We're all puzzled," Treiman says.
NASA Headquarters, Washington, DC
August 6, 1996
The evidence is exciting, even compelling, but not conclusive. It is a discovery that demands further scientific investigation. NASA is ready to assist the process of rigorous scientific investigation and lively scientific debate that will follow this discovery.
I want everyone to understand that we are not talking about 'little green men.' These are extremely small, single-cell structures that somewhat resemble bacteria on Earth. There is no evidence or suggestion that any higher life form ever existed on Mars.
The NASA scientists and researchers who made this discovery will be available at a news conference tomorrow to discuss their findings. They will outline the step-by-step "detective story" that explains how the meteorite arrived here from Mars, and how they set about looking for evidence of long-ago life in this ancient rock. They will also release some fascinating images documenting their research.