Life on Mars?

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Life on Mars?

Was There Once Life on Mars?
The Story

"Today, rock 84001 speaks to us across all those billions of years and millions of miles. It speaks of the possibility of life." -- President Bill Clinton.

NASA and Stanford University scientists announced Wednesday, August 8, they had compelling, but not conclusive, evidence that primitive microscopic life may have existed several billion years ago on the planet Mars.
[image of microfossil]       At a press conference in Washington Wednesday afternoon, a team of scientists led by Dr. David McKay of NASA's Johnson Space Center presented several key pieces of evidence which, put together, "strongly suggests" that life once existed on the Red Planet.
       "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.

The Evidence
The team presented four lines of evidence obtained from the analysis of a meteorite ejected from Mars billions of years ago and landed on the Antarctic continent over 10,000 years ago.
[image of meteorite]       The first was the confirmation that the meteorite came from Mars, based on compositional analysis of the rock, and the discovery of globules of calcium carbonate. These globules formed in cracks in the rock as the carbonates settled out of solution on the early Mars.
       The second line of evidence was the correlation of these globules with biological activity. Such globules are formed on Earth by microorganisms, and the size of the globules (250 millionths of a meter, or five times the thickness of a human hair) is consistent with terrestrial globules created by living creatures.
       A third line of evidence came from the microscopic examination of the globules. Scientists noticed the globules have alternating white-and-black rims ("Oreo cookie rims," as one scientist called them) composed of the minerals magnetite, phyrrhotite and greigite.
       Using a transmission electron microscope (TEM), scientist Kathie Thomas-Keprta was able to study the distinctive shapes and chemical composition of crystals of these minerals as well as the environment in which they formed. The characteristics of the crystals closely match those found on Earth created by microorganisms.
       "They may be created by complicated inorganic explanations, but the simplest explanation is an organic origin," Thomas-Keprta said.
[image of eggshaped globule]       The final, and most controversial, line of evidence was scanning electron microscope images of the surfaces of the globules. The surfaces showed a large number of elongated forms which can be explained by microfossils formed by bacteria or other microorganisms.
       The surfaces can also be explained by weathering and other inorganic processes, but McKay said they favor an organic origin for the structures seen.

"Skeptical Optimism"
Not everyone was optimistic or enthusiastic as the NASA scientists. Dr. William Schopf of UCLA, a scientist not part of the discovery, expressed a "note of caution" about the findings.
       Quoting famed astronomer Carl Sagan, Schopf said, "Extraordinary claims require extraordinary evidence." He applied seven critical tests of his own on the data, based on the both the meteorite and the organic samples found within.
       While acknowledging that the age and origin of the rock, as well as the existence of indigenous organic material, was well known, he was less supportive of the claims of microfossils and biologic origins for the organic materials.
       He noted that the fractures in the meteorite, in which the globules of organic materials were found, may have been formed when the meteorite was ejected from mars by an asteroid impact. If that was the case, and if the meteorite was subject to high temperatures during that time, it is unlikely that any organic material found in the meteorite could have been created biologically on Mars.
[image of globule]       He was also less than convinced that the organic materials found in the meteorite came from living creatures, stating that organic materials have been found on other meteorites with no biological formation claimed.
       The microfossils claimed by the researchers are also 100 times smaller than similar microfossils found in terrestrial rocks, according to Schopf.
       Two Viking landers carried experiments designed to look for microscopic life forms in the Martian soil. After puzzling early results, scientists concluded no such life forms currently exist on Mars, at least near the surface.
       He concluded that more science was needed to move a biological explanation for the data "up the probability scale."

Reaction from Goldin, Clinton
Schopf's conclusion was readily agreed by NASA Administrator Dan Goldin. "This is the most important thing that must be done," he said.
       Goldin also appealed for a logical, scientific approach to future work, rather than making any appeals to emotion. "We will be governed by scientific thought and principles and not emotion," Goldin said.
       President Clinton also expressed his support for further research on the possibility of ancient Martian life. Speaking shortly before traveling to California on a campaign trip, he said, "Like all discoveries, this one will and should continue to be reviewed, examined and scrutinized. It must be confirmed by other scientists."
       "The fact that something of this magnitude is being explored is another vindication of America's space program and our continuing support for it, even in these tough financial times," Clinton said. "I am determined that the American space program will put its full intellectual power and technological prowess behind the search for further evidence of life on Mars."
       Clinton used the opportunity to announce the creation of a bi-partisan "space summit" led by Vice President Al Gore, which will meet later this year. "A significant purpose of this summit will be to discuss how America should pursue answers to the scientific questions raised by this finding," Clinton said. [Ed. note: As of early February 1997 the summit had not taken place or even been scheduled.]

Although the results announced today were not conclusive, scientists were clearly very optimistic about the implications of the data.
       "If it [life] originated in this solar system, and on more than one planet in the solar system," said NASA official Wesley Huntress, "why wouldn't it originate in other solar systems?"
       Acknowledging the highly unlikely but not impossible hypothesis of cross-pollenation of primitive lifeforms between the two young worlds, Stanford chemist Dr. Richard Zare said, "Who is to say we are not all Martians?"

Related News Stories -- 1996 August 8
Clinton Announces Space Summit
Goldin Chooses Logic Over Emotion
Space Advocacy Groups Divided Over Future Plans
How Do We Know It Came From Mars?
Future Missions to Mars NRC Criticizes Future Mars missions

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