[CNI News thanks Errol Bruce-Knapp, Patricia Welch and Skye Turell for assistance with this story.]
A panel of the National Research Council said on Thursday, March 6, 1997 that steps must be taken to prevent possible contamination of the earth by Martian microbes that might be brought back in robotic "sample return" missions, as well as later manned missions to the Red Planet.
In related news, a report in the March 14 edition of the journal Science presents new research supporting the hypothesis that ancient bacterial life is contained in a meteorite from Mars. And a panel of science experts will present new data and deliver a progress report on the continuing "Past Life on Mars" discussion at a press briefing scheduled for Wednesday, March 19 in Houston, Texas.
"If life forms ever existed on Mars, either by having been formed in an independent origin or having been transferred there from Earth, it is possible that they have continued to exist up to the present time," says the National Research Council report, titled, "Mars Sample Return: Issues and Recommendations."
While "it is doubtful that (the microbes) could adapt to Earth's environment or cause significant harm, the risk is not zero," the council warned.
The report recommends that rock samples "should be isolated physically and biologically and regarded as hazardous until proved otherwise." As part of a "planetary protection policy," the council urged NASA to be prepared, if necessary, to:
-- sterilize a returning robot probe, perhaps in space, before it returns to Earth, or
-- leave the probe in space where alien microbes wouldn't hurt anyone.
The council is the research arm of the National Academy of Sciences, the nation's most distinguished scientific organization. It advises the federal government on scientific issues, and its counsel often sways national policy on technical topics.
Following the announcement last August of possible evidence of fossil bacteria in a Martian meteorite, NASA has greatly stepped up its plans to explore Mars. Two NASA spacecraft, Mars Pathfinder and Mars Global Surveyor, are en route to Mars now, due to arrive in July and September, 1997, respectively, though neither is designed to return to earth. Robotic "sample return" missions are much more difficult and costly than the current missions, but plans are underway to attempt such a mission early in the next century.
Despite the possibility that Martian samples might contain alien germs, the research council report states that the danger is minimal because such organisms would probably have a hard time competing in the earth's robust ecosystem. Besides that, the council says, the vast majority of microbes known on earth are harmless to other forms of life.
Nonetheless, in the face of the momentous unknowns of extraterrestrial life, all precautions must be taken, the council says.
Meanwhile, new isotopic analyses of the meteorite that provided hints of past life on Mars reveal a low-temperature origin, boosting the idea that features of the meteorite may have been formed by living organisms.
The study, published March 14 in the journal Science by a team led by University of Wisconsin-Madison geochemist John W. Valley, lends powerful new support to the notion that the carbonate globules found within meteorite ALH84001 were formed on the Red Planet under conditions consistent with life.
The isotopic procedures employed by Valley and his colleagues were developed specifically for the Mars rock. Results contradict claims that the carbonate globules found in the rock were formed at blistering temperatures too hot to support life, or were formed on Earth, two primary arguments advanced against the meteorite as evidence of past life on Mars. "Everything we see is consistent with biological activity, but I still wouldn't rule out low-temperature inorganic processes as an alternative explanation" said Valley. "We have not proven that this represents life on Mars, but we have disproven the high-temperature hypothesis."
The new study was conducted by a team that includes Valley, John M. Eiler and Edward M. Stolper of the California Institute of Technology, Colin M. Graham of the University of Edinburgh, Everett K. Gibson of NASA's Johnson Space Center, and Christopher S. Romanek of the University of Georgia.
The upshot of the analysis is that the carbonates most likely precipitated at temperatures below 200 degrees Fahrenheit, under conditions hospitable to some forms of microscopic life.
As interest in the possibility of Mars life continues to grow worldwide, a panel of science experts will present new data and deliver a progress report on the continuing "Past Life on Mars" discussion at a press briefing scheduled for 1 p.m. EST on Wednesday, March 19.
Douglas P. Blanchard, Ph.D., Chief of the Johnson Space Center's Earth Science and Solar System Exploration Division in Houston, Texas, will moderate a panel of six authors whose papers on the Mars issue are scheduled for presentation during a special plenary session of the Lunar and Planetary Science Conference taking place March 17-21 in Houston.
The briefing will be carried live on NASA Television. The text of complete abstracts to be presented may be obtained in advance of the event at web site for the 28th Lunar and Planetary Science Conference at: http://cass.jsc.nasa.gov/LPSC97
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