Letters
Life on Mars from Earth?
In NASA’s careful attempt to avoid contamination of Martian rocks by Earth’s sources of life, nothing was mentioned about the possibility of organic artifacts from Earth being found on Mars ("Scooping Up a Chunk of Mars," SN: 4/25/98, p. 265). If Mars rocks can land on Earth, is it not likely that, in the past, Earth material made it to Mars?
Thus, even if some "evidence" of life is found in the retrieved samples, how can we be sure that it did not originate on our own planet in a previous era?
Del Dietrich
Campbell, Calif.Testing the biological quarantine process for the Mars robot on an actual mission to Mars sounds expensive and time-consuming. Why not test the process with a trip to the Moon?
It would be quicker and probably less expensive. Moreover, previous visits to the moon would provide adequate controls for comparison of possible contaminants, and any snafus in handling the landing craft would be exposed.
Tim Davis
Broomfield, Colo.Long before the probe’s expected return in 2008, NASA’s International Space Station should be in operation. What better laboratory for investigating potentially dangerous samples while remaining completely isolated from the atmosphere?
Ian Randal Strock
Brooklyn, N.Y.It seems odd to me that no discussion is presented regarding the worst-case scenario represented by the Andromeda Strain example given at the beginning of the article. In the climax of that fictitious classic, the strain gets loose despite all precautions.
This brings me to my point.
Why parachute the samples down to Earth at all? Why not conduct the testing for toxicity in an orbital facility that can be directed into the sun should the worst occur?
Bill Chandler
Shawnee, KansasJohn Rummel, NASA’s Planetary Protection Officer, replies:
"We tested some of the quarantine procedures as part of the Apollo missions to the moon. Many of the lessons we learned from Apollo are pertinent to Mars, and what was not learned there can be suitably tested using Earth-based methods (airdrops of containers, laboratory studies, and so on), so a new lunar mission is unnecessary.
"There are two problems with using the Space Station as a laboratory. First, one of the reasons for having the Space Station is to understand the adaptation of life to microgravity and to use microgravity as a probe to study organisms in a novel way. The requisite controlled studies for a sample’s biological effects cannot be done on the Space Station until we have extensive knowledge of microgravity physiology—a process that could take decades (to be optimistic).
"Second, the Space Station is preferable to Earth’s surface only if you believe that containment might be breached and, if so, you would be prepared to sacrifice the crew in the event of an ‘unknown or adverse reaction’ to the sample. Similar concerns obtain in a Space Shuttle recovery of samples while in orbit. Moreover, a Shuttle recovery might be less safe, overall, than direct entry.
"As to our ability to sterilize a sample, there is no doubt that high temperatures will be able to break carbon bonds and eliminate a threat posed by carbon-based life. The trick is learning how to sterilize such a sample without destroying the scientific information that led you to collect it in the first place. Between containment, corrosives, and heat, there should be ample margin for a safe analysis of materials returned from Mars." —R. Cowen
CORRECTION
In "Blood test, 3-D graphics win top prize" (SN: 5/23/98, p. 327), a photo of Jonathan Kelner was incorrectly identified as a photo of Geoffrey Schmidt.
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Table of Contents -- June 13, 1998