Eby says: Does a good job exposing why the naked spore ideas/bioparticle of BD's benefactor (cardiff astrobiology research associate?) and ICAMSR BOD buddy Charndra W. are unlikely while transport inside Martian meteorites is much more likely. Funny how BD embraces the former but rejects the latter.

Regards,
Mark

Mark,

I am well aware of Dr. Horneck, Mancinelli and the others who work on this subject. Conversly, Dr. Benton Clark has published on this very subject (cut and paste) and feels the likely hood of life surviving long enough in solid rock in space to reach Earth in a viable state is questionable. Why can you not accept his work on this subject?

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2001OLEB...31..185C&db_key=AST&high=3de6125d8d25322

Planetary Interchange of Bioactive Material: Probability Factors and Implications - Clark, Benton C.

Abstract

It is now well-accepted that both lunar and martian materials are represented in the meteorite collections. Early suggestions that viable organisms might survive natural transport between planets have not yet been thoroughly examined. The concept of Planetary Interchange of Bioactive Material (PIBM) is potentially relevant to the conditions under which life originated. PIBM has been also invoked to infer that the potential danger to Earth from martian materials is non-existent, an inference with, however, many pitfalls. Numerous impediments to efficient transfer of viable organisms exist. In this work, the lethality of space radiation during long transients and the biasing of launched objects toward materials unlikely to host abundant organisms are examined and shown to reduce the likelihood of successful transfer by orders of magnitude. It is also shown that martian meteorites studied to date assuredly have been subjected to sterilizing levels of ionizing radiation in space. PIBM considerations apply to both the solar system locale(s) of the origin of life and to the applicability of planetary protection protocols to preserve the biospheres of planetary bodies, including our own.

The space.com article only addresses life transferred in solid rock. What about a rock/ice mixture as found in comets? Organisms preserved this way might last hundreds of millions of years. The article really does not address that issue and that is what Wickramasignhe is talking about. The fact that life can survive as dormant spores in solid rock for a few hundred thousand years should tell us that perhaps life could survive indefinitely inside a water/ice comet. Instead of bicker about it, maybe we should wait until more data is obtained.

No hard samples of cometary material have been obtained and returned to Earth yet. Prelimanary studies do show that comets show indications of large organic molecules. Hmmm...wonder what they might be! And as for my view on Martian meteorites carrying life to Earth (for the millionth time) -- I don't reject that life from Mars came to Earth in a meteorite from Mars at some point in history, although we have no solid evidence to show it has. Dr. Benton Clark says that lypholized life inside rock probably would not survive as viable spores after 100,000 years in space. Take for example ALH84001 (the only meteorite from Mars found to contain hints of fossilized life) - this meteorite spent millions of years in space before impacting Earth. Therefore there would be no viable spores inside.

Perhaps a meteorite of under 100,000 years of age did strike Earth, however, we just don't know what effects it may have had on terrestrial life do we? Many mass extinctions have occured throughout history, including the mysterious mass extinction of the Pleistocene mammals only 10,0000 years ago. Until we have more detailed information about Martian organisms (if any exist) any samples must be treated as biohazardous. So far, no one has figured out a good way to return samples safely (as indicated in the SSB publications I listed for you during the last few days. NASA's Planetary Protection Officer John Rummel made this point at a recent AGU Conference. Here is the abstract for you (cut and paste):

http://adsabs.harvard.edu/cgi-bin/nph-bib_query?bibcode=2002AGUSM.P51A..09R&db_key=AST&high=3de6125d8d15768

Mars Sample Handling for Planetary Protection -
Rummel, J. D.

A sample return mission from Mars is being planned in the context of an emerging wave of new data about Mars. These data are consistent with the hypothesis that life could occur somewhere within the geosphere of that planet, as well as with the hypothesis that some Earth organisms alive today could find habitable niches in the martian subsurface, at least. As such, NASA's Mars Exploration Program is being planned to avoid the biological contamination of Mars, and with an understanding that NASA will follow the US National Research Council's recommendations that samples returned from Mars should be contained until "rigorous analyses determine that the materials do not contain a biological hazard." With this planning in mind, NASA, with the help of other US and international participants, has been working to develop a protocol for sample analysis: a list of comprehensive tests, and their sequential order, that will be performed to fulfill the NRC recommendation. It is the intent of the protocol that it will achieve the testing required to meet the criteria to release samples for analysis outside of an initial containment facility. Because the amount of sample to be returned is thought to be small (500-1000 grams) this protocol hopes to maximize the utility of the tests that will be used in assessing the potential hazard. These tests include physical and chemical characterization of the sample to support biohazard testing, the biohazard testing itself (which may involve molecular- and organism-based testing), and focused life-detection analyses at the molecular level. The protocol is being developed as a living draft, with the expectation that a final protocol will only be shaped at the time of the actual development and testing of a Mars sample receiving facility and the sample-return mission itself.

Also, Dr. Chris Chyba points out two examples of why we should be extremely cautious about MSR (cut and paste):

Planetary Protection: Two Relevant Terrestrial Examples
Authors: Chyba, C.

Abstract

Concerns about potential pathogens in returned samples from Mars ("Mars Sample Return: Issues and Recommendations", National Research Council, 1997) or planetary satellites ("Evaluating the Biological Potential in Samples Returned from Planetary Satellites and Small Solar System Bodies", National Research Council, 1998) focus on two potential types of pathogenesis, toxic and infectious. The National Research Council reports cited above state that the chances of extraterrestrial organisms proving either toxic or infectious to humans are extremely low, but cannot be entirely ruled out. Here I discuss recently discovered terrestrial examples relevant to each possibility, in order to make these concerns concrete. The first example concerns the production of hepatotoxins (toxins affecting the liver) and neurotoxins by cyanobacteria in glacial lakes on alpine pastures in Switzerland. In this example, mat-forming benthic cyanobacteria are implicated in a hundred cattle poisonings that have been reported from alpine pasteurs in southeastern Switzerland over the past twenty-five years (e.g. K. Mez et al, Hydrobiologia 368, 1-15 (1998)). It is unlikely that these cyanobacteria evolved the toxins in response to dairy cows; rather the susceptibility of cattle to these toxins seems simply to be an unfortunate coincidence of a toxin working across a large evolutionary distance. The second example concerns the recent demonstration that the decimation of shallow-water Caribbean elkhorn coral is due to infection by a common fecal enterobacterium associated with the human gut (K. L. Patterson et al., PNAS 99, 8725-8730 (2002)). The bacterium, Serratia marcenscens, is also a free-living microbe in water and soil, as well as an opportunistic pathogen in a variety of animal species. The distance between humans and corals emphasizes the possibility that certain organisms may prove pathogenic across a wide evolutionary divide. Of course, in neither of these cases are the evolutionary distances crossed as large as those that would likely exist between any martian organisms and human beings. The possibility that life on the two worlds might share a common ancestor suggests that these distances may not be altogether incomparable, but this remains speculation pending further exploration.