[X] My Assistant

[dilo]

This mosaic of 4 Panoramic frames from Sol442 show a strong increase in density of rocks, even big ones! Don't know if could be an issue for further movements toward the hill top?

[Bill Harris]

Good post(s), Bruce. The critical problem we face is ensuring that we do not contaminate Mars with our DNA or microbes. It would be terrible to not be able to determine if that bug or DNA fragment was ours or theirs.

Admittedly, Mars may be contaminated by earlier spacecraft or "earth meteors", but we can't risk more episodes.

Sending an orbiting laboratoryt Mars will be a tremendous undertaking, but the overhead of safely and sterile-ly landing a human on Mars is more tremendous. It's that last step down to qnd out of Mars' gravity well that is the dilly. For the cost (in terms of both $ and mass) of "one flag-waving clown on Mars" a dozen or more Rovers could land and work for many Sols.

--Bill

[dvandorn]

Admittedly, Mars may be contaminated by earlier spacecraft or "earth meteors", but we can't risk more episodes.

Very good point, Bill. Especially about earlier spacecraft. NASA had all of the American craft designed to land on Mars sterilized, I know (the Vikings, Pathfinder and the MERs, as well as MPL), but what about MCO? And IIRC, the Russians did *not* go through a sterilization process on their Mars landers -- several of which sem to have reached the surface, if not in operational condition.

It's very true that a trace of biomatter on a crashed Mars probe is far less likely to contaminate the whole planet than a whole human outpost -- people exist in a veritable soup of microbes, parasites and symbionts. Our very breath contains organic material. Filters designed to keep such particles from moving one way or another are expensive and clog up easily -- they could be an answer for very short-term human stays on the surface, but would become a maintenance nightmare on a months-long stay.

By the same token, it's fair to say that human-delivered micro-organisms would get sterilized pretty quickly by the Martian surface conditions, as would any Martian microbes -- we're going to have to look beneath the surface to find any evidence of the latter, I'm sure.

It all comes down to intentions, I think. If we never intend to try and establish a human presence on Mars, then it makes sense to *never* even attempt to land there -- it would pose far too great a risk of contamination. However, if we *do* intend to put humans on Mars to stay, then by definition we will be *intending* to place a terrestrial environment on Mars (no matter what extent). In which case, the problem becomes maintaining "pockets" of uncontaminated Martian environments for study.

Since we're operating with a severe lack of information on the quantity, distribution and current status of Martian biotics, *any* discussion of cross-contamination -- either way -- is an exercise in energetic arm-waving. And since we're a long way from making firm plans about landing humans on Mars, we have many, many opportunities to expand our data on Martian biotics before we commit men and materiel to *any* such plan. Hopefully, by the time we *do* start serious work towards a manned Mars landing, we'll have more information and can make rational decisions about the contamination risks.

-the other Doug