[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]

So how long do we wait? Say MSL or some other rover in the next 20 years finds...

I do not know. As a child of the space age growing up in the 1960's I have long dreamed of zipping up a spacesuit and clomping around on Mars. But now that we are wiping our feet on Mars' doormat I have reservations about leaving our molecular footprints until we find out what is there.

--Bill

[paxdan]

So how long do we wait? Say MSL or some other rover in the next 20 years finds...

I do not know. As a child of the space age growing up in the 1960's I have long dreamed of zipping up a spacesuit and clomping around on Mars. But now that we are wiping our feet on Mars' doormat I have reservations about leaving our molecular footprints until we find out what is there.

--Bill

Earth and Mars have been swapping material since the formation of the solar system. We've found mars rocks here, even a bit of phobosite. And while earths gravity well is deeper than that of mars, I don't doubt that with the rich biosphere which has existed here and the near ubiquity of microorganisms in the first couple of Km's of the earths crust that at least a few bacteria have made the ride. I am certain also that we have sent life. I worked for a year as an undergrad in a Category 3 containment lab working with nasty pathogens, and while this doesn't make me an expert on biocontamination. If there's one thing I know it is that bacteria are tough little buggers and they get everywhere. I am confident that we have sent life (or its remnants) to mars on every craft dispatched so far.

In short I think the debate as to whether we should risk contaminating is moot. In fact I think the use of the word contaminate is wrong as it implies that some form of containment is being breached. Well those millions of kilometres of vacuum have been breached thousands (if not millions, or billions) of times during the last 4.5Gyr and we've done a good job in the last 45. It just isn't a pristine planet.

When we go to mars, of course we should do everything possible to minimise the exposure to our biota, but not at the expense of our next small step.