Martian Cave Probe?, Designs for the DEEP Search for Life Options

[Shaka]

Does anyone consider it worthwhile to speculate on how we might explore Martian caves or lava tubes for the traces of life - past or present? I have not yet run across any 'official' proposals for "spelunker probes", so perhaps we could have some fun and get in on the ground floor with some feasible early designs. With the engineering and scientific expertise we have at UMSF we should be able to whittle down the possible features for such a rover to a practical core. If the planned surface scrapers and drillers don't turn up conclusive evidence to answer The Big Question, can we justify a search of the Martian Underground?

I can envisage a RTG-powered rover that enters a cave, or rappels down a skylight opening, leaving a base communication stage outside connected to it with a fiber-optic umbilical cable. Some form of laser or other illumination - in the visible and/or infrared - would presumably be required. How many of the MSL instruments could be included? What novel instruments would be appropriate? What is the optimal size and mobility design? 'Do we yet have 'hot' prospects for accessible caves? How should we choose the best candidates?

We can leave this to some JPL bright spark to develop, or we can dive right in. Any takers?

[Shaka]

You get my drift, nprev. Elevation could be a crucial criterion (krikeys! A Crushingly crucial criterion!), but so could be the proximity of geothermal warmth. There must be at least a few caves down amongst all those canyons and rills and badlands and chaotic terrains that could represent a final refugium for the never-say-die remnants of a past Martian biosphere. A refuge from the withering surface assaults of impact barrage, radiation, desiccation, freezedrying, peroxidation etc ad nauseam. Indeed, if there has been the vast underground labyrinth of water/ice systems, subject to sudden outfloods, drainage, rising and falling water tables etc, there MUST be a Martian underground. The remnants of Martian life may have abandoned the hostile surface so long ago that they don't even remember that the surface exists. Drilling down a meter or two may be no more productive than drilling into a Sahara dune. We may have to ferret out the ventilation shafts, the skylights, that offer access to the 'command bunker' of Martian life. (Disable poetic license)

I think it's fair to assume, for the mental exercise, that openings to the underworld have been or will be found. We won't be waiting for the first astronauts to set foot on Mars, and tell them "Just climb down there and see what you find." Even if we wait for man to reach Mars, we will first explore those hazardous nether-regions only with robot probes. So why wait for man? Let's at least put on paper, or the web, a scheme for exploring a cave. (If it's fruitless, Doug can always delete it.)

Happy Thanksgiving Day Parade to all!

[dburt]

...the proximity of geothermal warmth. There must be at least a few caves down amongst all those canyons and rills and badlands and chaotic terrains that could represent a final refugium for the never-say-die remnants of a past Martian biosphere. A refuge from the withering surface assaults of impact barrage, radiation, desiccation, freezedrying, peroxidation etc ad nauseam. Indeed, if there has been the vast underground labyrinth of water/ice systems, subject to sudden outfloods, drainage, rising and falling water tables etc, there MUST be a Martian underground. The remnants of Martian life may have abandoned the hostile surface so long ago that they don't even remember that the surface exists. ...

With regard to moisture and geothermal warmth, why restrict yourself to a cave? The climate inside a cave, unless it is a very deep one indeed, represents the average of the climate at the surface (averaged over day/night and winter/summer) so that any Mars cave is likely to be extremely cold inside, and not necessarily a promising place for life. For me the best refuge for life might be near the vent of one of those very long-lived but largely quiescent Tharsis volcanoes - potentially lots of warmth, moisture, and energy-yielding chemistry, persisting for billions of years at the same spot (no plate tectonics to move it around). Aperiodic eruptions of basalt need not wipe out life for more than a meter or two away from the vent contact, and it could easily re-establish itself afterwards.

Given that drilling to any significant depth is likely to be prohibitively expensive and fraught with mechanical difficulties, why not plan to land our magic rocket in the summit caldera of a volcano (perhaps not one of the tallest ones) and lower our cable of instruments down an old vent or old fumarole, if one could be located? Alternatively, look among the local throat-clearing volcanic ejecta or caldera collapse breccias around the rim for signs of past life. On Earth the closest analog for such a target might be the active biological communities first discovered during the late 1960's near "black smokers" or submarine volcanic vents (above sea floor spreading centers between separating tectonic plates or in regions of extension behind island arcs). Just another idea (one that I've mentioned previously, I believe). What do you think?

-- HDP Don