The Spelunking Spider

The timely announcement of local methane concentrations could enhance the chances that the MSL rover might be sent to one of these sites to investigate. If the MSL can sort out the isotopic ratios of the carbon in the methane, biomarkers associated with C12 can be observed.

If the isotopic analysis should support a biogenic signature, it will be difficult for the MSL to dig even a few meters much less kilometers to observe prospective biota.

Now it may be that the gas is exiting from what appears to be a point source similar to what is seen at the starting points of Dark Slope Streaks that could be consistent with the artistic images shown at the press meeting where the gas travels up to an impervious layer and then moves sideways until it exits out a face or point.

But it would be quite exciting if the gas were exiting from a cave. However, MSL does not have nightlights built upon the rover nor enough of an independent energy source to keep the lights on, nor the dexterity to navigate climbing down a cave. Much like the other two rovers on Mars, it will take advantage of sunlight to regenerate power. Also it is easier to transmit a signal from the surface than from underground.

If the MSL encountered a cave that was the source of one of the plumes, it would be nice if it had a detachable “spider” robot that had its own power and nightlights and the ability to transmit to the rover waiting outside the cave. Rather than trying to dig kilometers deep, the idea is to simply take advantage of the pre-existing “mine shaft” or cave to trace down to where the gas appears to source.

Do I think this is a likely scenario? The short answer is no, for then there is no obvious reason why the gas release is seasonal where the likely reason is that seasonal water or CO2 ice can plug small vents and then melt or sublimate away in the spring to allow the gas to escape. A cave entrance would normally be too large for an ice plug. But a landslide might have superficially closed the mouth of a cave to where ice plugs could be effective. One may only have to dig a short distance to get into a much larger cave. There might be surface clues that could point to cave openings that a trained eye might point to as a cave suspect.

So it might be important to task the MRO to take HiRes of suspected methane source areas images to look either directly for cave openings or for the slight telltale indicators that night point to a cave that has been obscured by a landslide. Without a cave there is no need for a “spelunking spider” and it is not part of the present MSL design anyways, but if we can decipher from MRO images that the suspected methane release zones do have what appears to be caves, we might have wished, alas too late, that we had these spiders along with the MSL to possibly see the underground source.

A problem with the MRO images is that they have a lot of information in them and there are not enough human eyes here on Earth to look at the images to find the information we are seeking. There have been campaigns to find the Beagle or the Mars Polar Lander from MRO images, but no success yet even though we believe they are down there somewhere. By contrast, here we are not sure if any caves actually exist in the areas of interest.

If caves should be spotted in MRO images that correlate with potential emission sites, it might actually be more appropriate to wait until a more specialized mission can be designed and sent to this site of interest. All the MSL targets have value and it is unfortunate we can not MIRV all of them at once with one payload carrying multiple MSL rovers. If they send the MSL to the methane site and it discovers that biomarkers are present and enhanced at the mouth of a cave, the NASA team may be quite besides themselves with curiosity and want to send the MSL in to investigate which most likely will result in a sudden end of mission and questions unanswered. This would be because the mission is unprepared for the discovery of a potential cave without any means of exploring it for suspected biota.