Question submitted to the MESSENGER website at Johns Hopkins Applied Physics Lab

Dear Sir. I work in the aerospace field, and I have a physics PhD. There is nothing about my question in your archives. I am wondering if anyone has done a rough calculation of the underground temperature of Mercury vs. depth and latitude? I understand that the equatorial surface temperature changes between 90K and 700K as the planet rotates. But below 1-2 meters, the temperature would be relatively constant somewhere between these two extremes, and it would vary with depth and latitude. I am wondering if there is some depth and latitude where the temperature is a balmy 296K (room temperature)? If so, an underground base could be put there, and the underground location would also provide shielding from ionizing radiation, and it would make the lack of atmosphere less important. In addition, the strong solar radiation on the surface would provide unlimited power via solar arrays. And with unlimited power one can make almost anything needed for survival. Finally, if there is some depth and latitude where the temperature allows a Mercury base, why not a whole Mercury colony in an underground ring circling the planet?

- submitted by Dr. James Shifflett , 06-22-2011

Modeling of Mercury's subsurface temperatures has been carried out for several purposes, including finding the depth at which rocks are below the Curie temperature and hence could retain a magnetic signature, relating temperatures to the mechanical behavior of rocks to help understand tectonic features, and to determine the stability of polar volatile species. Modeling by David Paige of the University of California at Los Angeles indicates that at 84 degrees North, 90 degrees East (i.e., a longitude opposite Mercury's "hot poles"), the mean annual temperature at a depth of 1 meter below the surface is about 120 kelvin, suitable for retaining water ice. Moving toward the equator, the depth to a given temperature will increase. So certainly there are many locations where an insulating layer of regolith could provide for stable, temperate conditions. Getting humans to Mercury and constructing extensive subterranean habitats would be a challenging and expensive undertaking, however.

--Dave Blewett, Johns Hopkins University Applied Physics Laboratory, MESSENGER Participating Scientist