Hello Barry -

This is CO2. You have CO2 clearly subducted near the surface of Mars (proven).

Given the different effects of asteroid and comet impact on the CO2 and H2O trapped in Mars lithosphere, visible in the images of Mars´ craters, you have clathrates.

That said, you also have high energy neutrons showing water - total amounts not yet clear, but minimal. Water trapped immediately beneath the surface of any fracgtured translucent crystal will likely become liquid occasionally, and most likely some form of life will be found there.

Thus the unknown degree of hazard possible from Mars biosphere is not appreciably reduced, and while the focus of locations for the search for life changes, the need for extreme caution is not reduced.

ep