I was thinking the same thing, myself.

But there could exist subterranean life on Mars. Although Mars is geologically dead, Mars’ core is molten, fueled by fission, which is what drives geologic activity here on Earth. On Earth, temperatures rise dramatically just beneath Earth’s crust; things begin to warm up even at depths as shallow as a kilometer, or less.

Under a couple of miles of frozen carbon dioxide and ice, huge lakes of subterranean water could exist all over the Mars similar to Antarctica’s Lake Vostok. I can imagine vast subterranean Martian lakes being blanketed at their surfaces by dense concentrations of carbon dioxide gas. Such an environment could support diverse forms of life.

If Mars ever harbored life, then life surely persists there now.

While the discovery of life on Mars would result in a paradigm shift here on Earth and would lead to a better understanding of Earth’s subterranean sphere of life (as well as of Earth’s biosphere), on Mars, itself, life would be for us, and would remain for us, nothing but a fascinating and valuable object of study.

If life ever existed on Mars, gravity ‘lite’ combined with the Sun’s intense radiation spells subterranean life (most likely microbial).

P.S.: One thing I liked about this documentary was the virtual absence of background ‘music’(noise).