According to a new study published in the journal Science Advances, the Martian subsurface would have been the most habitable region for simple life forms on the planet, likely due to underground melting of thick ice sheets fueled by geothermal heat. Ojha et al. demonstrate that the geothermal heat would have played a key role in early Martian habitability and hydrology during the Noachian period. Image credit: M. Kornmesser / ESO / N. Risinger, skysurvey.org. The...