Implications for extraterrestrial research
Finding DNA looks most promising
If Hydrogen is present, the remainder of hydrogen oxydizing life using e.g. Fe(III) as electron acceptor could be present.
Is extraterrestrial life completely autotrophic or mixed auto-/heterotrophic?
Research on Earth in “extreme environments” could give indications of what to expect. However Earth still has its aerobic surface ecosystems that will influence subsurface ones.