Gordo returns to space. Molly faces an upsetting new reality. Aleida confronts her first major hurdle at work.

The rivalry between American astronauts and Soviet cosmonauts intensifies as last-minute changes impact the Pathfinder mission plan.

Tensions between the U.S. and the Soviet Union reach an all-time high on the moon, throwing multiple missions into jeopardy. Season finale.

A surprise maneuver during the journey to Mars provokes desperate measures.

The race to land first on Mars brings together unexpected allies.

The astronauts move quickly to build Martian bases.

A joint mission brings about conflict between crew members.

After a sudden crisis, the Martian crews pull together.

Plans to leave Mars are complicated by an unforeseen issue.

The Martian crew debates how to save the life of one of their own.