American astronauts and NASA leadership prepare for a new mission with unlikely partners. Ellen gets in touch with an old friend.

Ellen is challenged by her new role. Margo’s allegiances are put to the test. Karen explores new opportunities—personally and professionally.

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.

Nearly 10 years have passed. Danielle and Ed attend a celebration, where things take a terrifying turn.

As NASA scrambles to prepare for the launch to Mars, Margo is confronted with a harsh personal reality.

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

The astronauts move quickly to build Martian bases.

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

Plans are made with interplanetary ramifications. Ed begins working with an unexpected partner.

Things start to go awry just as an important mission approaches a critical juncture.