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

Ed handles a trespasser. Ellen and Deke chart a new course without Mission Control.

Tensions on Earth and Mars come to a head.

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

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

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

A crisis in space puts the Apollo 24 and 25 crews in peril.

The resilience of Mars is put to the test.

Ed and the crew change Apollo 15's landing site after lunar ice is detected.

A commercial spaceflight company makes an announcement. The choice over who'll command the Mars mission leads to a shift in personnel.

NASA preps a Jamestown relief mission, while Karen waits for news at the hospital.

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

Plans to leave Mars are complicated by an unforeseen issue.

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

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

Nine years after the Goldilocks asteroid heist, Happy Valley has grown into a thriving colony. But an unsettling discovery threatens their peace.

Ed rallies Happy Valley's residents in support of one of their own. Kelly refuses to back down from an opportunity.

New Helios employees arrive on Mars as NASA undergoes major changes.

Eight years later, a new mission begins: Capture an asteroid. Aleida and Danielle are still haunted by events from the past.

The astronauts move quickly to build Martian bases.

A desperate group of Marsies tries to rectify a dangerous situation.

An accident on Mars strains relationships, while Miles embarks on a risky venture.

Alex takes Ed's advice and finds a new project to focus on: a job at Helios.

Chaos erupts on Mars following a shocking revelation.

Margo must lead a seemingly impossible mission. Danielle wants to return to the moon. Gordo grapples with life on Earth.

NASA is in crisis as the Soviets land the first man on the moon in 1969, the beginning of an alternate history.

Ed's reckless behavior at NASA shakes the foundation of the Baldwin family. Tracy attempts to readapt to life in space.

A discovery sends teams across Earth and Mars scrambling for answers.

Director von Braun opposes President Nixon's directive, with dire consequences.

Miles tries to make ends meet. Margo finds herself pulled into a dangerous situation.