Four Volunteers Complete NASA’s 378-Day Windowless Mars Simulation Without Live Calls Home

For 378 days, four volunteers lived without windows, outdoor sounds or real-time conversations with their families. Commander Ross Elder, medical officer Ellen Ellis, flight engineer James Spicer and science officer Matthew Montgomery completed NASA’s second yearlong simulated Mars mission on Oct. 31, 2026, after entering the sealed habitat on Oct. 19, 2025.

The duration was more than an endurance target. It gave NASA a controlled setting in which to examine how a four-person crew handled isolation, delayed communications, limited supplies and recurring technical work over a Mars-mission-length stay. The volunteers are now undergoing two weeks of evaluations and debriefings, so NASA has not yet released the experiment’s health and performance findings.

A house-sized test bed with Mars-like constraints

The crew lived in Mars Dune Alpha, a roughly 1,700-square-foot, 3D-printed habitat at Johnson Space Center in Houston. Its floor area was comparable to a medium-sized house, but its operating conditions were designed around the constraints expected in deep-space exploration rather than ordinary domestic life.

Communication with the outside world was delayed by as much as 22 minutes each way. That eliminated live calls home: contact with family and friends was limited to delayed email. The lag also forced the crew to work without the immediate conversational support available to astronauts in low Earth orbit, making planning and onboard decision-making more important.

The habitat’s lack of windows and outdoor sounds added another layer of separation. NASA identifies isolation and confinement as human-spaceflight hazards because crews traveling far from Earth must remain effective as a team for months or years. CHAPEA supplied a structured environment for collecting data on that problem without sending people beyond Earth.

The crew’s reflections show why the quality of the team is part of the system design. Ellis said that physical separation did not necessarily make her feel isolated because she could rely on her three crewmates. Montgomery put the point more directly: It’s really the people that make exploration possible. Spicer said he barely missed the continuous flow of news and social-media updates, while companionship and shared purpose helped sustain the group’s routine.

Maintenance, food and crew time were part of the experiment

Life inside the habitat was organized around work resembling the demands of a surface mission. The volunteers conducted simulated Marswalks and robotic operations, maintained habitat equipment, exercised and cultivated vegetables in a hydroponic crop system. Elder also described the preparation, airlock procedures and physical demands associated with the simulated surface activities.

Those jobs allowed NASA to study more than whether four people could tolerate a long stay together. Equipment maintenance consumed crew time, exercise competed with other scheduled tasks, and crop cultivation introduced another system requiring attention. Food, water, cleaning supplies and equipment all had to be carefully tracked and managed.

Spicer compared the experience with living aboard a submarine or boat, where limited space and supplies shape routine decisions. The crew monitored consumables ranging from dish soap to respirator filters. That kind of inventory work may appear mundane, but a deep-space mission cannot depend on quick resupply or a technician arriving from outside the habitat.

The communications delay also has implications for spacecraft and habitat design. Future crews will need useful decision-support systems and enough autonomy to diagnose routine problems while advice from Earth is still in transit. At the same time, mission planners must balance communications capacity, crew workload and the volume of information sent across deep space.

The results could reach beyond a future Mars spacecraft

NASA expects the collected data to inform tradeoffs involving food-system design, medical and behavioral support, crew time, communications bandwidth and other elements of long-duration missions. The work could ultimately influence spacecraft design, astronaut healthcare and mission planning for both lunar and Mars crews.

The immediate task is interpretation. Researchers will combine the crew’s debriefings with the physiological, psychological and performance measurements collected during the stay. Until that process is complete, the experiment’s most concrete result is operational: four people maintained a demanding technical routine for 378 days while cut off from sunlight, outdoor sounds and live family conversations.

CHAPEA project scientist Sara Whiting called this “the now moment for this kind of data” as NASA considers how astronauts could live and work at a proposed lunar outpost near the Moon’s south pole. The next design decisions will depend not only on rockets and habitats, but on what four people needed to keep working inside one for more than a year.

By David Whitaker — Associate editor for AMI’s aerospace and drone systems desk, translating flight systems, aircraft programs, spaceflight, and UAV developments into accessible technical stories.