NASA's second yearlong simulated Mars mission ends after 378 days in a Houston habitat

Four research volunteers have finished NASA's second yearlong simulation of living on Mars. In an article dated November 9, NASA said the crew of CHAPEA Mission 2 stepped out of the Mars Dune Alpha habitat at Johnson Space Center in Houston on October 31, after 378 days in a habitat with no windows and no real-time calls to family or friends, and that two weeks of post-mission evaluations and debriefs would follow.

This was a simulation on the ground, and nobody left Earth: the habitat stands inside a hangar at Johnson, according to NASA. Ross Elder, Ellen Ellis, James Spicer and Matthew Montgomery went into the 3D-printed habitat, about 1,700 square feet in size, on October 19, 2025. CHAPEA, short for Crew Health and Performance Exploration Analog, is NASA's series of missions in which four people live in isolation to stand in for a year on the Martian surface while researchers track their physical and behavioral health and how well they perform.

A year of simulated Mars

Over the year, the crew went on simulated Marswalks, ran robots, kept the habitat working, exercised and grew crops, NASA said. From inside the habitat they steered a drone and a rover by remote control, to survey terrain and to find or collect rock samples. They lived with limited supplies and with message delays to the outside of up to 22 minutes each way. A NASA podcast episode listed on the CHAPEA page has the crew discussing a simulated two-week communication blackout.

NASA's article sketches each volunteer's year. Elder, the commander and a test pilot, brought a US Air Force experimental test pilot's approach to the job and found the Marswalks and robotic exploration “uncannily similar” to taking part in a flight. Ellis, the medical officer and a US Space Force officer, helped organize biological sample collection for the health studies. Spicer, the flight engineer, was credited with keeping the habitat's systems running; he likened the year to life on a submarine, with the crew tracking supplies down to dish soap and respirator filters. Montgomery, the science officer, set up the habitat's 3D printing and brought his background in indoor agriculture to a seed-germination experiment using simulated Martian soil and a control.

Ellis said the main lesson she took away was that “a future Mars crew requires a highly integrated ground team.”

What NASA wants from the data

Grace Douglas, CHAPEA's principal investigator, said the research will help NASA balance risks to crew health and performance against resources, among them crew time, communication capacity and the design of food and water systems, according to the article. She also said many of the resource problems explorers face have parallels on Earth.

Sara Whiting, the project scientist, tied the data to NASA's planning for how astronauts will live and work at its Moon Base, which NASA describes as humanity's first lunar outpost, near the Moon's south pole. “This is really the now moment for this kind of data,” she said.

Two missions so far

NASA astronaut Jack Hathaway put the year in context, according to NASA's article: while the volunteers were inside, he flew a 237-day mission to the International Space Station and came home. In the same period, the Artemis II astronauts flew around the Moon, a flight NASA says set the record for the farthest humans have traveled from Earth.

NASA's article does not say when results from Mission 2 will be published. It says the post-mission evaluations are meant to help researchers interpret the crew's data together with what the four volunteers report about their experience.