HILO >> Six volunteers have begun a four-month stay in a small dome on Hawaii’s Mauna Loa volcano to gauge the effects of long-time confinement in space missions.

The volunteers will largely be confined to a 1,000-square-foot space during the next round of the Hawaii Space Exploration and Analog Simulation research project.

The goal of the study at the 8,200-foot elevation is to see what problems arise when people are confined to small spaces on long missions, such as a Mars expedition, the Hawaii Tribune-Herald reported Tuesday.

“We’re going to stress them,” said Kim Binsted, the project’s principal investigator. “That’s the nature of the study.”

Volunteers began their mission Friday.

Binsted said the mission could provide insight into what’s called the “third-quarter syndrome,” which refers to the psychological wall people can hit on long missions.

“In the first quarter, they are excited,” Binsted said. “They celebrate halfway, and then they realize they are not close to going home yet.”

Two later phases will follow, one lasting eight months and the other for one year.

The volunteers each have a science background. They will have research projects to fill their time, including one focusing on propagating plants on a Mars mission and another looking at applying 3-D printing to remote medicine.

Group efforts will include mapping nearby lava flows while volunteers are wearing their spacesuits. The project aims to test how well the volunteers will work together.

In the first mission at the dome last year, volunteers focused on food preparation during long space voyages. The volunteers created a recipe book that has been made available to the current volunteers.