Research subjects who have lived with limited human contact since January recently completed an experiment.

The six, four men and two women, lived near the top of a volcano on the Pacific island of Hawaii.

They agreed to stay in a small, restricted area as part of a study to learn about the mental and emotional effects of a long term space mission.

The six people lived and acted much like astronauts would on an eight-month long visit to the planet Mars.

The American space agency NASA provided money for the experiment. Information gathered in the study will help NASA choose individuals and groups with the right qualities for a trip to Mars.

Life as an astronaut can be stressful

Individuals who are able to deal with long-term space travel need to have special qualities or traits. They need to be able to deal well with isolation, pressure and danger for up to three years on a trip that would take them far from Earth.

The six research subjects were isolated from other people on a large flat plain near the top of Mauna Loa, the world's largest active volcano. The area is about 2,400 meters above sea level and has thin, dry air.

During the experiment, the subjects wore space suits like those worn by astronauts and traveled in teams whenever leaving their living structure.

Researchers called the dome-shaped living space a habitat. It is about the size of a small house.

The kinds of foods available to the research subjects were limited. They ate mostly freeze-dried or canned food during the experiment.

All communications between the "crew members" and outsiders were given a 20-minute delay, increasing the sense of isolation. Twenty-minutes is the time it takes a radio signal to travel from Mars to Earth.

Study is part of the effort to take humans to Mars

The mission was the fifth in a series of six NASA-financed studies at the University of Hawaii habitat. It is called the Space Exploration Analog and Simulation, or HI-SEAS.

Laura Lark was the team's information technology specialist. She thinks a manned flight to Mars is a reasonable goal for NASA.

Lark described the project in a video message recorded in the dome. "There are certainly human factors to be figured out, that's part of what HI-SEAS is for," she said. "But I think that overcoming those challenges is just a matter of effort. We are absolutely capable of it."

In the experiment, researchers used games to study human behavior. The crew members played games designed to measure their ability to work together. Games also helped measure their ability to deal with pressure or stress. The crew members also kept documentation of how they were feeling.

In addition to activities, members of the team wore sensors that measured voice levels and how near they were to others in the living space.

Kim Binsted, a professor at the University of Hawaii, was one the lead investigators in the study. She said the sensors could record if people were avoiding one another or if they were close to each other in an argument.

"We've learned, for one thing, that conflict, even in the best of teams, is going to arise," Binsted said. "So what's really important is to have a crew that, both as individuals and a group, is really resilient, is able to look at that conflict and come back from it."

Another part of the study was to test ways to help the crew members coped with stress. When they felt helpless, they could use what the researchers called virtual reality devices. These could show the team members images of a seaside getaway or something else.

Other countries have performed studies on the effects of long-term space flight. The researchers in Hawaii, however, say their project provides an environment most like Mars.

The area on Mauna Loa is covered with hard, red volcanic rock.

The crew-members were required to carry out studies of the rocky surface, make maps and care for their habitat. The living space had a laboratory, cooking area and bedrooms with little room for anything else.

After the experiment was finished, food was the first thing on the mind of the six astronauts. They gladly ate a feast of tropical fruit.

I'm Mario Ritter.

Mario Ritter adapted an Associated Press story for VOA Learning English. His report includes material from the experiment's website. George Grow was the editor.

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traits – n. qualities that make a person different from another

isolation – n. the condition of being alone or separated from others

dome – n. a structure or part of one shaped more or less like a half sphere

challenges – n. things that are difficult to do

resilient – adj. able to return to health or normality after something bad

cope – v. to deal with problems and to try to find solutions to them