Image courtesy ESA/IPMB

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Mars500 crew members Diego Urbina and Alexandr Smoleevskiy began their first "Marswalk" on Monday.

Image courtesy ESA/IPMB

Astronauts Walk on "Mars," Start Experiments

Three members of Mars500 project explore a sandy room.

Today, after months of anticipation, three brave astronauts set foot on Mars—or rather, a darkened, sand-filled room designed to simulate Mars.

The explorers make up half the crew of the Mars500 mission, a project designed to study the psychological effects of a year-and-a-half long, deep-space voyage to the red planet.

Since June 2010 six men—three Russians, two Europeans, and one Chinese—have been living in isolation in a 19,423-cubic-foot (550-cubic-meter) "spaceship" outside Moscow, doing maintenance work, conducting experiments, and trying to stave off boredom by playing Rock Band and reading the complete works of Gabriel García Márquez.

The crew is made up of volunteers, some with no real-life space experience but all with applicable skills, such as engineering and medicine.

Radio communications with project leaders are delayed to simulate the communications lag between Earth and Mars. Illnesses are handled by a crew member serving as the ship's doctor. The only food comes from packets of dehydrated meals.

Since the project started, scientists have been remotely studying everything that happens to the ersatz astronauts, from their internal bacteria to how they breathe at night. But now, after more than 250 days under the microscope, the astronauts are the ones performing the experiments.

The spaceship entered a mock orbit around Mars on February 1, and three of the astronauts entered a separate compartment meant to simulate a Mars lander. These crew members "landed" on Mars on Saturday.

Today the hatch opened for the first of three planned extravehicular activities, or EVAs, on the "Martian" surface.

Watch raw footage of the Mars500 crew's first simulated Mars walk.

The room that's standing in for Mars is designed to look like the surface around Gusev Crater, the landing site of NASA's Mars rover Spirit.

Over the next two weeks, the astronauts will collect soil samples, deploy magnetometers to study the simulated Mars's magnetic field, and plant national flags, said Oleg Voloshin, a press officer with Russia's Institute for Biomedical Problems, which is carrying out the experiment.

The astronauts who remain "in orbit" will drive a virtual robotic rover around Mars in something like an "advanced computer game," said Christer Fuglesang, director of the European Space Agency's contribution to the Mars500 mission.

Mars500 Crew Facing Gravity Adjustments

In preparation for landing, the three Mars walkers slept heads-down, to simulate the effects of going from zero-G to an environment with gravity—albeit a third that of Earth's, Fuglesang said.

The room itself won't simulate Martian gravity or weather, but astronauts will wear spacesuits during the EVAs that are about two-thirds lighter than real spacesuits, to preserve the illusion that gravity's pull is weaker on the faux red planet.

Fuglesang, a former ESA astronaut, notes that it's not easy to adjust to being in gravity after months of free-floating.

Though the Mars500 astronauts' feet have remained solidly on the ground the entire time, the transition is important to simulate, because "when you land on Earth, there are people taking care of you. There will be nobody on Mars to help them."

The Mars explorers will finish their experiments and pack up their samples by February 22. The lander will then return to the orbiting spacecraft—all without moving an inch—and it will be time for the six astronauts to start the roughly 200-day journey home.

The men on the virtual mission have held up remarkably well so far, Fuglesang added.

"One could have expected that there would have been confrontations, but it's been very good."

The return trip, however, is expected to be more psychologically grueling for the crew, with the excitement of the Mars landing behind them.