Scientists in Russia launched an ambitious Mars spaceflight simulation June 3 — one that will lock six volunteers away for a record-setting 520 days to practice every step of a mission to the red planet without ever leaving Earth.

The Mars500 project, a joint experiment by Russia, the European Space Agency and China, began  as the hatches to the mock Mars spaceship were shut at Russia’s Institute for Biomedical Problems (IBMP) in Moscow. Three Russians, two Europeans and one Chinese volunteer make up the experiment’s six-man crew.

The Mars simulation is expected to last until November 2011, with the crew relying on supplies of food, equipment and other essentials packed inside their mock spaceship. Only electricity, water and some air will be supplied from the outside, ESA officials said.

Each of the volunteers will earn about $99,000 for their participation in the 18-month endurance trial, which will simulate the 250-day flight to Mars, a landing and surface stay of up to 30 days, and then the 240-day trip back to Earth.

This Mars500 project follows shorter 105-day and 14-day simulations in the same Mars spaceship simulator in 2009. If successful, it will be the longest high-fidelity spaceflight simulation in history, outlasting the real six- and seven-month missions by astronauts and cosmonauts to the international space station.

The longest any human has spent in space on a single mission is 438 days, a record set in 1995 by Russian cosmonaut Valery Polyakov on the Mir space station. But if Russia, NASA and their international partners hope to one day send human explorers to Mars much longer missions will be needed.

“The duration of the mission and its focus on behavioral and physiological issues is really the benefit of this study,” American researcher David Dinges, a psychology professor at the University of Pennsylvania, said.

Dinges is leading the only American study attached to the international Mars500 project, an $800,000 investigation for the National Space Biomedical Research Institute to study the psychological effects of ultra long-duration isolation. In all, some 100 experiments are planned for the Mars500 crew during their mission.