After nearly a year and a half, the crew of a European mission to "Mars"—including these two, pictured testing Russian space suits last summer—returned home this morning, stepping out of their capsule to much fanfare in Moscow.
In reality, the six men never left Earth. They've spent the last 520 days in a mock spaceship in the Russian capital as part of an experiment to study the psychological effects of deep-space voyages.
The Mars500 crew members were physically cut off from the rest of the world and faced with a simulated 20-minute communications delay, to mimic the expected conditions of a real human trip to Mars.
The "astronauts" had plenty to do during their voyage: In addition to reading and playing video games, the crew had to conduct experiments on their minds and bodies, repair equipment, and even respond to simulated emergencies-including performing CPR on a mannequin.
IMBP and the European Space Agency partnered on the Mars500 project, which aimed to simulate a real mission to Mars as closely as possible. One possible difference: The Mars500 ship was spacious, with a private room for each astronaut and a sit-down kitchen.
Still, the 520-day isolation experiment is the longest simulated space mission so far. NASA's longest, for example, lasted about a hundred days. IMBP and ESA "kind of jumped in and did the 500-day study," said Joe Kosmo, a senior project engineer who's worked on NASA's Desert RATS project. The U.S. program tests equipment-but not human psychology-during simulated space missions in Arizona.
Kosmo argues that, before testing human resilience on isolated missions, space programs should first test and perfect the technology that will get astronauts into deep space.
Photograph courtesy Stephane Corvaja, ESA
Right at Home?
The all-male Mars500 crew included three Russians, an Italian-Colombian, a Chinese, and a French citizen—Romain Charles, pictured in the module's kitchen.
Charles, an engineer and quality specialist for the French company Sotira, was the second crew member to exit the ship upon the conclusion of the mock Mars mission.
The Mars500 mission was packed with experiments for the crew, with researchers curious about what was happening to the men's saliva, digestive systems, and muscles, among other things.
Crew member Diego Urbina tweeted regularly—with a delay, to simulate relaying messages from a traveling ship to a command center on Earth—about drawing blood, running on treadmills, and sleeping while hooked up to various devices. (Related: "Human Guinea Pig to Blast Off With Space Shuttle.")
Although they weren't actually in a microgravity environment, the Mars500 crew also performed the types of strength and aerobics training that might help prevent atrophy in space.
Photograph courtesy IBMP
The Mars500 crew members took part in a Chinese-designed experiment to test the effects of a closed environment on the body, as measured by traditional Chinese medical techniques.
Above, one man uses a device for photographing crew members' faces and tongues, so that researchers will be able to analyze characteristics such as the color and quality of his natural "tongue fur," or coating.
Romain Charles stands near edible plants growing inside the Mars500 module.
Current research suggests that a journey to Mars would require more than canned and freeze-dried food. For one thing, most food taken to the International Space Station either spoils or loses its taste after a year.
In addition to using a small greenhouse, the Mars500 crew tested a "salad machine" (not pictured) that simulated the effects of zero gravity on plants by slowly spinning them as they grew.
Photograph courtesy IBMP
Even the boss had to be a lab rat: Alexey Sitev, commander of the Mars500 mission, is seen sleeping with an electrode wired to his head.
Researchers worry that human circadian rhythms—deprived of natural cycles of darkness and light—would be disrupted, leading to stress and psychological dysfunction. The Mars500 crew therefore had to "collect" data even while asleep.
During the mission's Martian landing, three crew members entered a separate capsule meant to represent a lander, then simulated travel to the surface of the red planet.
Crew members Diego Urbina and Alexandr Smoleevskiy donned space suits and explored a sandy room designed to look like Mars. The men planted flags and studied and retrieved mock Mars rocks before returning to the lander and rejoining the main ship.
A Mars rover, driven by remote control, explores the sandy surface of the Mars500 "landing site."
The room was designed to resemble Gusev Crater, the real-life landing site of NASA's Mars rover Spirit. When the crew explored the room, they wore space suits that are about two-thirds lighter than real suits, to preserve the illusion of a weaker gravitational pull on the red planet.
The Mars500 crew relaxes with a video game last Halloween.
Such distractions, as well as the spaciousness of the ship, mean that the experiment hasn't really proven humans are ready for a trip to Mars, according to the science blog io9. A real-life mission would mean much smaller living quarters and no big home theater setups.
But the crew and mission managers call Mars500 a success: "I am convinced," ESA director Jean-Jacques Dordain said in a statement, "that this experience is the starting point of much bigger adventures."