When NASA begins launching astronaut teams on 800-day missions to Mars, one of the greatest survival tests these explorers will face is the inevitable alienation they'll experience with their remoteness from Earth and the harshness of the frozen Red Planet.

After rocketing halfway around the solar system for 180 nights, these astronauts will start the first of 500 days on the Martian surface observing a cocoa-colored dusk fade into a star-saturated nightfall. Earth, 400 million kilometers away, will appear as just a twinkling blue diamond in the skies. The astronauts will have never felt so alone.

But NASA thinks it has an answer to the psychological challenge of interplanetary isolation. While aerospace engineers are designing the Ares rockets to be deployed in the Mars missions, a more starry-eyed contingent at NASA is testing networking and virtual reality technologies that they think will connect the first wave of Mars pioneers with their families, friends and colleagues back on Earth, in a 3-D virtual world cut from the mold of Second Life or World of Warcraft.

"We want to help our remote explorers 'phone home' in a way that lets them sit around a dinner table with their family, help their children with homework and analyze the latest findings with their Earth-bound peers," says Jeanne Holm, chief knowledge architect at NASA's Jet Propulsion Laboratory.

The initiative is the latest in the space agency's enthusiastic push into virtual worlds. In May, NASA set up its own island in Second Life to enable online collaboration on technology projects, and the agency is working to create 3-D simulations of the orange-red deserts of Mars, so astronauts can experience the Red Planet before going there.

"Virtual worlds will play a key role in returning to the Moon and exploring Mars, says Jessy Cowan-Sharp, who helped create NASA's CoLab island in Second Life.

But an interplanetary virtual world faces the seemingly intractable limits imposed by the speed of light. When on diametrically opposite sides of the sun, Mars and Earth are separated by 20 light-minutes; when closest, the planets are still four light-minutes apart. That's a long ping time, and jacking into a virtual world over a radio link of that distance would be like diving into a vat of very thick molasses.

NASA can put a man on the Moon, but can it conquer connection lag?

Daniel Laughlin, learning technologies project manager at NASA's Goddard Space Flight Center, is optimistic. He's studying earthbound "immersive synthetic environments" for use in the space program, and he says NASA is trying to figure out how to work around the interplanetary lag problem.

While e-mail messages would seem like an obvious solution, and one easily in reach of current technology, it's not good enough, Laughlin says. Forcing the Mars astronauts to rely solely on e-mail communication with family and friends could underscore, rather than erase, the vast gulf between them. In contrast, the immediacy and intimacy of synthetic worlds would make astronauts feel at home.

"If we were meeting in Second Life or World of Warcraft to chat, we would both have the sense of being in the same place overlaid on our sense of physical location," Laughlin muses. "The experience encodes into our memories as if we were in the same place."

If NASA's virtual world gambit seems like a pipe dream, there's no doubt that astronauts traveling to Mars, or returning to the Moon, will enjoy a wealth of tech communications options that the Apollo crews couldn't have imagined.

Chris McKay, a planetary scientist at NASA Ames Research Center, says that with high-resolution videocameras, podcasts and web forums, the first Mars invaders could stage the ultimate reality show, with some becoming super-icons back on Earth.

Just knowing that their every move is being watched by a rapt audience at home could help the Mars voyagers find the strength to solider on in the face of "long-term conditions of isolation, privation and psychological stress," says Robert Zubrin, author of The Case for Mars and founder of The Mars Society.

"The psychological boost enjoyed by Mars-bound astronauts of knowing that they are 'golden people,' celebrated as heroes by millions on Earth, cannot be overstated," says Zubrin.

NASA's Laughlin, though, is committed to giving astronauts a more interactive experience. They might even be able to tap the internet from Mars to order Christmas gifts from e-Bay or cards from northpole.com for delivery to friends still on their home world, he says. Or they might download the latest singles from iTunes or e-books from Amazon.com.

Of course, with a single interplanetary TCP handshake clocking in at 12 to 60 minutes, the Mars mission will probably want to use One-Click.