Exploring Mars: Astronaut Versus Astrobot

It’s Sunday, May 25, and the $420 million Phoenix lander is blazing through the Martian atmosphere at 16 times the speed of sound. The half-ton machine deploys a parachute to slow its descent, but it is still coming in way too fast. Then, mere seconds before impacting on the Martian soil, the robot fires its retrorockets. Now gliding at just five miles per hour, Phoenix safely touches down on Mars and transmits a signal to the anxious mission controllers back on Earth. Success!

But even if Phoenix had smashed itself to smithereens on the Red Planet’s surface, at least no one would have died.

This basic ethical quandary underlies the continuing debate about sending fragile human beings to Mars. Current U.S. space policy calls for a manned mission as early as 2031, and it is probably inevitable that an Earthling will set foot on Mars someday. “It’s the human spirit for exploration,” says Walter Sipes, a NASA psychologist at Johnson Space Center in Houston, Texas. “When it comes to Mars, given time, we will be going there one way or another.”

Yet with recent advances in robotic exploration, some say that spending massive sums on a manned venture is foolhardy. Robotic missions generally cost about a tenth as much as human launches, and some estimates for a manned Mars trip range as high as half a trillion dollars. Advocates of manned spaceflight counter that robots severely limit scientific dividends by turning even basic operations like digging and soil analysis into colossal, week-long efforts. Even if a robot could someday match a human’s performance on the surface of Mars, some argue that for society to ultimately care about a Mars mission, it must be flesh and not metal that eventually does the job.

“The astronauts who go to Mars will come back to Earth as heroes,” predicts Sipes.

The Final Frontier: Risky Business for Humans

Though space is incredibly cold, completely airless and laced with radiation, all astronaut deaths have so far come from vehicle destruction. Two out of 124 missions involving the U.S. space shuttle have ended in disaster, resulting in 14 deaths since the spacecraft’s inception in 1981.

This failure rate of 1.6 percent is quite high when compared to other forms of transportation. For U.S. commercial flights from 1988 through 2007, for example, there were just 608 accidents (including intentional acts of terrorism) in over 185 billion departures, yielding a failure rate of three billionths of a percent, according to data from the National Transportation and Safety Board.

The aging space shuttle fleet is scheduled to retire in 2010 when it will be replaced by a new vehicle, christened Orion. Instead of riding alongside its booster rocket like the shuttle does, the Orion module will sit atop a newly designed rocket called Ares. This simpler orientation will keep foam or ice falling off the booster rocket from damaging Orion’s heat shield, which will be used during its reentry into Earth’s atmosphere. Such falling debris doomed Columbia and still endangers current shuttle crews.

In this way, the Orion spacecraft will represent a return to the Mercury- and Apollo-style capsules that splashdown in the ocean, then await retrieval by a Navy ship. Overall, Orion and Ares are expected to be ten times safer than the space shuttle, says John Stevens, the director of lunar architecture studies at Lockheed Martin, the company producing the Orion module.