Proposal to send men to Mars fraught with risk

LONDON — Once again, an American president has offered a vision of humanity leaving the cradle of Earth and spilling out into the stars.

In 1961, President Kennedy challenged scientists to reach the moon by the end of the decade. In 1989, the first President Bush proposed a manned mission to Mars, an idea that was scrapped because of the cost.

Now his son, President Bush, is expected to reinvigorate America’s space program by reviving his father’s dream. This week, NASA will be told to work toward creating a base on the moon and putting people on Mars within two decades.

Although the plans are at their earliest stages, it is clear that the costs, and risks, would be astronomical.

The moon is just three days away; Mars is at least six months. Astronauts heading for the Red Planet would spend at least three years away from Earth, dependent on the water, air, food and fuel that they have brought with them.

Many scientists are skeptical about the need to put people in space. The most successful exploration of the solar system in the past few decades has been done by robots. Manned spaceflight is more about show business than science, they say.

The orbits of the planets mean that the best opportunities for traveling to Mars come every couple of years. In one proposal from NASA, a manned Mars mission would involve 12 spacecraft.

During the first launch window, three craft would carry an Earth-return vehicle, an ascent vehicle, a rover, nuclear-power stations, oxygen units, spare parts and a laboratory. The return vehicle would be parked in orbit, while the rest of the equipment would be sent to the landing site.

Two years later, three more spacecraft would send backup vehicles, more equipment and a crew of six or seven persons. The pattern of launches then would be repeated, allowing a second crew to replace the pioneers.

If the crew flew in 2014, they would take 150 days to reach Mars, spend 619 days on the surface and take another 110 days to reach home — total, about 2 years and five-plus months.

Aside from the dangers of living on Mars, where there is no air, where water is locked below the ground, where temperatures fall to minus 271 degrees Fahrenheit, and where dust storms scour the surface, the health risks of long-term spaceflight are huge.

No one has spent more than 13 months in space. The endurance record is held by Russian Sergei Avdeyev, who lived for 379 days on the Mir space station.

Without gravity, astronauts are vulnerable to kidney stones, immune-system problems and weakening of heart muscles. Bones can become so thin during a long journey across space that they spontaneously would snap on return to gravity. Away from Earth’s protective magnetic field, there also is the threat of cancer-causing radiation from cosmic rays and solar winds.

Even more difficult could be the psychological problems of spending nearly 30 months in a confined space.

The costs would be breathtaking. Some space scientists estimate that a Mars mission could reach $1 trillion. Missions to the moon would be far less dangerous. The last man walked on the moon in December 1972. After the initial excitement, the public lost interest in the Apollo lunar program. In all, 12 men have walked on the moon.

Skeptics say that trips to the moon and Mars might be a bigger white elephant than the International Space Station, still being constructed above Earth.

This year marks a golden era for robotic explorers. Britain’s Beagle 2 might have failed to call home from Mars, but NASA’s Spirit rover has sent back the most detailed pictures yet of the Martian surface. Meanwhile, Beagle 2’s orbiting mother ship Mars Express is about to explore the Red Planet in more detail than any other craft.

Early this month, the spacecraft Stardust collected dust from a comet’s tail, and later this year, Cassini will begin orbiting Saturn and send a probe to the surface of Titan, one of Saturn’s moons. Another space craft, Rosetta, also will be launched for an attempt to land on a comet for the first time.

Sir Martin Rees, the astronomer royal and professor of astronomy at Cambridge University, said, “With the advances in robotics and miniaturization, the case is tilting more strongly toward unmanned exploration. The case toward sending people into space is getting weaker.

“Manned missions will only make economic and political sense if costs come down tremendously and also if the American public is prepared to accept higher risks than they were in the case of the space shuttle,” he said.