Space

Mars is the long shot of space

Crossing 35-million miles safely might be the least challenging aspect of putting astronauts on the planet.

Mars is a dangerous destination.

The two most recent arrivals, NASA's Spirit and the European Space Agency's Beagle 2, both experienced trouble in recent days.

Spirit's handlers spent several extra days figuring out how to get the rover's wheels on the surface, and Beagle 2's operators haven't heard from it since its scheduled touchdown Dec. 25.

Nor is this kind of thing new. In 2000, NASA lost two costly spacecraft: The Mars Climate Orbiter crashed on the planet's surface, and the Mars Polar Lander disappeared just before landing a few months later.

It probably will take years before the risks for humans come fully into focus - risks such as cosmic radiation, muscle and bone density loss, and the unknown psychological impact of three years in deep space.

Yet since President Bush announced his plans for a manned mission to Mars, some scientists have argued that the technological challenges of such a mission can be met with relative ease.

The carbon dioxide in the martian atmosphere, they say, can be converted into water for human use and into fuel for a return trip to Earth. The rocket science needed to build new vehicles to get there also exists.

"Humans to Mars may seem like a wildly bold goal to proclaim in the wake of disaster (the year-old crash of Columbia)," Robert Zubrin, an aeronautical engineer and author of The Case for Mars, testified before the U.S. Senate Commerce Committee a few months ago. "Yet such a program is entirely achievable.

"From the technological point of view, we're ready. All that's needed is present day technology, some 19th century industrial chemistry, a solid dose of common sense and a little bit of moxie."

Maybe a lot of moxie.

Cosmic radiation is one known hazard. On a round-trip journey perhaps three years long, radiation could damage human cells and cause cancer. Shielding against it has not worked to NASA's satisfaction, and so research continues.

Walter Shimmerling, a NASA radiation expert, said high energy particles from supernovas that exploded in our galaxy permeate interplanetary space.

"They are considered to be much more destructive biologically than common X-rays or gamma rays," Shimmerling told the Associated Press. "The particle acts like a very tiny bullet going through a living cell."

Scientists also worry about solar flares that can flood space with extremely energetic and destructive particles. To guard against this, solar satellites hopefully will give warnings, allowing Mars-bound astronauts to move to a safe room.

There are other concerns. NASA space station research has shown that some medicines don't maintain their efficacy in space. What happens if someone gets sick? What if someone dies?

And what of the psychological challenges? NASA's isolation research on the space station has shown that some astronauts don't handle it well. No human has ever undertaken a journey as uncertain and as dangerous as a trip to Mars, about 35-million miles away. There would be a lot of time to think during the eight-month flight.

Guy Fogleman, head of NASA bioastronautics research, said the four toughest problems that must be solved are space radiation, bone loss from weightlessness, the psychology of long-term spaceflight and remote medical diagnosis and treatment.

"There is a wide range of things we have to look at, and they all have to be managed (to) minimize the risk," he said.

"Take a lesson from our own pioneer past," Zubrin argued. "Travel light and live off the land."

In October, he described his plan, called "Mars Direct," to the Senate Commerce Committee. His general plan, which has been accepted by NASA, goes like this:

At a not too distant date, perhaps 2009, a heavy-lift booster would be launched from Cape Canaveral.

The upper stage of the rocket would detach from the spent booster, fire its engine and throw a 40-ton, unmanned payload on a trajectory to Mars.

This payload, the Earth Return Vehicle, would be built to bring astronauts back to Earth. The ERV would carry 6 tons of liquid hydrogen, a chemical processing unit, a few scientific rovers and a 100-kilowatt nuclear reactor.

Eight months after takeoff, the ERV would land on the Mars surface using a parachute and retro-rockets. Once the ship touched down, scientists back at Mission Control would deploy the nuclear reactor, to provide power for the chemical processing unit.

Inside the chemical processing unit, the tons of hydrogen brought from Earth would react with the martian atmosphere, which is 95 percent carbon dioxide, to produce water and methane.

The methane, fuel for the trip home, would be liquified and stored. The water molecules would be broken apart into hydrogen and oxygen; the oxygen would be saved for later use, and the hydrogen would be recycled through the chemical processing unit to generate more water and methane.

Two years later, in 2011, two heavy-lift vehicles would take off from Cape Canaveral.

One would carry a crew that would use the materials and fuel prepared by the 2009 mission. They later would fly home on the ERV.

The second heavy-lift vehicle is identical to the ERV launched in 2009. It would make water and fuel for a 2013 mission. In this way, each mission could prepare for the next, and a string of bases could be created.

"The science behind this is pretty sound," said Ken Debelak, associate professor and director of information technology for chemical engineering at Vanderbilt University and an expert in martian resource recovery. "The challenge is to send things up there to run autonomously, with no one there to turn the knobs, so that when a manned mission arrives, they will have what they need."

Zubrin said he prefers his Mars Direct plan, but supports Bush's plan to go to the moon first. A moon mission could be used to test equipment before a Mars mission, he said.

The Bush plan "legitimizes spending money, and that means productive work can begin," he said. "It says that our purpose is to explore space, not just experience it in low Earth orbit with the shuttle and the space station."

Rick Chappell, director of science and research communications at Vanderbilt University and former associate director for science at NASA's Marshall Space Flight Center in Huntsville, Ala., offered more measured support.

"Returning to the moon ... stretches us as a nation," he said. "It is something a great nation like America is capable of doing, and it is something we ought to do."

But, he said, "there is still a lot of technology to work through."

It has not proved easy to stop cosmic radiation with shielding, he said, "and it's not obvious how we will do that yet.

"Another issue is how we will keep the crew physically fit so they can walk and do work when they get there."

Exercises aboard a spacecraft can keep muscles relatively fit but cannot stop the bone loss that occurs in zero gravity, when the skeleton no longer bears weight.

One potential solution that has been talked about, he said, is attaching the Mars-bound spacecraft to its booster rocket with a tether, then spinning the two huge objects to create artificial gravity.

"Listen," he said. "There are lots of things we don't know, and to some people, things we don't know are deal breakers. But engineers don't think that way. They think there isn't anything we can't do. Nothing is impossible. We just have to figure out how to do it."

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