Mars or Bust

I. THE VISION
The spaceship that will launch six astronauts to Mars is a single, spare room just fifteen feet wide. Known as the Crew Exploration Vehicle, the tiny module sits, like a tuna can with a jet pack underneath, on top of three enormous booster rockets that will blast it into orbit. Once in space, the craft will sidle up to a transport vehicle, a two-story container the size of a smallish suburban house, one cylinder stacked on top of the other. The bottom floor is expected to look like a dorm room -- common space, kitchen, bedrooms no bigger than closets where the astronauts can latch their sleeping bags into the wall with hooks, so they don't float off in the night. On the top floor there will be a small area for scientific experiments and a cockpit to steer the damn thing. The astronauts will be confined to this cramped space, like teenagers under an insanely strict curfew, for six months going away, and for another six months coming back.

This is not some science-fiction scenario dreamed up by an idle, pot-addled kid who has read too many novels by Arthur C. Clarke. Last fall, to almost zero publicity, NASA released an actual plan for the Crew Exploration Vehicle. Ever since 2004, when President Bush declared a manned mission to Mars to be the "new course" of America's space program, engineers and scientists at the agency have spent their days in an extended scramble, rearranging their projects and priorities. The spaceship is still tentative, nothing but broad guidelines for the contractors who have signed on to design the thing. Before there were plans, NASA engineers talked about the Mars craft in the hushed abstraction of metaphor, called it the Winnebago -- as in, "how much stuff can we fit in the Winnebago?" Now that there is a design, their conversations have begun to edge into the fantastic. Respected scientists -- men who are normally fastidious, blunt, dead serious -- are suddenly full of Star Trek-size dreams of exploring distant galaxies and populating other planets.

"Are we going to stagnate, or are we going to push out against a frontier? Those are the options. What we at NASA are trying to do is push that boundary." This is the astronaut Ed Lu talking, a physicist who has been in Earth orbit three times, a guy who has flown to the space station and the scientist who first explained the underlying physics of solar flares. A compact man with an awkward, lopsided grin, he's sitting in a room at the Johnson Space Center that's normally used for press briefings. It looks like a junior high auditorium -- small stage, scratched-up floor, cheap wooden chairs. But for Lu -- a man of science not given to hyperbole -- the future is palpable and scary. The Earth is doomed to destruction. Humanity's only hope is to head into outer space, looking for safer ground. And our best chance is the closest planet in the solar system: Mars.

"The long-term survival of the human race will depend on our ability to master the art of spaceflight," Lu says. "It may be because of an asteroid's impact, or it may be because we deplete the resources on Earth. But human civilization is going to have to expand outward."

Human civilization is going to have to expand outward. The fantasy of barren, freezing, sand-whipped Mars has inspired outlandish schemes for the past five decades, ever since the father of the space program, Wernher von Braun, concocted a plan to send an armada of ten spaceships on a heroic scientific expedition to the Red Planet. When the president announced that NASA would send astronauts to the moon by 2020 as practice for a manned landing on Mars, the idea was dismissed as election-year grandstanding, a laughable attempt to cast Bush as a figure of history. "An unserious proposal," predicted The Washington Post, "succeeding merely in sounding big and capturing newspaper headlines."

But for an agency still reeling from the explosion of the space shuttle Columbia, the Mars mission offers something bigger than headlines: a chance to recapture its faded glory. The president's advisers titled the plan the Vision for Space Exploration. The engineers and astronauts who believe in it refer to it -- in quiet, mythic terms -- as the Vision. "In the long run, a single-planet species will not survive," says NASA director Mike Griffin. "One day, I don't know when, but one day, there will be more humans living off the Earth than on it."

Impressed by such leaping aims, Congress has endorsed the Mars mission as NASA's sole goal, even though the effort is expected to take fifty years and cost at least $500 billion. To pay for the mission, the agency is threatening to cancel other, less flashy projects -- like the Hubble telescope and the Voyager satellites -- that have resulted in some of America's most valuable and groundbreaking research.

At this stage, however, the Vision seems less a scientific undertaking than another of the president's faith-based initiatives. In order to succeed, NASA will need rockets that haven't been developed, robotic devices that have barely been contemplated and technologies that are, at best, just an inspired idea in an engineer's head. The Apollo missions to the moon took three days each way; even if the trip to the Red Planet is timed for the moment when Earth and Mars swing closest to each other in their revolutions around the sun, the voyage will take two-and-a-half years: six months out, eighteen months on Mars, six months back. While there, the astronauts will be expected not only to create a self-sustaining human community for themselves -- one capable of producing their own food, water and energy -- but to build a permanent base for future missions. To survive, they will likely need a whole new way of generating energy and synthetic materials that have yet to be invented.

"People don't have any idea how hard this is," says Robert Bishop, a NASA veteran and chair of aerospace engineering at the University of Texas. "We're talking a completely different scale of difficulty than anything we've ever done before. If we do make it work, it will be the greatest engineering accomplishment of all time."

No one knows yet whether the Vision will mark a new epoch for humanity or one of the most wild-eyed and foolish boondoggles of all time. No one is sure whether it will prove to the world that America remains capable of the most extraordinary feats, or whether it will squander vital resources in a meaningless show of ostentatious symbolism. But whatever the cost -- and whatever the outcome -- the mission has become, in the words of one influential space insider, "the defining focus of NASA."

"It's actually happening," says George Abbey, former director of the Johnson Space Center. "It may take half a century, it will probably cost hundreds of billions of dollars and it will be one of the most complicated and challenging things we've ever done. But the human race is going to Mars."

II. FADED GLORY
It's great to be back on earth," says Leroy Chiao. Last spring, the astronaut returned from a six-month trip to the space station with the Russian cosmonaut Salizhan Sharipov. A month into the trip, thanks to a NASA miscalculation, the two men suddenly found themselves running low on food. With a resupply mission weeks away, their rations dwindled to the point that they were subsisting mostly on desserts and hard Russian candies. By the time Sharipov and Chiao plunged back to Earth in a tiny capsule, their knees pinned against their chests, they had each lost nearly ten pounds.

Thirty years ago, the adventure would have made Chiao an international superstar; twenty years ago, it would have retained a touch of the epic. But when Chiao gave a speech about his mission at the Johnson Space Center in Houston, only a handful of people attended, most of them NASA employees and their children. The main emotion in the room was not awe but relief -- Thank God we didn't crash this time.

The Vision comes at a critical moment for NASA. For years the space agency has been suffering from an accomplishment deficit so profound that even its most routine trips are cause for alarm. The seven astronauts who died in the Columbia, their shuttle burning up in an iridescent flash over Texas, had been sent to space on a mission that was desperately mundane: One of their experiments aimed to determine how well urine mixes with paint in space. "The problem," one NASA official says, "is the public can't seem to get a handle on what it is exactly that we do." Once the engine that defined national achievement -- Americans are the kind of people who can go to the moon! -- the agency now seems like an aging jock, always looking back to the good old days when the cheerleaders swooned, when grade-school teachers kept Neil Armstrong snow globes on their desks.

Even Johnson itself seems like a fading anachronism, decades shy of what we think of as the Space Age. Since the manned space program began, the center has been its symbolic seat, home to Mission Control and the base where astronauts live and train. But Johnson now looks like some outdated vision of the future, a Tomorrowland gone to seed. The campus rests on a huge plot of land on the southern edge of Houston, surrounded by miles of cheap roadside joints -- a pawnshop, a low-rent nail place, the Neil Armstrong Deli. Just about all of the buildings were built when the center originally opened forty years ago. The workers here are mostly government contractors -- golf shirts and khakis, big bellies, bulgy plastic ID cases dangling around their necks -- and everyone seems to be done with work by 4:30, punching the time clock.

The astronauts themselves are mostly guys who went to schools like the University of Washington and Cal State Polytechnic, proud nerds and family men who spend their weekends in the garage, idly tinkering with circuits, trying to figure out a better control panel for the cockpit. You get the sense that such efforts might help. NASA's technology is disappointingly low-tech: The simulators for the space station and shuttle are the same ones the astronauts used twenty years ago, full-size mock-ups that look -- with all their curved white parts -- like something Darth Vader would walk through. The instrument panels resemble those on a small plane, only with more screens. And when the astronauts practice weightlessness, they do it, wearing space suits, in what is basically a twenty-foot-deep swimming pool.

NASA's engineers have seized on the Vision as a chance to reverse this sad decline. For the first time in years, there is the hope that something truly awe-inspiring might still happen here. The prospect is so big, so historic, that those leading the effort grope for words to describe it. "Like the mission to the North Pole," one scientist says. Bigger. "Like Columbus crossing the Atlantic," an astronaut adds. Bigger. "Like the first fish that climbed out of the sea and onto land," an engineer declares.

III. GETTING THERE
The problem isn't that getting to Mars is conceptually complex. It's that the trip will be conducted so far from Earth that there is no fail-safe system -- no rescue mission can be sent out in time, and, should anything go wrong, Houston will be hard-pressed to fix it from afar. If one gear freezes or the navigation system slides off course, the astronauts could end up stranded on a planet 35 million miles from home.

Bishop, the aerospace engineer, has a PowerPoint presentation he likes to show that details the results of the several dozen robotic missions to Mars launched during the past thirty years. The record is stunning: Fully two-thirds of the missions have failed -- busted launches, spectacular crashes, satellites drifting off into space, so much abandoned junk. If a robot crashes into the Martian surface at hundreds of miles per hour, NASA writes off the loss and chalks it up to science. But Congress and the public will not tolerate a $500 billion manned mission that turns deadly. "If we spend fifty years building this thing," Bishop says, "NASA simply can't have it crash and explode."

The first obstacle is simply getting the Winnebago off the ground. None of the rockets that NASA has now is nearly powerful enough to lift the Crew Exploration Vehicle and still have enough fuel left over to propel it all the way to Mars. So the agency has drawn up plans for a "heavy-lift launch vehicle" on the scale of the Saturn V, the Seventies-era rocket that was the most powerful ever developed. But even a rocket of that magnitude probably wouldn't have enough power to send the Winnebago all the way to Mars. So NASA's experts are contemplating a "multistage mission," in which the spaceship will be blasted into Earth orbit in three or four parts, each from its own separate launchpad, and then attached in orbit -- a tricky task that can require an astronaut to leave the capsule and manually guide each stage of the vehicle into its proper place. And even this multipart launch wouldn't be big enough to get everything to Mars at once, so NASA is planning for two or more Winnebagos -- one to deliver the astronauts themselves, and others to deposit "packages" containing equipment and life-support structures. To power the crafts, engineers are studying a variety of approaches -- a nuclear device, solar panels or even a magnetic bubble around the ships several miles wide that would be driven through space by solar winds.

Beyond the physics of rocketry and propulsion, Mars presents a more amorphous set of challenges: how to keep the astronauts alive, let alone healthy and happy enough to perform the complex physical and mental feats that will be demanded of them. From the moment a person enters a zero-gravity environment, the human body begins to wither away. Muscles, including the heart, atrophy in space because they don't need to work as hard -- it takes much less of a push to propel an astronaut through a spaceship than along a sidewalk on Earth. Bone density declines too -- at a rate of one percent per month in space, compared to twenty percent over a lifetime on Earth -- because atrophied muscles need a less robust frame. Atrophy isn't much of a problem on the space station, where astronauts remain in zero gravity for the entire trip. But at the end of the six-month journey to Mars, the astronauts will be dumped back into an environment with gravity and will need strong muscles in order to survive.

Dozens of doctors -- from the Johnson Space Center to medical schools around the country -- have been enlisted to help solve these problems. The astronauts will be kept on a steady regimen of biphosphomates, drugs that keep molecules of calcium from breaking off and forming kidney stones, a common problem in space travel. NASA is also developing a completely new kind of weight-lifting machine designed to simulate gravity in a zero-g environment, where even a scrawny biologist can bench-press a 500-pound barbell with his pinkie finger. The new machines require astronauts to pull a pump out of a vacuum, which can be adjusted to suck in at greater or lesser degrees of intensity, working different muscle groups. The astronauts will also work out on an exercise bike that uses magnetic filings to create resistance and a treadmill with a large harness that pulls down on their shoulders and hips when they run. Such machines are crucial to strengthen the heart -- which, just like the body's other muscles, weakens considerably in space because it doesn't have to work as hard to pump blood. "If you've got someone who's spent a year in space pumping blood at zero g's, and then all of a sudden you've got to get out on the Martian surface and start pumping at 0.38 g's, then that's a problem," says Jeff Jones, a flight surgeon in charge of exploration medicine at Johnson.

Even more dangerous is the highly increased risk for cancer. The Earth's atmosphere shields us from X-ray and proton radiation from the sun, but astronauts will have only the relatively thin walls of the Winnebago to protect them. To reduce their exposure, NASA is working to build the spaceship with less iron and steel. Such metals contain neutrons that get kicked loose by radiation and absorbed by the human body, where they can cause cancerous tumors to form. Instead, NASA may fashion the ship's hull with some of the same materials -- mostly a class of Kevlar-like substances -- that are used to help keep bombers invisible to radar. Since these synthetic materials contain dense packs of electrons and protons, astronauts will be bombarded with fewer neutrons -- but not by much. "Even with the best shielding we can do, there's still going to be an elevated cancer risk for astronauts going to Mars," says David Robertson, the head of space medicine at Vanderbilt University. "We're going to have to watch these guys very carefully when they get back."

And then there are the emotional hardships -- things that cannot be engineered away. Because there is no precedent for the Mars mission, psychologists at NASA are studying explorations of earlier times -- sea voyages to new continents, dog-sled trips to the Arctic Circle -- to see what contributed to their success or failure. The best way to ensure that the men and women aboard the Winnebago are able to tolerate the conditions, says Duane Ross, the head of NASA's selection board, "is to pick the astronauts we send very, very carefully." Ross gets an absurdly qualified applicant pool each year -- 20,000 competing for twenty spots. But he doesn't look for raw intelligence or macho swagger -- he looks favorably on "campers, believe it or not. People who have experience being outside in the woods on their own, and maybe have to solve some problems there, to improvise. The astronauts we send to Mars will likely have two characteristics: They will have visited a bunch of other countries, so we can be sure they can get along with folks from other cultures, and they'll have had a lot of experience camping."

IV. BEING THERE
Mars will be a raw and unwelcoming campsite. The surface is barren -- a great Gobi Desert, stretched over a sphere. There is no water. The air, with high concentrations of carbon dioxide, is unbreathably toxic. The temperatures, which average 81 degrees below, would freeze a person to death; the planet is constantly subject to vicious windstorms, more powerful than Hurricane Katrina, that whip across the landscape, kicking up dust clouds that block out the sun. "This," concludes Bishop, "is not a terribly hospitable place."

The first challenge will be to bring the Winnebago to a peaceful landing on Mars. Bobby Braun, an earnest young engineering professor at Georgia Tech, has dedicated his entire career to figuring out how to bring hurtling objects to an interstellar stop, setting down softly on their destinations rather than crashing into them. For him, helping to brake the Crew Exploration Vehicle is the coolest and most difficult project imaginable. The most likely method, he says, involves retro-rockets that fire backward and a very large parachute to slow the approach. To conserve fuel, Braun would prefer to use only a parachute, but given the weight of the craft, he says, "the parachute would have to be so big you probably couldn't get it all unfolded before crashing into the ground."

Once the Winnebago enters the orbit of Mars, the astronauts will have to transfer to a small landing vehicle, which they will pilot to their base on the planet. Because the astronauts will be exhausted and weak once they arrive, the craft will have to rely on robotic landing systems to bring the craft to within a hundred feet or so of several "packages" of supplies and equipment, which will have to have been dropped earlier, without sustaining any damage. And both the packages and the astronauts will have to be dropped right next to a scientifically interesting spot. All of this requires that the robotic landings be precise enough to hit within a hundred feet or so, several times in a row, adjusting for the ferocious winds and sandstorms. But existing landing systems only aim for an area the size of Manhattan, and, Bishop acknowledges, "a lot of times we miss that."

If the astronauts manage to land safely, they will find a planet that provides absolutely nothing that can sustain life. That means they must bring almost everything they need with them: a habitation module, an all-terrain vehicle, food and supplies for eighteen months, scientific facilities and equipment, a drilling apparatus that can probe the Martian surface for extractable water, as well as materials to build a permanent base. The astronauts will likely need a small nuclear device to provide power. And they will need some form of superior anti-corrosive coating -- a kind of mega-Rust-Oleum, which hasn't yet been developed -- to cover everything they bring, protecting it from the constant Martian sandstorms. The hope is that technologies now being developed will enable the Mars base to assemble itself, with minute pivots unfolding a compacted, origami-like design into a full habitat, so that the living quarters will be ready by the time the astronauts arrive. "We're certainly not there yet," says John Connolly, an aerospace engineer at Johnson. "But this is one of the things that we're going to try to figure out on the moon: how much of the base can be constructed robotically and how much will really need human hands."

To provide food -- and recycle the carbon dioxide exhaled by the astronauts into oxygen -- astrobiologists at NASA have been working to perfect plants that can be grown in microgravity. One pioneer in this field is Nigel Packham -- a skinny, intense Englishman who recently spent three months living in a self-contained biological habitat, trying to figure out what problems the Mars crew might encounter. Packham and three other scientists recycled oxygen through hydroponically grown plants and water through chemically cleaned human waste. The team wore "Mars or Bust" buttons, and the experiment was such a success that by the end they didn't want to leave. For food and for recycling oxygen, Packham says, "the most efficient plant, interestingly enough, turns out to be dwarf wheat." So the trip to Mars might include several trays of that plant; the rest of the oxygen conversion will be done by chemical reactors, which put carbon dioxide and water through electrolysis to yield breathable air.

Then there's water. Astronauts consume between three and four gallons of water each day in space, an amount far too heavy to blast off from Earth. To solve the problem, Don Holder, a NASA engineer, spends most of his days at the Marshall Space Flight Center in Huntsville, Alabama, trying to figure out how to extract water from urine in space. In his best system so far -- likely to be the model used on Mars -- urine is collected in a cylindrical tank kept on a closet shelf on the spaceship. The cylinder rotates, keeping the urine close to a precisely calibrated heater, which boils off the water and collects the steam in an elaborate system of fans and filters. What's left behind, Holder says, is a "nasty, black, sludgy brine." A writer from Wired who taste-tested water extracted from his own urine reported that, though "definitely not Evian," it was "certainly more palatable than many light beers I've had."

When they aren't struggling to survive on Mars, the astronauts will be expected to test the planet's soil and atmosphere, seeking to understand the conditions under which life can emerge -- and whether human beings can establish a viable colony on the planet. For the past two years, that job has fallen to Spirit and Opportunity, the robotic rovers that continue to crawl around the Martian surface, plunging metal arms into the soil and testing its chemical composition. The probes discovered what their designers hoped they would: precipitates that indicate that what are now rocks on dry Mars were once soaked with water. But the robots work slowly, inching along, dumbly dipping their probes into the surface. Humans -- who can scan the landscape and know where best to search for any micro-organisms that might remain -- can cover in a day what takes robots six months. "The fantasy," says Laurie Leshin, director of sciences and exploration at NASA's Goddard Space Flight Center, "is that some astronaut could pick up a rock and flip it over, and in an instant we'd realize that we're not alone in the universe."

V. GETTING BACK
After eighteen months on Mars digging up soil samples, drinking their own piss, and living in cramped quarters each and every day with five other people from whom there is no escape, the astronauts will probably be more than ready to get home.

They may also be stark raving mad.

The record for consecutive time spent in space is 379 days -- less than half the time a Mars mission would require. The best evidence for what happens to the human psyche during long, lonely stays in space comes from the Russian space program, which has sent its cosmonauts up for extended stays on the Mir Space Station. In 1997, a series of mechanical failures onboard led to what The Washington Post called the "psychological erosion" of commander Vasily Tsibliyev; the cosmonaut refused to complete his assigned tasks and yelled at his doctor at Mission Control when she tried to help. To calm the fragile crew, an American astronaut played Apollo 13 on his computer monitor, translating the dialogue into Russian himself.

And that was a relatively short mission. To keep the Mars astronauts from losing it, a psychological-operations team at Johnson will monitor each astronaut and adjust his schedule based on his personal profile, precisely calibrating how much time he works in teams, conducts experiments on his own, exercises, relaxes and sleeps. But nobody knows whether such tricks will be enough to keep the astronauts from going stir-crazy. And video communication with their families -- a key psychological stabilizer on the shuttle and space station -- will be difficult: As the astronauts near Mars, the signal will operate on a twenty-minute lag.

In October, the National Academy of Sciences released a report that raised another problem: sex in space. Two and a half years, after all, is an awfully long time to go without getting any. Nobody yet knows what the composition of the crew will be -- five men and one woman? three gay men? all single? married? -- or whether they'll be attracted to one another. But as the study points out, any combination seems perilous. If there's no screwing, it could be a pretty grumpy couple of years. And if there is any interstellar sex, or even an unrequited crush, the situation could spiral out of control. This point was underlined last year, when a male cosmonaut on the space station tried to kiss a female Canadian colleague. She, quite literally, ran the other way. Mission Control had to remotely lock the door to the Canadian's quarters so the Russian couldn't get in, and wait for everyone's tempers to cool.

Assuming the astronauts haven't killed one another in a jealous rage after eighteen months on Mars, getting home will require them to fly up to the Winnebago and blast out of orbit. What they will need, at that point, is a whole lot of rocket fuel. But because fuel is so heavy, there is no way the astronauts will be able to bring enough fuel with them to get back. That means that NASA will somehow have to extract, refine and develop fuel on the moon or on Mars. The plans currently being developed by aerospace engineers border on the ludicrous. One calls for NASA to refine rocks on the moon, use the material to build arrays of solar panels on the surface and then beam the energy to Mars by microwave. Another would have NASA send teams of robotic rovers to scour the entire moon for a few scattered isotopes of helium-3, hyperexplosive elements that have been deposited there by solar winds and, if gathered and stuck in a nuclear reactor, could not only power the Mars mission but solve Earth's global energy needs.

A more modest project would use a combustion engine powered by a small nuclear generator to break down rocks found on the moon or Mars into basic elements, like hydrogen and carbon, that could then be refined and used as fuel. But even its designers admit that the plan is nothing more than speculation; mining fuels in space has never been tried, and no one has yet designed a contraption capable of standing up to the fierce Martian climate.

VI. THE COST
The entire undertaking, experts say, involves far more than building zero-g refineries or designing more powerful rockets: Putting humans on Mars will require a quantum leap in both science and industry. The technical challenges are so daunting, in fact, that many of the leading scientists responsible for getting us from here to there doubt that it is possible. "What worries me most," says Gentry Lee, a veteran of the Apollo missions and the lead systems engineer at NASA's Jet Propulsion Laboratory, "is that I don't think that we're smart enough to pull it off right now."

The biggest problem, Lee says, is that America doesn't have the engineering brainpower it did in the days of Apollo. Kids aren't studying engineering anymore, and the minds we imported from China and India in the 1990s are now returning home in pursuit of more lucrative opportunities. "I've got to put the dozen best systems engineers in the country around a table sometime soon and figure out what questions we've got to answer in order to get to Mars," Lee says. "We don't have a dozen engineers that good."

Lee is famous at NASA -- he has had a hand in most of the great engineering breakthroughs of the past three decades. But the agency's most breathtaking accomplishments have come not from the Jocks -- the astronauts and flight engineers eager to explore new worlds -- but from the Nerds -- physicists and climatologists and other science geeks who sit quietly at their desks, sorting through data from weather satellites and high-powered telescopes. The irony of the Vision is that the very scientific programs that have made it possible for us to contemplate a manned trip to Mars are rapidly being cut in order to pay for it.

Though few outside the physics labs realize it, the last decade has been a golden age for astronomy. NASA has built unmanned probes that have photographed distant planets, finding evidence of ancient seas on Mars and ice-covered water on Europa, one of Jupiter's moons. It has used its massive space telescopes to make startling new discoveries about how galaxies have formed and evolved. It has confirmed data suggesting that the universe is largely composed of a mysterious force we know only as dark energy, which is probably causing the cosmos to expand at an ever-faster speed, like a roller coaster in a steep plunge. And it has documented Earth's fragility, tracking the warming of the atmosphere and oceans. "It is hard to imagine an individual, group or agency in the whole of human history that has had such a good run, and has done so much to advance human understanding," says Joel Primack, an astrophysicist at the University of California-Santa Cruz who led a panel of the American Physical Society that issued a report critical of the Mars mission.

None of these scientific achievements would have been possible without data collected by NASA, which can construct telescopes and satellites so powerful that no university could afford to build them. But despite claims to the contrary by the Bush administration, it is becoming increasingly clear that the agency cannot fund both exploration and science at the same time. To pay for a manned mission to Mars, NASA will have to scrap virtually every other scientific project, no matter how profound or far-reaching it might be -- a decision that could have potentially disastrous consequences. "NASA has been the spark for all of these magnificent breakthroughs," says Burton Richter, a Nobel laureate in physics at Stanford. "If we cut science funding now, we're stopping some of the most profound advances in human understanding in half a century dead in their tracks."

With the exception of the astronauts and engineers involved in the Mars mission, few scientists think the Vision is a particularly good idea. If you polled scientists, most would say there is "no real scientific justification for a manned trip to Mars," says Joseph Alexander, senior staff officer of the space studies board at the National Academy of Sciences. The Congressional Budget Office concluded that the Mars mission will cost more than the $104 billion that NASA has projected through 2018, forcing the agency to cancel more promising experiments. Abbey, the former Johnson director, says the price tag will ultimately run as high as $500 billion. "The projections they've put together for budgets are pipe dreams," confirms one NASA insider. "You're talking about a project on the order of $500 billion, and right now they're budgeting $1 billion per year for it. Sooner or later, the Vision will either have to swallow much of the science funding or it will die."

Abbey believes in a manned trip to Mars, and he and others at NASA have suggested a simple way out of the funding dilemma: turn the Vision into an international mission like the space station, with contributions from Europe, Japan, China, Brazil and Canada. "My hope," says Lee, "is that just as Apollo was an unmistakable and universal symbol of American dominance in the Cold War, the Mars mission can become an equally powerful symbol of international cooperation for a new age."

Unfortunately, the Bush administration is not exactly known for playing well with others. To pay for the Mars mission, the Vision calls for decommissioning the space shuttle -- a move that has antagonized the Europeans, who have spent millions developing experiments that depended on the shuttle. Indeed, the European Space Agency threatened last spring to join forces with Russia and Japan to develop their own lunar spacecraft. Without the shuttle, says one retired NASA official, "we can probably forget about the Europeans as a meaningful partner."

VII. THE OBSESSION
One of the ironies of the Mars mission is the curious alliance it has forged between the Bush administration and the strange, underground world of Mars obsessives, between the governmental suits and the flat-out weirdos. Long before the president laid out the Vision, a ragtag bunch of amateur astronomers, apocalyptic kooks and Babylon 5 fans had been urging mankind to fulfill its destiny by heading out into the solar system. Getting to Mars, they insisted, would be a monument to human greatness, a defining achievement of civilization. Their leader -- the man who has emerged as the most vocal advocate of the president's mission to Mars -- is Bob Zubrin.

Zubrin is a born obsessive whose career has proceeded less from design than from a series of successive twitches. In his teens, he invented a three-player chess game. In his twenties, he taught science and math in New York public schools. In his thirties, having gone back to college and become an aerospace engineer, he designed rockets for the defense contractor Martin Marietta. And in 1996, he published a wacky text, The Case for Mars, detailing his plans for setting up a civilization on the planet. "Do we choose to make the efforts required to continue as the vanguard of human progress, a people of the future?" he wrote. "Or will we allow ourselves to be a people of the past, one whose accomplishments are celebrated only in museums?"

The book, astonishingly, became a best seller, and Zubrin capitalized on the interest by founding the Mars Society. What the world needed, he decided, was a testing ground, a place where he and his fellow Mars-heads could live for weeks, pretending they were on the Red Planet and conducting mock scientific missions in spacesuits and keeping careful notes on how much water they consumed and how many times they used the bathroom. It would be, in Zubrin's fevered imagination, a kind of scientific vanguard for a project that NASA had not even begun to plan. So Zubrin raised $1 million from his fellow Mars freaks and built Mars on Earth.

The plan was to set up a Mars habitation station on Devin Island in the Canadian Arctic, where the weather and topography approximate that on Mars. In 2000, Zubrin arranged for a detachment of Marine Corps reservists to para-drop the outpost at the selected site and hired a Canadian construction crew to assemble it. But the reservists managed to break the equipment while dropping it, and the hired crew deserted. "It was shaping up to be a complete disaster," Zubrin recalls.

Then, with the brief Arctic summer coming rapidly to a close, a Mars Society member named Frank Schubert took charge. Schubert, a former guitarist for Devo, assembled a team of teenage Inuit boys from a nearby village to build the station. Amazingly, the plan worked, and the station has been staffed by the society's members ever since. The project has been such a success that NASA has sent astronauts and scientists to Mars on Earth, because it offers the closest thing to a simulatable Mars. Zubrin has consulted with senior NASA officials, and the agency's engineers take his calculations seriously. When you talk to mission planners about what the possibilities are for getting to Mars, they all mention Zubrin.

"What the Vision has done is amazing," Zubrin says. "A year ago I was debating the best way to go to Mars in front of a dozen graduate students. Now I'm testifying before Congress. We're much closer than we have been before to our goal -- to taking the first steps toward extending human civilization to other planets."

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Zubrin is an acerbic and difficult man, incapable of small talk, who faults NASA for "screwing everything up so far." But like all starry-eyed prophets, he is able to evoke a true feeling of awe, a sense that great things are possible. "Earth is not the only world," he says. "There are billions of other potential homes for life. The first of these is now within our reach."

The first of these . . . Even less zealous advocates of the Vision insist that it could ignite an unsurpassed era of technological advances and scientific discovery. "We may well have people living on the moon," says Griffin, the man in charge of the entire space program. "We may have people living on the moons of Jupiter and other planets. We may have people making habitats on asteroids. We've got places that humans will go -- not in our lifetime, but they will go there. I know that humans will colonize the solar system and one day go beyond."

For now, however, even getting to Mars and back remains a long shot. If the mission comes to seem senseless to too many members of Congress, if its costs run wildly beyond control, if the spaceship takes off and crashes, or if Mars proves inhospitable to life, then the entire undertaking could go down as one of the most costly and foolish wastes of resources in human history. NASA is well aware of the risks. On January 26th, in a ceremony at the Johnson Space Center, the agency commemorated the twentieth anniversary of the Challenger disaster. In one of history's most searing demonstrations of the limits of human engineering, seven astronauts died when the shuttle blew up seventy-three seconds after liftoff -- bound for a mission that was many times simpler than the Mars voyage and whose mechanics had been practiced many times before.

"Spaceflight remains the pinnacle of human challenge, an endeavor just barely possible with today's technology," Griffin acknowledged in a statement prepared for the ceremony. "It is an enormously difficult enterprise, made more so by the fact that we are human beings and flawed. The losses we commemorate today are a mute and terrible reminder of the sternness of the challenge -- and of the awful consequences of our flaws."

Then, as the survivors of the shuttle astronauts looked on, the widow of the Challenger's commander laid a wreath.