Mission To Mars

IN THE LONG-AGO SUMMER OF 1969, when everyone who wasn't obsessed with Chappaquiddick or Woodstock was glorying in the triumph of the first manned moon landings, it was hard to find anyone who cared a whit about the Mariner 6 and Mariner 7 missions to Mars. Among other duties, the two flybys measured the Red Planet's ionosphere (the shell of charged particles high in the atmosphere). Their observations, and later ones, showed that shortwave radios, which bounce signals off this layer of ions, would work on Mars, and thus that 21st-century colonists could communicate with their base camp while exploring the cratered Martian terrain. No one noticed.

In 1976, when the two Viking landers confirmed that the Martian atmosphere was more chock-full of carbon dioxide than a bottle of seltzer, hardly anyone grasped the implication: that tons and tons of rocket fuel could be synthesized out of Mars's air, making traveling to and from Mars even easier than trips to the moon. In the 1980s, Martian meteorites revealed that the planet's soil contains lots of gypsum. No one pointed out that the find meant that astronauts on Mars could bake the gypsum, add some Martian water and iron-rich dust and thereby manufacture, on Earth's sibling planet, enough Portland cement to build an extraterrestrial Jamestown.

CEMENT PLANT ON MARS. Now there's a headline that should have been bannered, but it wasn't. Since Apollo, NASA had backed off from sending humans into space (for anything other than crewing the space shuttle), and certainly did not wax poetic about ham radio-wielding astronauts bounding across the cratered lowlands of Mars. After the first lunar landings, the public cared as much about moon shots as about the local Greyhound departures. Astronomers happily droned on about the ""Martian magnetosphere'' and other scientifically important but deadly dull finds; if they suspected that a particular discovery might pave the way for earthlings to fly to Mars, they kept mum. That doesn't mean, though, that no one was keeping alive the dream of Mars. The Mars Underground was.

For 15 years this informal network of space scientists and engineers has been quietly tracking discoveries from unmanned missions to Mars. Working for aerospace firms, universities and NASA itself, they'd tell anyone who would listen how earthlings, not robots, could fly to Mars, explore there and, one day, even build colonies there.

Now people are listening. It's too soon to apply for a mortgage on your own little acre in the Valles Marineris. But with the report last month that life may have gained a toehold on Mars 3.5 billion years ago, space scientists suddenly have good reason to look more carefully at those blueprints for getting humans to Mars. If there was once life on Mars, and especially if there is still life on Mars, then the cataclysmic climatic changes that turned the planet into a cold, barren desert forced organisms deep underground. The chances of robots' finding them are about the same as Antonio Banderas's striking out at a singles bar. Enter astronauts. ""Exploring below the Martian surface for water and living microorganisms,'' paleontologist Jack Farmer of NASA's Ames Research Center in California said last week at an ""astrobiology'' conference, ""may provide the most compelling reasons for carrying out human missions to Mars.''

And Robert Zubrin, the de facto chairman of the Mars Underground, can get us there on a consolidator ticket. In 1989, after President George Bush called for a manned mission to Mars, NASA costed it out: $400 billion, 30 years. A lot of money just to watch some spacesuits clomp around a crater field and plant a flag. So in 1990 Zubrin, then an engineer at Martin Marietta Astronautics, and colleague David Baker dreamed up a way to reach the planet on the cheap. The idea, as he puts it in ""The Case for Mars'' (318 pages. Free Press. $25), which will be landing in bookstores next month, is to ""live off the land.'' Off the air, actually. To carry enough propellant to get the Mars crew back to Earth, NASA's ship would have to be huge. And assembled in space. At a multibillion-dollar space station. Zubrin seized on the fact that Mars's atmosphere is 95 percent carbon dioxide, and balanced a few chemical equations. His conclusion: by reacting the carbon dioxide with hydrogen brought from Earth, you could produce enough liquid oxygen and methane fuel to fly back to Earth. You would even have enough to top off the tanks of some rovers and scoot around Mars for 500 days. It would cost $55 billion, according to NASA. But it would cost just $5 billion, according to Zubrin, if carried out not by the government but by private companies, lured by a $20 billion prize established by Congress.