Another lunar leap? Humans visited the moon more than three decades ago. Now U.S. leaders want us to return

Science World, March 22, 2004 by Jeanna Bryner

In 1969, astronaut Neil Armstrong propelled himself into history books when he became the first person to set foot on the moon. It's been more than 30 years since Earth's dusty satellite (body that orbits a planet or star) had its last visitor. But this January, President George W. Bush announced a sweeping space plan in which Americans would revisit the moon and even set up a lunar camp.

SPRINGBOARD TO MARS

Why all the fuss over Earth's nearest neighbor? Top reason: It's a steppingstone for living on Mars, says planetary scientist Paul D. Spudis of Johns Hopkins University.

Scientists have a vision of building a platform in space from which humans could lift off for Mars. But it would take a lot of mechanical muscle to lug rocket fuel from Earth to the way station. "And it costs a lot of money to launch mass [fuel] up from Earth," adds Spudis.

Solution: Mine fuel from the moon. Since the moon is a lightweight--its mass (weight) is 81 times less than Earth's--its gravitational pull (attraction between two objects) is six times weaker than our planet's. This meager tug means it would take much less energy to transport rocket fuel from the moon to the space platform.

LUNAR FUEL STATION

Rocket propellant with the most thrust (push) is made of oxygen and hydrogen--mid there are plenty of these elements on the moon. According to Wendell Mendell, a planetary scientist at NASA, astronauts could get oxygen from lunar rocks. But not without a little work first. In moon rocks, oxygen is chemically bound to silicon, so geologists would have to separate the elements with high heat.

And with some effort, astronauts could extract hydrogen from water frozen solid at the moon's poles. Here the combination of hydrogen and oxygen molecules (H20) hides in the depths of large craters. The sun never reaches these so-called cold traps, so the water is locked up as ice, explains Spudis. To mine the ice's hydrogen for fuel, Spudis says astronauts could use electrolysis (passing electric current through a solution of charged particles) to split the elements.

REALITY CHECK

Does the President's plan mean you'll vacation on the moon's dimpled surface one day soon? Not so fast, says Howard McCurdy, a space historian at American University. Even if the $12 billion plan pans out within the next 20 years, you probably won't be beaming up there--unless you're a space scientist, He explains: "It would probably be for a research project, like people going to Antarctica to do research at the South Pole."

LANDING LOG

With only six moon landings to date, astronauts have plenty of spots left to explore.

1. Apollo 11: Sea of Tranquility 2. Apollo 12: Ocean of Storms 3. Apollo 14: Frea Mauro Formation 4. Apollo 15: Hadley-Apennine 5. Apollo 16: Plain of Descartes 6. Apollo 17: Taurus-Littrow

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SPACE MOON

TOXIC GLOW: A polycarbonate (plastic material in some sunglass lenses) helmet shields the face from the sun's harmful radiation (high-energy waves).

VITAL SUPPORT: There's no atmosphere (layer of protective gases surrounding a planetary body) on the moon. Tubes connected to a backpack carry needed oxygen to the astronaut.

KEEP YOUR COOL: Temperatures on the moon can get fiery during the day--up to 100[degrees]C (212[degrees]F), A system of water-filled tubes helps the body maintain a normal temperature.

BRACE YOURSELF: An outer layer of Mylar (similar to aluminum) shields moon walkers from tiny, flying space rocks.

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REACH FOR THE MOON

Check out these landmark liftoffs in lunar exploration--and what the future may hold.

TOUCHDOWN

July 16, 1969, Apollo 11: Astronauts Buzz Aldrin (above) and Neil Armstrong took the first steps on the moon. To mark the feat, they planted an American flag in the lunar soil.

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ABORT

April 11, 1970, Apollo 13: Nearly 47 hours after liftoff, an explosion in the craft's oxygen tank caused the crew to abort the mission and splash down safely in the Pacific on April 17.

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SMOOTH TREK

July 26, 1971, Apollo 15: The first of three missions to explore the moon's rocks had an added bonus: wheels! A lunar rover cruised at speeds up to 16 kilometers (10 miles) per hour.

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CLEAR VIEW

April 16, 1972, Apollo 16: Astronaut John Young set up the moon's first telescope. Reward: The moon lacks an atmosphere, so images aren't blurred like they are on Earth.

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ROCK'N'ROLL

December 7, 1972, Apollo 17: Humans dropped onto the moon's surface for the last time. Jack Schmitt, the first geologist on the moon, came face-to-face with a huge boulder called Split Rock.

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FUTURE SPACE CAMP?

According to the President's plan, astronauts could return to the moon's familiar turf as early as 2015, and even build a lunar dwelling.

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Did You Know?

* Many scientists think the moon formed 4.5 billion years ago when a Mars-sized body slammed into Earth. The impact caused chunks of rocks from both Earth and the impacting body to hurl into space. The debris orbited Earth and eventually assembled to form our moon.