Traveling light -- between planets
Wringing water out of the Martian atmosphere to make rocket propellant for a return voyage to Earth may sound like the stuff of a Grimm Brothers fairy tale.
However, like the dwarf who helped the miller's daughter become queen by spinning straw into gold, scientists are conducting research that someday may make space-refueling stations, and the possibility of interplanetary travel, a reality for all of us.
Using a technology known as in situ resource utilization, or ISRU, researchers are studying ways to mine natural resources on other planets. Their efforts could greatly reduce the cost to visit, and eventually live in, space. Current projects include efforts to produce rocket propellants from water in the air, and to mine aluminum for a special antenna that could collect solar energy and convert it into electricity for manufacturing on another planet.
ISRU technology has been around for several decades, but in recent years it got a boost from the Mars and other longterm missions.
"ISRU technology is available now, and it could be used to develop space in a big way, to the point where people could live in space independently," says Peter Curreri, group leader of the biological and physical space research laboratory at NASA's Marshall Space Flight Center in Huntsville, Ala.
Martian refueling stations could greatly decrease the payload weight, and thus the cost, of long-distance, manned space travel. About 10 percent of the Space Shuttle's weight is payload and fuel. It now costs at least $10,000 per pound to put a spacecraft into low-Earth orbit, according to the National Aeronautics and Space Administration. That's more than double the price of gold. Not carrying extra fuel also leaves more room for passengers and scientific experiments.
"It's the same as an airplane from Boston to Seattle being able to refuel in Seattle, rather than taking all the fuel for a two-way trip. If the plane is full of fuel, there's less room for passengers," says Adam Bruckner, professor and chairman of the astrobiology program at the University of Washington in Seattle.
Dr. Bruckner and his colleagues are experimenting on Earth with a material called zeolite 3A that could be an absorbent of water in the Martian atmosphere. Other types of zeolite are used on Earth to take impurities out of chemical flows or to dry up spills.
On Mars, the aim is to build a system in which ambient winds and fans would blow Martian atmosphere over a bed of zeolite 3A. Once the zeolite 3A is completely saturated with Martian water, it would be put into a sealed chamber and heated with microwave radiation to separate and collect the water. The zeolite 3A then could be reused.
The extracted water could be used for life support, or to create rocket propellant by separating the hydrogen from the water, and combining it with carbon dioxide to get methane and oxygen, which makes a potent fuel.
It could take as long as a year to accumulate enough water, but the cost savings over transporting fuel could be significant, Bruckner says. He adds that the water-extraction system could be set up and run remotely with robots. The technology isn't likely to be used on Mars for at least another decade.
Mr. Curreri of the Marshall Space Flight Center is looking at ways to get energy to planet surfaces. He and his colleagues want to mine aluminum to make a "rectenna," a receiver that can generate electricity from solar energy, beamed in the form of radio waves to the surface of Mars from a mother ship orbiting above. The energy collected would be stored in a power grid.
"This could power manufacturing on Mars," says Curreri, who will present a paper on his project at the upcoming October meeting of the International Astronautical Federation in France. Again, this technology is in the early research stage.
Nearer term, scientists are looking at ways to explore more of the Red Planet's surface. Scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., recently showed off an experimental, two-story tall beach ball called "the tumbleweed rover." Powered by the Martian breeze, which blows from 10 to 30 miles per hour, the rover would contain scientific instruments and be capable of rolling thousands of miles. By comparison, the 1997 Pathfinder traveled only a few hundred yards during most of its operations.
The tumbleweed rover, currently being tested in the desert, could be launched as early as 2009, according to Jack Jones, who heads its development effort at JPL.
The rover is made of the same rugged Tectran material used for the Mars Pathfinder's air-bag landing system. It will have recessed cameras at both ends of its axis, a magnetometer to sense shifts in tectonic plates, possibly a drill to take soil samples, and a spectrometer to tell what kind of soil it is traveling over.
Like previous developments in the space industry, several of the emerging technologies also have potential consumer applications. Bruckner of the University of Washington says his water extractor could be used to squeeze water out of desert air on Earth.
And Curreri says his rectenna technology could be applied to making power grids on Earth. However, both men say there are no current plans for such applications.
Perhaps the farthest-reaching ripple effect of the emerging space technologies is the promise of star voyaging for everyone.
A first step aimed at getting ordinary citizens into space is the X PRIZE, a $10 million prize for the first reusable spacecraft developed by private industry that can lift three humans into a sub-orbital altitude of 62 miles on two consecutive flights within two weeks.
The prize, run by a nonprofit foundation in St. Louis, is modeled after the $25,000 Orteig Prize that Charles Lindbergh won in 1927 for his trans-Atlantic flight.
About 21 teams have signed on for the prize, and about one-third of them already are building vehicles. The first successful launch is expected sometime in 2003, and the first sub-orbital commercial flights could come as early as 2005. Voyagers basically will take a one-hour trip just into the edge of space, spend about five minutes, and then return to Earth.
By 2008, more powerful spacecraft will be able to attain low-Earth orbit, says Peter Diamandis, chairman of the X PRIZE Foundation.
"There are only about 40 commercial launches into space a year now, including communications satellites," Mr. Diamandis says. "Here's an opportunity to create thousands of flights per year. People will get a glimpse of space travel."
He likens the effort to the early days of airplanes, when barnstormers would take people up for short plane rides just to get a taste of air travel. The prices for the space flights could run $50,000 to $100,000, he says.
It's just this kind of enterprise that could accelerate the advent of the star voyager. "The thing that will break space wide open will be the private sector, if someone figures out how to make a buck," says Bruckner.
The lure of space travel was so great that multi-millionaire Dennis Tito paid $20 million for his recent eight-day holiday in space. His trip renewed interest in civilian space travel. The US House of Representatives even piped up in July 2001 by introducing the Space Tourism Promotion Act of 2001 to develop affordable space travel.
All of this is exciting news to Brian Feeney, team leader of the Da Vinci Project in Toronto, Canada. Mr. Feeney will pilot his company's X PRIZE entrant vehicle.
The Da Vinci spacecraft will be lifted to 40,000 feet by a giant helium balloon, and then its engines will be fired for the rest of the trip to space. When it hits its peak altitude, a ballute parachute will deploy and float the craft back to Earth.
The craft uses some new technologies, including aerogel batting that insulates the fuel to keep it from burning off before take-off.
"We need to open peoples' minds to the possibility this can be done," Feeney says.
Mining natural resources on other planets may accelerate space exploration.