Huntsville Times January 11, 2004
Marshall keeps generating ideas
Experts continue efforts while awaiting Bush plan
By Shelby G. Spires
While NASA and White House policy makers have been kicking around space destinations and science goals over the past few months, engineers at Marshall Space Flight Center in Huntsville have been working on ideas like making rocket fuel out of space rocks, ways to slow a spacecraft once it reaches a planet and developing better engines to cut trip times.
"The technology for space is there. It's been worked on for years in Huntsville as well as around the nation," said Charles Vick, a former U.S. Space & Rocket Center employee now with GlobalSecurity.org, a nonprofit group in Washington, D.C.
The technology "needs to be refined and improved, but it's there," said Vick. "We don't have to start from scratch to build a way to go to the moon. We just need the political will to use what we have."
New engines
President Bush this week is expected to outline a plan to send astronauts back to the moon, establish a lunar base and move into an advanced Mars exploration program. Space experts point out that Marshall, along with the rest of NASA, has been developing concepts and technology for this challenge for years.
The smoke and fire produced by rockets like the reusable space shuttle or Boeing's Delta IV, built in Decatur, come from burning chemicals. These fuels are about as efficient as they can be, and Marshall engineers want to find new ways to cheat gravity.
"We are getting about 98 percent efficiency from our chemical rockets, and it's just not enough to do the things we want to do," said Dr. Steve Rodgers, director of Marshall's Propulsion Research Lab. "In order to go into space or go to other (planets) there has to be a new way."
The 50-member research lab develops basic technology and then hands it off to other NASA programs to develop, either through more lab work and study, or by giving it to industry to pursue.
Rodgers' team will move into a new $30 million lab in the next couple of months. The new lab will consolidate work spread out over five other Marshall locations.
A major challenge is getting from place to place in the solar system quickly and efficiently. With today's rockets, it takes about three days to make a trip to the moon and more than six months to reach Mars
And space is dangerous. Cosmic radiation can fry spaceships. There is always the threat of being struck by a meteor. These are two more reasons why cutting travel time is important.
NASA is turning to Marshall labs to develop nuclear propulsion. These engines would be used once a craft is in space, not for launch from Earth. Nuclear reactors would drive electric engines and propel the ship. Also, the nuclear reaction could produce electricity for a spaceship.
Depending on the mission, a trip to Mars could take a matter of weeks with such a system, Rodgers said. "It all depends on what the mission is and what the needs are. I can't give a definitive answer, but I know we can reduce the travel time significantly," he said.
Spaceship brakes
Rodgers said getting to the moon or Mars quickly is a wonderful goal, but "you have to stop once you get there. How are you going to do that? That's a problem we have to solve," he said.
Astronauts can't slam on the brakes like motorists. Speed has to be bled off or counteracted. Thrusters would slow the rocket down to allow it to slip into orbit, but the extra propellant and engines take up weight.
Marshall scientists are developing a technique called aerobraking to counter the high speeds of new rocket motors. Aerocapture uses a planet's atmosphere to slow a spaceship down, said Dr. Les Johnson, manager of NASA's In Space Propulsion Project Office.
The space shuttle, the Apollo capsules and the recent Mars missions used the atmosphere's friction on heat shields to slow down from thousands of miles an hour. Then the craft lands like an airplane or a parachute pops out and slows it down for a ground or sea landing.
Aerocapture uses the atmosphere of a planet to slow down, but it does this by skimming the craft across the surface. A spaceship traveling to Saturn's moon Titan, or to a planet with an atmosphere would deploy a shell or perhaps a large balloon that would burn away as the spaceship skims across the upper atmosphere, Johnson said.
"Aerocapture is something we've never done before," Johnson said. "It's been talked about for a long time. It's our job to develop the technology so somebody could come along and use it. The benefit to aerocapture is that a vehicle would not have to take all the propellant to slow itself down ... it saves a lot of weight."
The aerocapture device is being developed for robotic probe missions like the Mars rover missions. But Johnson stressed a similar system could be developed for a manned mission.
NASA is spending about $10 million a year to develop aerocapture, and engineers expect to have test results on advanced designs by 2006.
Propulsion engineers are also developing solar sails to harness solar winds. Stars, our own sun included, send out high energy particles. These particles push on objects.
"We know that the orbits of satellites are affected by these solar particles," Johnson said. "We have to adjust their orbit. If we could put out a large sail on a robotic explorer, then those particles could be used to push the (probe) around."
The sail is not practical for manned missions because it would be too large to propel a large spacecraft, but Johnson seems encouraged it could be used for robotic missions.
Teams have tested boom hardware for solar sails at Goddard Space Flight Center in Maryland, and companies are working to develop lightweight material for the sail. Johnson expects the technology should be ready by 2006 for another office to pick up for a flight demonstration.
Johnson said the technologies could be adapted to Mars or lunar missions. A moon or Mars base would need supplies and the advanced work Marshall is doing in engines and other forms of propulsion, like the solar sails, could be used to haul unmanned supply tugs out into space.
"Length of time for supply ships isn't the same as a crew vehicle ... You could put the tugs in space and launch before the humans were launched and (the supply tugs) would be on the moon or Mars before a crew arrived," he said.
By doing this, NASA's main mission wouldn't have to haul supplies all the way to the destination.
Fruits of Mars
Another way to trim a rocket's waistline is to produce the fuel at the destination.
Marshall scientists are studying ways to "live off the land" by using this approach, said Dr. Peter A. Curreri, group lead at Marshall's biological and space research lab.
Curreri said a pound of equipment is expensive to launch into space.
"Roughly, it takes about $10,000 a pound to go to low Earth orbit," he said. "To put the lunar lander on the moon it was about $250,000 per pound. For the previous rover Sojourner (24 pounds) to be put on Mars it took about $750,000 a pound.
"If you are in space or on the moon or in orbit, then you have a tremendous weight requirement to get there in a launch vehicle from Earth," Curreri said. "On Mars, if you produce a pound of something you need, then you save.
"That capability is like gold, because you can take more with you from Earth that can't be found on Mars or on the moon."
Curerri's group is studying ways to take moon rocks or Martian soil and rocks and, through a chemical process, extract things like water or oxygen or hydrogen and turn those into rocket fuel or even use the water for people.
"You could send up an unmanned mission before and basically have a refueling truck when a manned mission lands," Curerri said.
The concept doesn't stop on the moon or Mars. Asteroids could be mined for valuable minerals for use on Earth.
"It's a theory, and there would have to be a lot of work, but we are going to need a way to travel, live and return from these places ... There are compelling reasons to go for research, science and commerce, but we've got to figure out a way to get there that won't generate (large) costs."
Robot eyes
The Bush plan reportedly would begin with robotic missions, like the current Mars rover missions, before explorers are launched.
Richard Hoover, an astrobiologist at the National Space Science and Technology Center in Huntsville, said robotic probes would be wonderful trailblazers "but humans have to follow. We can't stop with the machines," he said.
"I have great hope that at some point in the not-so-distant future there would be a manned Mars mission. We can learn a great deal from robotic missions, but we learn so much more from the human brain."
As an astrobiologist, Hoover leads researchers to places like the Arctic ice caps and the desert in search of life. Scientists believe life forms that can live in extreme temperatures and atmospheres, like a volcano or salty lake, may be found on other planets.
"Life will probably take a different form elsewhere, and we have to know what to look for here," Hoover said. "These probes can show us where to look, but I think a person has to do the looking."
© Copyright 2004, Huntsville Times
