March 20, 2000
NASA Thrusts Whitworth Scientist into Project Testing
If you think gas prices approaching $2 per gallon are steep, be glad you don't commute to work in the space shuttle.
It costs $10,000 per pound to launch payloads into space due to the high cost of rocket fuel and the inefficiency of existing chemical thrusters. But a Whitworth College professor will soon be working with NASA scientists on a new electric propulsion system that is 10 times more fuel-efficient than today's rockets and may make it practical to mount longer and more distant missions than ever before.
Richards Stevens, an assistant professor of physics at Whitworth, has been awarded a highly competitive fellowship that will allow him to spend 10 weeks this summer at a NASA laboratory working on a laser-testing system to improve the reliability and longevity of electric thrusters. The fellowship, sponsored by NASA and the American Society of Engineering Education, also will open doors for Whitworth students and faculty to participate in space science and research, Stevens said.
"The fellowship is designed to foster collaboration between NASA scientists and scientists at colleges and universities," Stevens said. "My research is in an area that is useful to NASA on this particular project, and I hope the relationships that come out of this collaboration will create funding opportunities to support our students and the growing research program at Whitworth."
Stevens will be helping NASA scientists develop a laser spectrometer for testing the rate at which key components in electric propulsion systems are breaking down. This is a problem that continues to plague electric thrusters despite the promise they have shown in NASA's recent Deep Space 1 mission and in several commercial satellite launches.
While traditional rocket thrusters create thrust by burning chemicals such as hydrogen, electric propulsion systems function by ejecting electrically charged particles out of a thruster at extremely high speeds. The process is relatively simple. An electrical power processing unit -- essentially a solar-powered battery -- is hooked up to the thruster chamber. The battery's positive electrode is connected to a porous plate in the center of the chamber while the negative electrode is connected to a similar plate at one end of the chamber. Particles of xenon -- a non-flammable, non-reactive gas -- are fed into the chamber. As the xenon ions pass through holes in the positively charged plate, they are attracted with great force to the negatively charged plate and are thrust out of the end of the chamber. The xenon particles are ejected at speeds greater than 60,000 miles per hour, creating 10 times the thrust of chemical propellants.
These thrusters are relatively weak, but they make up for it by running continuously. The little bit of force they generate adds up and, over the course of a year, can increase the speed of a spacecraft by up to 300,000 mph. The downside is that the continuous operation speeds up wear and tear on key components.
"The charged plates that generate the particle acceleration are essentially sand-blasted in the process," Stevens says. "That reduces the useful life-cycle of the thruster."
This is where Stevens comes in. His expertise in laser spectroscopy will help NASA develop a system for quickly testing the rate at which electric thruster components are breaking down. By shining a laser into the exhaust plume of a thruster and analyzing the wavelengths of light that bounce back, Stevens can detect and measure the amount of a particular material present in the exhaust.
"The idea is that NASA would like to test a number of different configurations in the thruster, but they don't want to have to wait two years to see which configuration, if any, actually slows down wear and tear," Stevens says. "Our technique allows us to determine right away whether a particular change significantly reduces the rate at which thruster components are breaking down."
Stevens is developing a laser spectroscopy laboratory at Whitworth to give his students the opportunity to tackle some of the same research challenges facing NASA scientists.
The electric thruster project is particularly appealing, he says, due to its potential to revolutionize space exploration. "If the moon turned lead into gold, it wouldn't be economically worth the effort right now because it costs so much to launch payloads into space," he says. "But if we can work out the kinks, ion propulsion systems re-write the rule book. Missions that were cost-prohibitive or impractical, such as sending humans to Mars, become possibilities. It's an exciting time and it's exciting to be a part of it."
Richard Stevens, assistant professor of physics, (509) 777-4508 or firstname.lastname@example.org
Greg Orwig, director of communications, (509) 777-4580 or email@example.com.