News about Science, Technology and Engineering at Iowa State University

December 1997

News about Science, Technology and Engineering at Iowa State University

Shuttle bus to space

Shuttle bus deliveries of people and materials to a space station could change the extent and direction of the U.S. space program in the near future, and save money. Under NASA sponsorship, Ping Lu, an associate professor of aerospace engineering and engineering mechanics, is working on re-entry guidance and control systems for a half-scale prototype of a low-cost reusable launch vehicle. Dubbed the X-33, the vehicle takes off vertically like a rocket but returns to Earth like a big glider since it will have no fuel on the return trip. Lu's problem is to figure out how to guide and control the launch vehicle back to Earth for a safe landing on a runway.

Launch costs with current technology is $10,000 per pound of payload because the propulsion system is lost each time. The goal for the X-33 is $1,000 per pound of payload since the vehicle is completely reusable, single stage and low maintenance. Lu expects a turn around time for the vehicle to be a week. Flight tests for the X-33 are planned for 1999 and a target date for the real vehicle is 2005. Contact Lu at (515) 294-6956, or Marcia Martens Pierson, Engineering Communications, (515) 294-0259.

Satellite sticky tape

Larry Hanneman, chemical engineering professor, significantly changed the construction process of satellites by developing a new space-grade adhesive. He said the adhesive tape is pressed onto solar panel arrays, then a film backing is peeled away so that solar cells or optical solar reflectors can be stuck onto the top of the tape.

"Before this adhesive tape, the cells were bound by a sealant squeezed out of a tube," Hanneman said. "It was an extremely messy process and required a large number of expensive operations, such as trimming away the excess sealant."

Dow Corning owns the patent to the adhesive which is in commercial use, and several satellites in orbit were constructed using the special adhesive. Contact Hanneman at (515) 294-2540, or Mitch Mihalovich, Engineering Communications, (515) 294-4344.

Homegrown plastics

Plastics typically conjure up images of indestructibility, pollution for years to come and the need to separate products for recycling. Because of their environmental unfriendliness, researchers recently have been focusing on developing plastics that biodegrade. These plastics, like soy protein plastics, dissolve when immersed in water. The problem with soy protein plastics, though, is that they are too easily dissolvable, limiting their potential uses.

But that may change with the research of Joshua Otaigbe, assistant professor of materials science and engineering. Otaigbe has developed a new formulation of soy protein plastics that makes the material moisture resistant. The new formulation includes the use of polyphosphate fillers and silane coupling agents which results in soy protein plastics that are tougher in water and more rigid. But why make plastics that biodegrade slowly?

"We want greater control over the hydrolytic biodegradation of these materials," Otaigbe said. "We want materials that serve their function and then biodegrade in an environmentally friendly manner. With the new formulation, we've demonstrated greater control over the biodegradation process, and we have a material that is more rigid than previous soy protein plastics." Greater control over the material's biodegradation will allow several new uses for soy protein plastics, like in food packaging, medical implants and even sporting goods, Otaigbe said. Contact Otaigbe at (515) 294-9678, or Skip Derra, News Service, (515) 294-4917.

ISU physicists help build 'discovery engine'

Two Iowa State University physicists are part of an international team of scientists who will be designing and building detectors for the Large Hadron Collider, a high-energy particle accelerator, at CERN in Geneva, Switzerland. The Large Hadron Collider (LHC) is a next generation particle accelerator which physicists will use to explore some of the most basic building blocks in nature. CERN is the major high-energy particle physics laboratory in Europe.

"LHC will become the center of subatomic physics," said John Hauptman, an Iowa State professor of physics and astronomy, who is part of the U.S. collaboration. "I think the LHC very well could become a 'discovery engine' in particle physics well into the next century." Hauptman and ISU physics and astronomy professor E. Walter Anderson are part of an international team that is doing design work on a calorimeter that will be part of a detector on the LHC.

More than 550 scientists from 60 universities and six national laboratories will be working on two large detectors for the LHC. These detectors are instrumental in allowing physicists to see the aftermath of high-energy collisions between particles. It is from these collisions that the physicists can discern the basic building blocks of nature.

The U.S. Department of Energy and the National Science Foundation will provide $531 million over the next eight years for the LHC, which will become operational in 2005. Contact Hauptman at (515) 294-8572, or Skip Derra, News Service, (515) 294-4917.

Pure cooling power

Delicate instruments aboard an atmospheric research experiment are expected to operate longer and more efficiently, thanks in part to work by the Ames Laboratory's Materials Preparation Center. The MPC produced a high-purity lanthanum-nickel-tin alloy that is being used by the Jet Propulsion Laboratory, Pasadena, Calif. The material was successfully tested aboard a May 1996 space shuttle flight. It now will be used as the sorbent bed assembly in the cryo-cooler for the Long Duration Balloon Cosmic Microwave Background Radiation experiment in Antarctica. JPL is planning a test flight next summer, and will launch the balloon in December 1998.

A cryo-cooler works like a pump to get rid of heat generated by the satellite's instrumentation and its atmospheric equipment payload. The material used as the sorbent bed -- in this case, the lanthanum-nickel-tin alloy -- is charged with hydrogen to heat the material. A vacuum then sucks out the heat to create the desired cooling effect. The ongoing process of adding and removing hydrogen eventually degrades the material in the sorbent bed, weakening its cooling ability and exposing the instruments to greater levels of heat.

At JPL's request, the Materials Preparation Center fabricated a highly purified form of the alloy -- achieving a purity level 10,000 times greater than previous sorption materials. With less impurities, the alloy will remain stable for a longer period of time, said Larry Jones, MPC director. This in turn will allow the instruments to function longer and at consistent levels. JPL was so pleased with the MPC's work for the Antarctica project that they are requesting more of the alloy material for ongoing cryo-cooler research. Contact Jones, Materials Preparation Center, (515) 294-5236, or Susan Dieterle, Ames Laboratory Public Affairs, (515) 294-1405.