A GREEN PROPELLANT
Using a safer, environmentally friendly chemical to boost rockets

After the February 1, 2003, space shuttle Columbia accident, a report by the Columbia Accident Investigation Board concluded that a piece of insulating foam damaged Columbia's wing, causing the shuttle to break apart during re-entry.

In addition to the cause of the accident, investigators were also greatly concerned with any effects the accident might have on the people and environment in the areas where the debris was scattered. One such concern was the possibility of contamination from the shuttle's propellant, hydrazine, a toxic, flammable liquid. According to the EPA, exposure to hydrazine can cause irritation of the eyes, nose, and throat, dizziness, headaches, nausea, pulmonary edema, seizures, and coma.

The incident, as well as many others, has prompted the military to look at more environmentally-friendly alternatives to propellants like hydrazine. One such propellant is hydrogen peroxide, which is the focus of LSU Department of Chemical Engineering and Minerals Processing Research Institute Professor Ralph Pike.

The Minerals Processing Research Institute and Sierra Engineering, Inc. of Carson City, Nevada, were awarded a grant from the U.S. Army Space and Missile Defense Command for a study of the thermal decomposition of propellant grade hydrogen peroxide. The substance they are working with is 98 percent hydrogen peroxide, nothing like the version used to clean cuts and scrapes, which is only 5 percent hydrogen peroxide.

One significant advantage of using hydrogen peroxide in rockets is that it leaves no pollution behind. As it decomposes, hydrogen peroxide separates into water and oxygen. The water evaporates due to the heat from the combustion chamber, leaving behind water vapor and oxygen gas, which poses no harm to the environment.

As part of their experimentation, Pike and his research associates, Casey O'Quin and Nick Richard, monitor the rate of decomposition of hydrogen peroxide. Suspended from a fiber optic filament, a drop of hydrogen peroxide is heated to 2,500 degrees Fahrenheit. Once heated, the hydrogen peroxide begins to decompose and the team uses a high-tech camera to video the drop at 30 frames per second. A computer then breaks down each frame and calculates diameter changes in the drop, which allows them to measure the mass of the drop.
Hydrogen peroxide provides a great advantage over other propellants because it requires less equipment and parts on a rocket. It also allows the concentration of stabilizers and corrosion inhibitors to be focused on safer handling of the hydrogen peroxide.

Sierra Engineering will take Pike's research and begin building trial models, which, after extensive testing and assessment, will eventually be incorporated into space vehicles and land-based systems.

ON THE WEB:
LSU Minerals Processing Research Institute
LSU Department of Chemical Engineering
U.S. Army Space and Missile Defense Command
U.S. Environmental Protection Agency

from Winter 2005