GRC NEWS RELEASE 99-65 News Release 99-65 For Release: August 12, 1999 Pam Caswell (Phone: 216/433-5795) Lori J. Rachul (Phone: 216/433-8806)

Rocket Fuels Researchers Suspend Frozen Hydrogen Particles in Helium

Rocket fuels researchers at NASA Glenn Research Center have made for the first time tiny particles of frozen hydrogen suspended in liquid helium. This is the first step toward new rocket fuels that can revolutionize rocket propulsion technology needed for getting off the Earth. In the experiments, small amounts of liquid hydrogen were poured onto the surface of liquid helium. The liquid hydrogen was at a temperature of 14 kelvins (minus 435 degrees F), just above freezing point; and the liquid helium was held at 4 kelvins (minus 452 degrees F), or just above absolute zero. As the liquid hydrogen fell toward the surface of the helium, small, solid hydrogen particles formed and then floated on the surface of the helium. The suspension will be used to make futuristic atomic fuels that take advantage of the chemical recombination of atoms into molecules. "Atomic fuels will make possible rockets with liftoff weights one-fifth that of today’s or with payloads three to four times more massive," said Bryan Palaszewski, Glenn principal investigator for the experiment. Using atomic fuels could reduce or eliminate on-orbit assembly of large space vehicles, thereby eliminating multiple launches and years of assembly time and making flights to all parts of the solar system less expensive and more practicable. In atomic fuels, atoms of very active elements would be stored in a medium that prevents their recombination. Solid molecular hydrogen is a promising medium for storing and keeping atoms separate because it becomes solid at temperatures just a few degrees above absolute zero, where atomic activity due to heat is at a minimum. Helium, in turn, is the ideal medium for creating and holding the solid hydrogen particles because it remains liquid below the freezing point of hydrogen. In the rocket’s reaction chamber, or engine, the fuel would warm, and the atoms would be freed. In less than an instant, they would recombine into molecules, and temperatures would go from 4 to 2000 kelvins (minus 452 to 3140 degrees F). Both hydrogen and helium would instantly vaporize and shoot out of the engine at tremendous speed, propelling the rocket forward. Details about the behavior and characteristics of the particles are described in a paper presented at the U.S. Air Force High Energy Density Materials Meeting in Cocoa Beach, FL, in June of this year. The advanced fuels experiments are part of Glenn's continuing efforts to advance the state of the art of propulsion technology. The experiments were conducted under the auspices of the NASA Advanced Space Transportation Program (ASTP), led by NASA Marshall Space Flight Center, Hunstville, AL. Current research is underway with an extensive team that includes researchers from Glenn, Marshall, the U.S. Air Force, the Department of Energy, universities and industry. An image of solid hydrogen in helium is available upon request. # # # 99-65 -end-