Saturday, August 22, 2009

The technology

The technology described in this story is a spin-off of basic materials science research. It began years ago with scientists who were melting alloys and semiconductors in space-furnances. Melting and cooling these substances in microgravity is a good way to learn their basic properties, and, perhaps, to create new materials never before seen on Earth. But there was a problem: Semiconductors such as gallium arsenide were eating through the refractory metal containers scientists used (like a cook uses oven pans) to hold materials inside the furnace. The vacuum plasma technique with the FGM process was developed, with support from NASA's Office of Biological and Physical Research, to coat and protect the insides of these containers. Better rocket engines were an unintended but welcome bonus. You never know where basic research will lead!

Street car

Street car engines don't endure the kind of extreme stresses that race car engines do, but they do waste a tremendous amount of energy as heat, which is, in part, why car engines are so inefficient. Coating the piston heads and engine block cylinder heads with NiCrAlY would allow hotter combustion for higher efficiency and longer life, Holmes speculates.
Time will tell what uses engineers find for this new technique, called Functional Gradient Material (FGM), but the technology is already developed. Holmes and his colleagues (Sandy Elam at MSFC, and Tim McKechnie at Plasma Processes, Inc.) have performed more than 100 test firings using small thrust chamber liners made in this way, and they are in the process of scaling up to larger, spaceship-sized designs.

Resilient Rockets

Spacecraft and automobiles could benefit from a new NASA technology that protects the insides of scorching-hot engines.
Once humans return to the Moon and begin "living and working there for increasingly extended periods of time," as outlined in the new Vision for Space Exploration, increasingly frequent trips between the Earth and the Moon will be necessary to ferry people and supplies.
Keeping a "space ferry" parked in Earth orbit, instead of returning it to the ground and spending money and fuel to launch it off the planet's surface each time, is one scenario for making the commute to the Moon more economical. A smaller vehicle would then be used to move people between the ferry and the ground.
google_protectAndRun("render_ads.js::google_render_ad", google_handleError, google_render_ad);
This idea has some advantages, but it also suffers from an engineering obstacle - namely, maintenance. How do you maintain a vehicle that never returns to Earth?
The main engines of the Space Shuttle, the current crème de la crème of liquid rocket propulsion, must be returned to the ground between each mission for extensive maintenance. Severe conditions inside the engine combustion chamber - the reactive chemicals and the temperatures in excess of 2760°C (5,000°F) - cause a roughening of the material from which the combustion chamber liner is constructed (called "blanching"). The inner surface of the liner slowly becomes powdery and flaky, and this corrosion will worsen if the surface isn't polished between each mission.