NASA SBIR 2004 Solicitation


PROPOSAL NUMBER: 04 X6.07-9550
SUBTOPIC TITLE: In-Space Propulsion (Nuclear)
PROPOSAL TITLE: Alternate Propellant Thermal Rocket

SMALL BUSINESS CONCERN (Name, E-mail, Mail Address, City/State/Zip, Phone)
Pioneer Astronautics
11111 W. 8th Ave., Unit A
Lakewood, CO 80215-5516

PRINCIPAL INVESTIGATOR/PROJECT MANAGER (Name, E-mail, Mail Address, City/State/Zip, Phone)
Robert Zubrin
11111 W. 8th Ave., Unit A
Lakewood, CO 80215-5516

The Alternate Propellant Thermal Rocket (APTR) is a novel concept for propulsion of space exploration or orbit transfer vehicles. APTR propulsion is provided by utilizing a nuclear thermal reactor or solar thermal engine to heat a space storable propellant, preferably consisting of a volatile indigenous to the destination world, to form a high thrust rocket exhaust. Candidate propellants whose performance, materials compatibility, and ease of acquisition make them worthy of examination for APTR propulsion of exploration vehicles include carbon dioxide, water, methane, and methanol. An APTR utilizing indigenous CO2 propellant potentially offers high payoff to a robotic or manned Mars mission, both by sharply reducing the initial mission mass required in low Earth orbit, and by providing Mars exploration with unlimited mobility and global access. Additionally, an APTR could give nearly unlimited mobility to asteroid or outer solar system probes, while one using methane or nitrogen propellant could enable a Titan sample return mission. The APTR can also be used as the propulsion system for a high performance space storable orbit transfer system moving payloads from LEO to GEO or other orbits of commercial interest. In this case, leading candidate propellants include methane, ammonia, and methanol.

APTRs have important commercial applications for satellites. A reusable orbit transfer vehicle using a space storable APTR system with comparable performance to the 450 s available from the cryogenic H2/O2 Centaur would represent a major cost saving to commercial satellite delivery. Small APTR engines powered by electrical heaters could be used for stationkeeping and RCS propulsion for satellites. APTR propellants are much cheaper, safer, and easier to integrate than toxic hydrazine, and could offer twice hydrazine's specific impulse. For a given RCS propellant allocation, this could double a satellite's useful life, resulting in a major saving to the satellite industry.

The commercial potential of APTR technology goes way beyond the APTR thruster market itself. The use of water or CO2 as propellant in a high temperature thermal rocket requires the development of high temperature oxidation-resistant coatings. The development of such ultra-high temperature protective coatings for APTRs would also create a technology that could play a vital role in the development of numerous types of high performance chemical rockets, and more than that, find abundant use in a wide range of high-temperature oxidizing-environment industrial applications on Earth as well. The markets for commercial applications of such material technology are vast.