|PROPOSAL NUMBER:||06 S1.01-9456|
|SUBTOPIC TITLE:||Surface Robotic Exploration|
|PROPOSAL TITLE:||Advanced Gashopper Mobility Technology|
SMALL BUSINESS CONCERN
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PRINCIPAL INVESTIGATOR/PROJECT MANAGER
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TECHNICAL ABSTRACT ( Limit 2000 characters, approximately 200 words)
The Mars Gas Hopper, or "gashopper" is a novel concept for propulsion of a robust Mars flight and surface exploration vehicle that utilizes indigenous CO2 propellant to enable greatly enhanced mobility. The gashopper will first retrieve CO2 gas from the Martian environment to store it in liquid form at a pressure of about 10 bar. When enough CO2 is stored to make a substantial flight to another Mars site, a thermal storage bed is heated to ~1000 K and the CO2 propellant is warmed to ~300 K to pressurize the tank to ~65 bar. A valve is then opened, allowing the liquid CO2 to pass through the hot thermal storage bed that heats and gasifies the CO2 for propulsion. Gashopper can be designed to function as either ballistic flight vehicles or winged airplanes, with the former offering simplicity and the latter greater range. The advantage of the gashopper is that it provides Mars exploration with a fully controllable aerial reconnaissance vehicle that can repeatedly land and explore surface sites as well.
The key technical issue that determines the potential performance of a gashopper is the overall specific heat of the thermal storage bed. In previous work, Pioneer Astronautics has demonstrated working gashopper airplanes and ballistic flight vehicles that utilized magnesium oxide pellets for thermal storage. While convenient for test purposes, MgO has a specific heat that is only roughly equal to CO2. This severely limits the attainable mass ratio and thus vehicle range. In contrast, lithium has four times the specific heat of CO2, so its use as a gashopper thermal bed material would greatly improve vehicle performance. The low density and liquid nature of high temperature lithium makes its utilization for gashopper engines a challenge. In the proposed program, Pioneer will resolve this challenge by designing, building, and testing high specific heat gashopper engines using liquid lithium for thermal storage.
POTENTIAL NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
The gashopper concept is primarily designed to enable greatly enhanced mobility for robotic Mars exploration vehicles. However the advanced gashopper engine system (AGE) has many potential important commercial applications in space. Small AGE thrusters could be used for stationkeeping and reaction control system (RCS) propulsion for satellites. Currently the propellant of choice for such applications is monopropellant hydrazine, which is extremely toxic, dangerous, expensive, and offers a rather low performance (Isp = 220 s). Small AGE based propulsion systems with ammonia propellant will be much cheaper, safer, and easier to integrate than hydrazine, while offering comparable or even superior specific impulse performance. If the AGE operates above 1200 K, there can also be an extension of satellite life. With their ability to store thermal energy over time and release it suddenly, advanced gashopper engines offer all the flexibility, reliability and safety of resistojets with much higher thrust. Thus, gashopper engine technology could find a major commercial market in the satellite industry. Advanced gashopper engines could also be used to great advantage to provide stationkeeping propulsion for the International Space Station employing waste CO2 from the life support system as propellant and the AGE to provide thrust at a much higher level than would be possible using resistojets.
POTENTIAL NON-NASA COMMERCIAL APPLICATIONS ( Limit 1500 characters, approximately 150 words)
Another possible commercial application for advanced gashopper engine (AGE) technology is for rocket assisted takeoff (RATO) units for small aircraft. The AGE can easily be made to deliver large amounts of thrust, and because it can use water as propellant it poses no danger of fire to the surrounding area. Therefore an AGE RATO system offers interesting practical possibilities, which in fact were demonstrated by the short takeoffs achieved by the aircraft flown in the LaRC Phase 1 gashopper airplane program. One concept would be to build droppable integrated tank/engine units that would be heated on the airfield using locally available electric power. It sometimes happens that under emergency conditions an airplane might be forced to land at an airfield that is to short for it to takeoff from. Using a detachable RATO unit to augment thrust, the airplane could be made airborne again. Propellant could be obtained from local water sources, and autogenously pressurized by heating. Since the use of a RATO engine in such a case would avoid loss of an entire aircraft, the sale of such a RATO assist could be priced high enough to justify using such a system, even if it had to be expended after being dropped from a single flight. A suitable parachute system attached to the RATO unit might make expending such systems unnecessary.
AGE systems could also be used to store solar thermal power acquired during the day and then generate electricity at very high efficiency at night.
|NASA's technology taxonomy has been developed by the SBIR-STTR program to disseminate awareness of proposed and awarded R/R&D in the agency. It is a listing of over 100 technologies, sorted into broad categories, of interest to NASA.|
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