Description: To return a sample from the surface of Mars or any of the larger moons in the solar system will require a propulsion system with a comparatively large delta-V capability. Consequently, significant propellant mass will be required. While it is technically feasible to generate O2 and CO propellants by electrolysis of CO2 from the Martian atmosphere, it will only work on bodies where there is significant CO2 in the atmosphere, and the mass of the required infrastructure (electrolyzer, batteries, solar panels) is substantial. A recent study showed that a hybrid rocket with multi-start capability trades more favorably than either a CO2 electrolysis system or a bipropellant system where the propellants are generated on Earth. Using a high-performance hybrid propellant combination and being able to restart the hybrid rocket are the keys. In previous and ongoing work, Ultramet has demonstrated that electrically heated open-cell silicon carbide foam can be used as an igniter for both monopropellant and bipropellant rocket engines. Due to its low mass, excellent oxidation resistance, and favorable electrical characteristics, the foam can be heated to 1300°C in just seconds, which enables it to quickly ignite any propellant flowing through it. The Phase I project demonstrated that a foam heater could be turned on and off any number of times and that it was capable of heating oxygen and igniting paraffin. Applied to a portion of the oxidizer stream in a hybrid rocket engine, this will provide multi-start capability. In Phase II, Ultramet will team with Parabilis Space Technologies to design, fabricate, and test a hybrid rocket ignition system suitable for use with O2, NTO, or MON-25 on a Mars ascent vehicle.

Benefits: This technology will initially be targeted at hybrid rockets, and the near-term application will be hybrid rockets for a Mars sample return mission. More generally, foam-based heaters that are amenable to use at high temperatures in highly oxidizing environments can be used as igniters for virtually any non-hypergolic propellant combination. These include O2/CO, LOX/CH4, LOX/ethanol, and LOX/RP-1 among others. They can also be used to ignite hydrazine, as well as ionic liquid monopropellants such as LMP-103S and the E, Q, and A blends of AF-M315. This makes the technology applicable to engines of virtually any thrust class, from large booster engines to small attitude control engines. Specific missions of interest to NASA include ascent/descent engines for missions to Mars, the Moon, other planetary moons, and asteroids.

This technology can be used for igniting non-hypergolic bipropellants, ionic liquid monopropellants, and hydrazine in main and attitude control engines on commercial and military spacecraft, as well as main and reaction control engines on commercial and military boosters. Other aerospace applications include ignition systems and catalyst preheaters for aeropropulsion turbine engines and air heaters for hypersonic wind tunnels similar to the Aerodynamic and Propulsion Test Unit at Arnold Engineering Development Center (AEDC). Non-aerospace applications include ignition systems and catalyst heaters for turbine engines used for terrestrial power generation, and gas and water heaters where high efficiency is critical.