Characterization of ionic liquid monopropellants for a multi-mode propulsion system

Multi-mode micropropulsion is a potential game-changing technology enabling rapidly composable small satellites with unprecedented mission flexibility. Maximum mission flexibility requires one shared propellant between the chemical and electric systems. A deep eutectic 1:2 molar ratio mixture of choline-nitrate and glycerol ([Cho][NO3] - glycerol) is investigated as a fuel component in a binary mixture propellant for such a multi-mode micropropulsion. Specifically, binary mixtures of the novel ionic liquid fuel with hydroxyl-ammonium nitrate (HAN) and ammonium nitrate (AN) are considered and compared against the previously investigated propellant [Emim][EtSO4]-HAN. Chemical rocket performance simulations predict this new propellant to have higher performance at lower combustion temperature, relaxing catalyst melting temperature requirements and making it a promising alternative. A qualitative investigation of synthesized propellants on a hot plate in atmosphere indicates the AN mixtures are significantly less reactive, and are therefore not investigated further. Quantitative reactivity studies using a microreactor indicate both 65:35% and 80:20% by mass [Cho][NO3] - glycerol to HAN propellants have a decomposition temperature 26-88% higher than [Emim][EtSO4]-HAN, depending on the catalyst material. The results indicate [Emim][EtSO4]-HAN with platinum catalyst is still most promising as a multi-mode micropropulsion propellant. Also, the linear burn rate of this monopropellant is determined to aid design of the microtube catalytic chemical thruster. With the design pressure of 1.5 MPa the linear burn rate of this propellant used for designing the multi-mode propulsion system is 26.4 mm/s. Based on this result, the minimum flow rate required is 0.31 mg/s for a 0.1 mm inner diameter feed tube and 3180 mg/s for a 10 mm inner diameter feed tube --Abstract, page iv

Characterization of a Novel Ionic Liquid Monopropellant for Multi-Mode Propulsion

A deep eutectic 1:2 molar ratio mixture of choline-nitrate and glycerol [Cho][NO3] - glycerol is investigated as a fuel component in a binary mixture propellant for multi-mode micropropulsion. Specifically, binary mixtures of the novel ionic liquid fuel with hydroxyl-ammonium nitrate (HAN) and ammonium nitrate (AN) are considered and compared against our previously investigated propellant [Emim][EtSO4]-HAN. Chemical rocket performance simulations predict this new propellant to have higher performance (280 vs. 250 sec specific impulse) at lower combustion temperature (1300 vs. 1900K), relaxing catalyst melting temperature requirements and making it a promising alternative. Qualitative experimental investigation of synthesized propellants on a hot plate in atmosphere indicate the AN mixtures are significantly less reactive, and are therefore not investigated further. Quantitative reactivity studies using a microreactor indicate that both 65:35% and 80:20% by mass [Cho][NO3] - glycerol to HAN propellants have a decomposition temperature 26-88% higher than [Emim][EtSO4]-HAN, depending on the catalyst material. Additionally, the decomposition rate (or self-heating rate) was 2 to 17 times slower for [Cho][NO3] - glycerol - HAN on titanium and platinum catalysts, but the 65:35% propellant decomposition rate was approximately 10 °C/s (37%) faster on rhenium. It was also observed that propellants with the novel ionic liquid fuel contain endothermic reaction steps, and therefore higher input heat flux was required to maintain a temperature rise. Overall the results indicate [Emim][EtSO4]-HAN with platinum catalyst is still most promising as a multi-mode micropropulsion propellant

Development and Flight of a Stereoscopic Imager for Use in Spacecraft Close Proximity Operations

Proximity operations about noncooperative resident space objects (RSOs) is a current area of research with the intent to enable many useful on-orbit missions. One method of performing passive proximity operations about a noncooperative RSO uses two cameras to obtain stereo line-of-sight data to the RSO in order to fully resolve the relative position and velocity of the RSO and navigate about it. An overview of the MR and MRS SAT mission, in which a stereoscopic imager is used aboard MR SAT to navigate about MRS SAT (a mock noncooperative RSO) is presented. The developed hardware and algorithms used by the stereoscopic imaging sensor, as well as the guidance, navigation, and control subsystems, are presented. A software-in-the-loop simulation is presented to demonstrate the expected on-orbit performance of the MR and MRS SAT mission