Advanced engineering design program at the University of Illinois for the 1987-1988 academic year

The participation of the University of Illinois at Urbana-Champaign in the NASA/USRA Universities Advanced Engineering Design Program (Space) is reviewed for the 1987 to 88 academic year. The University's design project was the Manned Marsplane and Delivery System. In the spring of 1988 semester, 107 students were enrolled in the Aeronautical and Astronautical Engineering Departments' undergraduate Aerospace Vehicle Design course. These students were divided into an aircraft section (responsible for the Marsplane design), and a spacecraft section (responsible for the Delivery System Design). The design results are presented in Final Design Reports, copies of which are attached. In addition, five students presented a summary of the design results at the Program's Summer Conference

NASA/USRA University advanced design program

The participation of the University of Illinois at Urbana-Champaign in the NASA/USRA University Advanced Design Program for the 1988 to 1989 academic year is reviewed. The University's design project was the Logistics Resupply and Emergency Crew Return System for Space Station Freedom. Sixty-one students divided into eight groups, participated in the spring 1989 semester. A presentation prepared by three students and a graduate teaching assistant for the program's summer conference summarized the project results. Teamed with the NASA Marshall Space Flight Center (MSFC), the University received support in the form of remote telecon lectures, reference material, and previously acquired applications software. In addition, a graduate teaching assistant was awarded a summer 1989 internship at MSFC

Thermal Risk Mitigation Testing of the DarkNESS Observatory for Fermi NationalAccelerator Laboratory

This paper presents the prototype design and laboratory test results of the thermal control system for the Dark matter as sterile Neutrino Search Satellite (DarkNESS). A collaboration between Fermilab, CU Aerospace, and the University of Illinois Department of Aerospace Engineering’s Laboratory for Advanced Space Systems (LASSI), the 6U satellite uses a Skipper CCD to detect weak 3.55 – 3.57 keV X-ray emissions, previously discovered by the XMM-Newton and Chandra X-ray observatories. To minimize read-out noise, the thermal control system incorporates a 10 W integral rotary cryocooler and passive heat transfer elements, maintaining the CCD at an operating temperature of 170 K. Analyses of the Earth\u27s obstruction of the instrument’s field of view and the impact of external heating on the instrument aperture established performance requirements and attitude constraints for the thermal control system. A high-fidelity test of a preliminary design was performed in a thermal vacuum chamber, prompting modifications to improve the thermal system design margins. This effort precedes the Critical Design Review milestone

Plume study of an electrospray thruster using a HAN-based dual-mode ionic liquid propellant

This paper investigates the electrospray performance of FAM-110A, a novel hydroxylammonium nitrate (HAN) based ionic liquid propellant developed for a chemical-electric dual-mode space propulsion system. FAM-110A was tested using a PET-100 electrospray thruster with a porous emitter, and its electrospray performance was compared with the widely used 1-Ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) propellant. The FAM-110A thrusters demonstrated a lower onset voltage and comparably high emission current. An external electric field was applied in front of the plume collecting plate to study the current measurement accuracy and the effect of secondary species emissions from high-energy particles collidingon the surface. The spatial distribution of the thruster plume current was profiled using a 2-axis rotary stage. Both FAM-110A and EMI-BF4 showed asymmetrical plume profiles, with FAM-110A having a smaller overall plume angle. The energy distribution of the plume particles was measured using a retarding potential analyzer, and the results showed that the FAM-110A had a highly mono-energetic plume with little evidence of fragmentation in the field-free region. Light emission in electrospray thruster operation was observed using long-exposure photography. This plume characterization study suggests that FAM-110A can be run in porous electrospray thrusters with promising performance, and further development of this technology is recommended

Emission characterization of porous electrospray thrusters with actively controlled flow rate

A pressurized propellant feeding system was designed and tested for a porous-emitter electrospray thruster. The system provides a preliminary design for an electrospray-monopropellant dual-mode propulsion system that uses a HAN-based ionic liquid propellant. For ease of initial experimental validation, a conventional ionic liquid propellant, EMI-BF4, was used in this pressurize-feeding electrospray system. The dry thruster was fed from a pressurized propellant storage beaker via a tubing. The dimensions of the feeding tube were calculated to deliver the nominal flow rate. In order to reduce the time of filling the thruster, a bypass feeding line with a high flow rate was integrated into the system. The transient behavior of the fluidic impedance and flow rate during the initial propellant filling stage were computed for analysis. The flow rates and propellant feeding performance using both the nominal and bypass feeding lines were tested and proved effective. The current-voltage characteristics of the electrospray thruster were measured in vacuum tests, with the propellant delivery pressure changed from 1 bar to 0 bar. The current values at the negative polarity significantly increased with higher feeding pressure, whilst the positive currents only experienced minor variations. With the pressure changing from 1 bar to 0 bar, the current at -3000 V changed from -807.54 μA to -217.18 μA,whilst in comparison, the current at +3000 V only varied from +216.52 μA to +300.29 μA. This preliminary design and test demonstrated that using a pressurized propellant feeding system on an electrospray thruster with a porous emitter is feasible. This opens up the possibility that the electrospray emission performance can be controlled not only by the thruster voltage but also by the propellant delivery pressure

Mission performance assessment of multimode propulsion for satellite servicing applications

We assess the mission performance of a multimode (monopropellant-electrospray dual-mode) propulsion system relative to current state-of-the-art chemical, electric, and hybrid chemical-electric propulsion systems for satellite servicing applications. Performance is assessed for both low-Earth orbit servicers (with total mass of approximately 100 kg) and geosynchronous orbit servicers (with total mass of approximately 1000kg). First-order spacecraft sizing routines are developed to determine spacecraft properties for each propulsion system option based on historical data, propulsion system properties,and physical and geometric constraints. The overall servicing missions are decomposed into a set of discrete maneuvers for both servicer concepts. Simulations are developed for each maneuver and propulsion system to determine flight performance,including∆V and time of flight.Finally, metrics of comparison between the different propulsion system options are proposed to illustrate the strengths and weaknesses of each propulsion system option over the candidate mission scenarios. Mission scenarios are composed of admissible sequences of modeled maneuvers. Comparison metrics are then used to highlight the costs and benefits of the assessed propulsion system options relative to each other. Results indicate that the hybrid and multimode systems provide significant mission flexibility for satellite servicing applications, but the multimode does so with a significantly lower structural ratio

Green ionic liquid multimode monopropellant based chemical microthruster

A chemical microthruster was designed and tested that catalytically decomposes green ionic liquid propellant specifically designed for multimode space propulsion. The monopropellant is called FAM-110A and is synthesized by mixing [Emim][EtSO4] and HAN in the ratio of 59%-41% by weight. The microthruster is designed to produce 0.1 N thrust and fabricated from stainless steel using additive manufacturing. The catalyst is 0.3-mm-diameter Platinum-coated γ alumina. The manufactured thrusters have exit and throat areas that are up to 50% different from the design specifications due to the material type, size, and manufacturing process. The decomposition is achieved by electrically heating the thruster. Several hot fire tests were conducted and for the first time the multimode propellant FAM-110A was demonstrated in traditional catalytic decomposition thrusters. The tests were conducted for catalyst bed temperatures of 120°C and 500°C, and propellant flow rates of 40μL/s and 65μL/s. The highest temperature measured by thermocouples within the thruster interior was 650°C

Characterization of ionic liquid multimode propellant operating in a porous glass electrospray thruster

Multimode space propulsion is an emerging technology that shows a promising increase in mission flexibility, adaptability, and mass savings for specific missions [1]. Finding a propellant that operates well in multiple propulsive modes is a key step in getting multimode propulsion systems flying in space. This study characterizes a novel multimode propellant named FAM-110A through operation in a porous glass electrospray thruster. Measurements acquired include current-voltage characteristic curves, plume energy via a retarding potential analyzer, and mass to charge ratio via a linear time of flight spectrometer. It is demonstrated that FAM-110A operates stably in cation emission, anion emission, and bipolar operational modes.The propellant has a higher onset voltage and emits less current than EMIM BF4 operating in the same thruster. The electrospray plume emitted during operation with FAM-110A appears to be monoenergetic and the time of flight data indicates that the EMIM monomer species is most likely the dominant species being emitted during cation emission operation