About

Matthew Gilpin is a Senior Lecturer in the Aerospace and Mechanical Engineering Department at the University of Southern California. He is affiliated with the In-Space Propulsion Research (InSPR) Laboratory. His role involves teaching and research related to aerospace engineering, with a focus on in-space propulsion technologies. Gilpin's work supports the laboratory's mission to advance propulsion systems for space exploration and satellite applications. As part of his academic responsibilities, he mentors students at various levels, including M.S. and undergraduate students, contributing to the development of future aerospace engineers. His expertise and contributions are integral to the ongoing research and educational efforts within the InSPR Laboratory and the broader aerospace community at USC.

Research topics

• Computer Science
• Engineering
• Physics
• Aerospace engineering
• Mechanics
• Materials science
• Operating system
• Human–computer interaction
• Mechanical engineering
• Environmental science

Selected publications

• Design and Experimental Validation of a Gallium Field Emission Electric Propulsion Thruster

  2025-01-01

  articleSenior author

  Field Emission Electric Propulsion (FEEP) thrusters use a liquid metal ion source (LMIS) to generate thrust. They are desirable due to their compact and simple architecture and instantaneous sub-μN-scale throttling capabilities. Gallium is advantageous over many common propellants such as indium and cesium due to its combination of low melting temperature (85.6 °F), limited reactivity, and low toxicity. Presented is the design, manufacturing, and validation of a low-cost, gallium-fueled, slit-type FEEP thruster. Measurements of plume current distribution, plume energy spectra, thruster mass flow, and emitter/extractor voltage and current were conducted alongside visible spectrum imaging. This allowed for accurate characterization of the thrust, specific impulse, and thrust efficiency of the Gallium FEEP Thruster (GFT). This study indicates that compact FEEP architectures can be fabricated using 3-axis machining and can be used effectively with gallium as a propellant, leading to lower operation temperatures than indium FEEP thrusters and higher system safety than cesium FEEP thrusters. The thruster was experimentally measured to produce 100 ± 40 μN of thrust, with a specific impulse of 10,000 ± 4,000 seconds and a power draw, including heating, of 14 ± 2 W.

  PublisherDOI

• Ultrasonic Actuation Technology for Particulate Mitigation on Martian Solar Panels

  2025-01-01

  articleSenior author

  The rapid developments in interplanetary exploration underscore the need for more efficient, self-sustaining energy production while exposing major limitations in current autonomous decontamination technologies. With the recent focus on Martian exploration, there have been six rovers sent to the Red Planet; four of which used solar as a primary energy source, and none of which included reliable decontamination technology. Studies have shown that Martian regolith accumulation on solar panels results in an average power loss of 0.2% per sol, with some missions experiencing even higher rates depending on local conditions [1]. In order to combat these losses and improve the effectiveness of future Mars exploration missions and habitation, this study explores Near-Field Acoustic Levitation (NFAL) as a non-contact dust removal method for solar energy. Experimental tests assessed the effectiveness of placing tempered glass above a solar panel and optimized ultrasonic transducer positioning for efficient dust removal. Using a solar simulator, the glass demonstrated an improved solar power output of up to 9.3 ± 0.1%. Optimization with dust simulants identified an emitter-receiver configuration—emitter at the glass’s bottom—as the most effective, achieving a 95 ± 4% dust mass reduction after 20 seconds of actuation and with an angle of 20° with respect to the ground. Video analysis of the actuation supported these values with a steady state dust coverage reduced to 6 ± 3% of initial coverage. Testing with various dust types to confirm experimental validity showed comparable results. Specifically, MGS-1 particles achieved 94 ± 3% mass removal in terrestrial atmospheric conditions following 120 seconds of actuation. Furthermore, initial tests in low-pressure environments (<0.4 torr ambient pressure) demonstrated effective dust removal. Additional tests will characterize the response at angles below 20º using charged MGS-1 particles. Ultrasonic solar cleaning provides an effective solution to dust accumulation in extraterrestrial applications, an absolute necessity as humans attempt to extend their reach into the cosmos. [1] Lorenz, R. D., Martínez, G. M., Spiga, A., Vicente-Retortillo, A., Newman, C. E., Murdoch, N., Forget, F., Millour, E., and Pierron, T., “Lander and rover histories of dust accumulation on and removal from solar arrays on Mars,” Planetary and Space Science, vol. 207, Nov. 2021, p. 105337. https://doi.org/10.1016/j.pss.2021.105337

  PublisherDOI

• Hands-On Measurement and Instrumentation Course Accessibility for Visually Impaired Students

  2024

  • Computer Science
  • Computer Science
  • Human–computer interaction

  Abstract The Aerospace and Mechanical Engineering Department at USC has adapted our hands-on "Mechoptronics" laboratory course for visually impaired students. This was accomplished through the creation of new accessibility tools and by adapting core parts of the laboratory experience away from non-accessible software such as LabView in favor of accessible software such as MATLAB. The objective of this project was to maintain the laboratory experience and allow for active learning and the moments of discovery in the laboratory which are essential to practical education. The first half of USC's Mechoptronics course is teaching measurement and instrumentation and this was facilitated through the in-house creation of a "Tactile Oscilloscope." This accessibility device used the Orbit Grafiti tactile display as an output for a standard laboratory oscilloscope. These two devices were bridged with custom MATLAB software allowing for the student use of controls and inputs on the standard oscilloscope while using the tactile display for signal output and auditory output for oscilloscope settings and measurements. The second half of Mechoptronics is focused on automation and control. This half of the course was adapted to use MATLAB scripting enabling the use of standard National Instruments hardware without relying on LabView's visual programming language. The accessible curriculum recently developed at USC can serve as a roadmap for other schools working to adapt hands-on laboratory courses for the visually impaired. Furthermore, the development of our accessible curriculum has highlighted accessibility gaps present in commercial measurement and automation tools which will require additional customization and collaboration with commercial entities in the future.

  PublisherOA PDFDOI

• XFOIL Performance Validation for Medium- Scale Variable Pitch UAV Rotor Systems

  R&D Journal · 2023-08-01

  articleOpen accessSenior author

  This study focuses on experimentally validating the performance of XFOIL, a sophisticated software airfoil analysis tool used for approximating lift and drag coefficients. XFOIL output data was incorporated into a theoretical model simulating a variable pitch rotor system operating in a hovering state. The output of the Blade Element Momentum Theory (BEMT) rotor model is compared to thrust and power output performance data collected from a constructed rotor test bench and analysed in MATLAB. Using XFOIL as input, the BEMT rotor model was observed to yield good robust results when compared to experimental data, but demonstrated sensitivity to airfoil performance characteristics, laying the groundwork for future empirical validation. In comparing BEMT model performance, it was interesting to find that thrust performance remained within tolerance in contrast to an overprediction of rotor power output resulting from XFOIL drag at high blade pitch angles. Upon further interrogation by means of variable isolation, XFOIL demonstrated instability resulting from sensitivity to variability of model constraints. Modification of rotor geometry definitions or environmental constants beyond the test environment framework showed simulated systems may not necessarily behave reliably nor enhance output performance. This highlights the critical importance and utility of experimentation for understanding theoretical model behaviour or validating simulation output performance.

  PublisherOA PDFDOI

• Womersley's solution for the measurement of volume flow rates in transient laminar flow tubes

  Physics of Fluids · 2022 · 2 citations

  1st authorCorresponding
  • Computer Science
  • Mechanics
  • Physics

  The characterization of transient flows within the Reynolds number range of Re = 10–100 and the Womersley number range α = 0.8–10 is required for the ongoing development of green monopropellant thrusters. However, at the ml/min scale flow rates of interest, these measurements are outside the capabilities of current commercial flow meters. It is proposed here that transient flows under the required dynamic conditions can be characterized via Womersley's solution for transient flow in a rigid tube. This solution method requires only the measured transient pressure gradient within a controlled laminar flow section and can be accomplished using existing commercial pressure measurement hardware. Experiments were performed where flow similarity was maintained with the ultimate thruster characterization application, but the radius of the flow passage was increased so that flows could be simultaneously characterized by both the proposed solution method and a commercial ultrasonic flow meter. It was shown that across the range of interest, applying Womersley's solution to a measured pressure gradient was an effective method of transient flow characterization. Additionally, it was shown that non-periodic flows can be characterized except for the initial flow startup transient with solution convergence times approximating the analytical solution to starting flow in a pipe. While these results were expected due to an experimental design matching the assumptions required for Womersley's analytic solution, this work demonstrates that this method is practically feasible as novel instrumentation enabling previously unobtainable measurements.

  PublisherDOI

• Dual-axis thrust stand for the direct characterization of electrospray performance

  Review of Scientific Instruments · 2022 · 18 citations

  1st authorCorresponding
  • Aerospace engineering
  • Environmental science
  • Mechanical engineering

  A dual-axis torsional thrust stand was successfully demonstrated at the Air Force Research Laboratory, enabling direct simultaneous thrust and mass loss measurement for the Air Force Electrospray Thruster Series 2 passively fed electrospray thruster. The dual-axis system is effectively two nulled torsional thrust stands sharing a single dual-axis gimbal with a thrust and mass resolution of ±0.2 µN and ±0.04 mg, respectively. The development of this system was inspired by a need for direct efficiency characterization of electrosprays via in situ mass measurements, and performance was compared to thruster masses measured pre- and post-testing using an analytical balance. Mass consumption data captured via the dual-axis stand, which is calibrated to a traceable uncertainty of 1.6%, varied between -5% and 18% as compared to analytical balance measurements throughout a multi-month testing effort highlighting the limitations in pre/post-weighing as a method for capturing propellant consumption due to absorption of atmospheric moisture when thrusters are removed from vacuum. Thrust stand tests were limited to short term operation with a daily available testing window of ∼5 h due to thrust stand drift following the 24 h cyclic temperature variations of the testing facility. A thorough investigation into the root cause of ambient thermal drift suggests that the thermal response of commercial flex-pivot bearings is directly producing spurious torques on the order of 10 μN m/°C. Additionally, unresolved charging effects on thrust stand hardware currently limit thrust stand operation to tests operating with a positive thruster polarity. Further development and long duration test stability require both a targeted investigation into flex-pivot thermal response and minimization of facility effects.

  PublisherDOI

• List of contributors

  Elsevier eBooks · 2020-09-04

  book-chapter
  PublisherDOI

• Ultra-high temperature space power applications

  Elsevier eBooks · 2020-09-04 · 1 citations

  book-chapter1st authorCorresponding
  PublisherDOI

• High Energy Advanced Thermal Storage (HEATS)

  2018-11-30 · 3 citations

  article1st authorCorresponding
  Publisher

• High temperature latent heat thermal energy storage to augment solar thermal propulsion for microsatellites

  2015-07-20 · 14 citations

  articleOpen access1st authorCorresponding

  Solar thermal propulsion (STP) offers an unique combination of thrust and efficiency, providing greater total ?V capability than chemical propulsion systems without the order of magnitude increase in total mission duration associated with electric propulsion. Despite an over 50 year development history, no STP spacecraft has flown to?date as both perceived and actual complexity have overshadowed the potential performance benefit in relation to conventional technologies. The trend in solar thermal research over the past two decades has been towards simplification and miniaturization to overcome this complexity barrier in an effort finally mount an in?flight test. ? A review of micro?propulsion technologies recently conducted by the Air Force Research Laboratory (AFRL) has identified solar thermal propulsion as a promising configuration for microsatellite missions requiring a substantial ?V and recommended further study. A STP system provides performance which cannot be matched by conventional propulsion technologies in the context of the proposed microsatellite ?inspector" requiring rapid delivery of greater than 1500 m/s ?V. With this mission profile as the target, the development of an effective STP architecture goes beyond incremental improvements and enables a new class of microsatellite missions. ? Here, it is proposed that a bi?modal solar thermal propulsion system on a microsatellite platform can provide a greater than 50% increase in ?V vs. chemical systems while maintaining delivery times measured in days. The realization of a microsatellite scale bi?modal STP system requires the integration of multiple new technologies, and with the exception of high performance thermal energy storage, the long history of STP development has provided ?ready" solutions. ? For the target bi?modal STP microsatellite, sensible heat thermal energy storage is insufficient and the development of high temperature latent heat thermal energy storage is an enabling technology for the platform. The use of silicon and boron as high temperature latent heat thermal energy storage materials has been in the background of solar thermal research for decades without a substantial investigation. This is despite a broad agreement in the literature about the performance benefits obtainable from a latent heat mechanisms which provides a high energy storage density and quasi?isothermal heat release at high temperature. ? In this work, an experimental approach was taken to uncover the practical concerns associated specifically with applying silicon as an energy storage material. A new solar furnace was built and characterized enabling the creation of molten silicon in the laboratory. These tests have demonstrated the basic feasibility of a molten silicon based thermal energy storage system and have highlighted asymmetric heat transfer as well as silicon expansion damage to be the primary engineering concerns for the technology. For cylindrical geometries, it has been shown that reduced fill factors can prevent damage to graphite walled silicon containers at the expense of decreased energy storage density. ? Concurrent with experimental testing, a cooling model was written using the ?enthalpy method" to calculate the phase change process and predict test section performance. Despite a simplistic phase change model, and experimentally demonstrated complexities of the freezing process, results coincided with experimental data. It is thus possible to capture essential system behaviors of a latent heat thermal energy storage system even with low fidelity freezing kinetics modeling allowing the use of standard tools to obtain reasonable results. ? Finally, a technological road map is provided listing extant technological concerns and potential solutions. Improvements in container design and an increased understanding of convective coupling efficiency will ultimately enable both high temperature latent heat thermal energy storage and a new class of high performance bi-modal solar thermal spacecraft.

  PublisherOA PDFDOI

Frequent coauthors

• Marcus Young

  12 shared

• David Scharfe

  11 shared

• Emma Singer

  University of Southern California

  9 shared

• Matthew Giles

  Southern California University for Professional Studies

  9 shared

• Joy Uehara

  Southern California University for Professional Studies

  9 shared

• Jessica Aftosmis

  University of Southern California

  9 shared

• Haylee Mota

  Southern California University for Professional Studies

  6 shared

• Rebecca N. Webb

  5 shared

Labs

• In-Space Propulsion Research (InSPR) LaboratoryPI

Education

• Ph.D., Aerospace Engineering

  University of Southern California

  2000

• M.S., Aerospace Engineering

  University of Southern California

  1996

• B.S., Aerospace Engineering

  University of Southern California

  1994