October 5, 2026 — Southwest Research Institute (SwRI) and The University of Texas at San Antonio (UT San Antonio) are collaborating to better understand how solid propellant burns, with the goal of improving current chemical kinetics models to enhance solid rocket motor (SRM) efficiency and performance. The research could support local resource utilization for future missions to Mars and beyond.
The project, led by SwRI Research Engineer Mariana Chavez Rodriguez and UT San Antonio Associate Professor Dr. Daniel Pineda, is supported by a $125,000 grant from the Connecting through Research Partnerships (Connect) program, which fosters collaboration between the two institutions.
Many missiles and rockets use solid propellants made with ammonium perchlorate, which contains chlorine. While engineers know generally how this fuel burns, the chemical steps involving chlorine species are poorly documented but govern how smoothly and efficiently the fuel burns.
“The chlorine reactions are hard to measure because they happen so quickly, and the chlorine is corrosive, quickly damaging metal parts of test equipment,” Chavez Rodriguez said. “Measuring these reactions during combustion can provide high-quality data to improve chemical kinetics models.”
SwRI and UT San Antonio will use lasers as measuring tools instead of inserting probes or sensors into the burning propellant. As they burn, different chemical species will react to the laser light beam in different ways, telling researchers which chemicals are present and how their concentration changes over time. This process, known as laser absorption spectroscopy (LAS), capitalizes on SwRI’s expertise in solid propellants and UT San Antonio’s laser-based measurement techniques.
“Leveraging our experience and facilities in advanced optical diagnostics and spectroscopy, UT San Antonio will develop a bench-scale, optically accessible reactor that is compatible with the latest quantitative diagnostics, such as mid-infrared high-speed imaging,” Pineda said. “This project could serve as a cornerstone for pursuing longer-term and larger projects related to solid propellants.”
The small-scale test setup at UT San Antonio will allow the researchers to develop and refine laser measurements in a controlled environment. As the work progresses, SwRI will adapt its strand burner to scale up techniques used to measure propellant burn rates under controlled conditions, including LAS.
“Our goal is to better understand the chemical kinetics that show exactly how the fuel burns,” Chavez Rodriguez said. “Integrating these data into existing kinetics models will improve our understanding of how the propellant will perform, helping engineers reliably predict performance, optimize efficiency and design better solid rocket motors for defense and aerospace applications.”
The project could have a long-term impact beyond Earth, as ammonium perchlorate is similar to perchlorates found on Mars. Understanding how perchlorate-based fuels burn could demonstrate how future missions could use Martian resources as a fuel source.
This project was funded (fully or in-part) by The University of Texas at San Antonio, Office of Research and Southwest Research Institute.
For more information, visit Machinery or contact Joanna Quintanilla, +1 210 522 2073, Communications Department, Southwest Research Institute, 6220 Culebra Road, San Antonio, TX 78238-5166.