Atmospheric-Breathing Supersonic Propulsion System for Future Planetary Exploration

Landing humans on Mars will require new Entry, Descent, and Landing (EDL) technologies to advance beyond the current state-of-the-art payload capacity of around one metric ton because human missions will likely require multiple 20 metric ton payload deliveries. Retropropulsive rockets may enable such missions but require significant propellant mass. Atmospheric-Breathing Supersonic Propulsion (ABSP) systems are a novel solution that may reduce entry vehicle total mass by leveraging CO2 in the Mars atmosphere as an oxidizer to combust with on-board solid propellant and generate thrust during the Entry and Descent phases. Eliminating the on-board oxidizer reduces EDL and launch mass requirements along with associated atmospheric breathing vehicle benefits of greater vehicle maneuverability, thrust control, and reusability. Ramjet engines are an ideal candidate for an ABSP system because they contain no moving components and design tools exist that can be adapted to Mars applications. This study focuses on assessing the feasibility of ABSP systems for human Mars exploration and investigating the fuel delivery system for such a ramjet engine. This study develops a parametric solid fuel ramjet engine model, incorporating constraints such as powdered fuel injection rates, to enable optimization and sensitivity studies. Unlike literature studies, input conditions to the model are defined based on unique mission applications: maximizing cross-range, supersonic descent, and precision landing, to focus the study’s scope and evaluate the applicability of ABSP relative to SRP and traditional EDL technologies. The study produces a ramjet engine cycle model validated against heritage data as well as design parameters and performance metrics of ABSP engines tailored to each mission, ultimately informing the most promising applications of the ABSP technology. The experimental PDFB assessment is conducted in conjunction with the propulsion cycle analysis and is informed by literature studies and their follow-on recommendations. A sensitivity study highlights the impact on fuel feed-rates from design parameters such as the fuel/carrier gas mass ratio, powdered metal grain size, and carrier gas pressure, to provide training data for response surface equations. These equations enable rapid performance estimates for use in predicting total fuel system mass and volume and provide supporting evidence for constraints on the ABSP engine model. The experimental effort provides a platform and dataset for use in follow-on studies. The PDFB study increases the existing PDFB testbed’s functionality, determines driving design parameters, and generates regression equations of fuel-delivery performance to be leveraged in engine models.

In order to send humans to Mars, new EDL technologies must be developed. Human missions are predicted to subdivide the total 80t into 20t payloads, delivering them to the Martian surface over several missions. This requires human-class EDL architectures to precisely land supplies to within 1km of each other to minimize the distance needed to gather the assets. An ABSP system is a candidate technology to fulfill such mission requirements due to the mass, maneuverability, and cross-range capabilities of atmospheric breathing vehicles. ABSP is attractive as an alternative to supersonic retropropulsion (SRP) because it also scales well to large payload vehicles and can mitigate the mass penalties of SRP by ingesting the atmosphere of Mars as an oxidizer instead of carrying it on-board. Such ABSP systems can also be reused as an ascent or cruise stage for future transportation on Mars because atmospheric breathing systems are characteristically more maneuverable, reusable, and economic than rocket-based vehicles. Highlighting the relevant applications and research opportunities can drive future maturation efforts, lead to collaboration with universities, and inform future engine testing and fabrication studies. Furthermore, system-integrated testing could motivate infrastructure investments such as new wind tunnel capabilities to support solid metal/CO₂ combustion systems.

This is early/mid-stage (TRL 3) — the most realistic path in is NASA SBIR/STTR, which funds small businesses and research institutions to develop technology aligned with NASA's needs (equity-free, phased funding). Check whether a current SBIR/STTR solicitation topic overlaps with this project's technology area, or contact the project directly (above) to ask.

None of these are guaranteed paths for this specific project — TechPort itself doesn't have an "apply" button. Reaching out to the contact(s) above with a specific question is usually the fastest way to find out what's actually open.