Development of an Earth Smallsat Flight Test to Demonstrate Viability of Mars Aerocapture

Aerocapture has long been considered a compelling orbital maneuver that significantly reduces the cost of a wide variety of Mars orbital missions, as well as potential missions to Venus, Neptune, Titan, and return to Earth. Numerous conceptual studies have advanced the technical maturity of aerocapture to help enable its use on missions to different atmospheric worlds. Despite this technological readiness, the lack of an integrated aerocapture flight system demonstration has often been cited as rationale for not employing the technique on a flight mission. In order to facilitate a potential flight test, recent research has focused on the use of drag modulation-based techniques to greatly reduce the complexity of aerocapture systems. Drag modulation systems utilize changes in a vehicle\u27s drag area during flight to effect control over the vehicle\u27s ballistic coefficient, and therefore its final trajectory. Compared to traditional bank-to-steer lifting methods, these techniques enable use of extremely simple avionics algorithms, sensors and actuators, and eliminate the need for cg offset and an on-board propulsive reaction control system. Due to its simplicity, drag modulation-based aerocapture is a technique that can be readily tested via a smallsat, with results that can be applied to a variety of different planetary missions. This investigation is focused on the development of a conceptual smallsat mission that will demonstrate the feasibility of an aerocapture system. The spacecraft will be deployed as a secondary payload from a GTO; the conditions provided by the high-energy Earth-return trajectory from GTO will help minimize aerocapture targeting and post-maneuver delta-V requirements. Upon entering the atmosphere, the smallsat will employ hypersonic drag-modulation techniques to control the aerocapture maneuver: after enough energy has been lost via atmospheric drag, the spacecraft will jettison a drag shield, thereby modifying its ballistic coefficient and enabling capture into a relevant orbit after the atmospheric pass. Conceptual mission development has been focused on the design of the smallsat and the aerocapture device, as well as the modeling and selection of the spacecraft\u27s atmospheric trajectory. The difference in ballistic coefficients before and after the drag shield is jettisoned will be the primary source of control authority over the aerocapture maneuver; as such, sizing both the main spacecraft body and the drag shield directly drives numerous other mission design aspects. Aerocapture system design is being accomplished through means of a comprehensive trade study, with focus will placed on control requirements, simplicity, and the applicability of the system to other missions. Three-degree-of-freedom numeric simulation can be used to model the spacecraft\u27s trajectory, enabling quick analysis of peak heating and post-aerocapture orbits. Focus has also been placed on the scalability of results to different types of missions at Mars and other targets. This investigation will culminate in a baseline small satellite mission concept that is fully documented, including technical approach, management plan, cost estimation and risk assessment. A successful mission will show that drag modulation-based aerocapture can be used as an effective means of orbit insertion at Earth and other atmospheric worlds, with scalable applications to both large and small spacecraft