There are two distinct approaches to aerocapture: drag modulation and lift-vector control. All current research under the NASA ROSS In-Space Propulsion Technology Program is based on the drag modulation approach. However, a growing number of researchers are convinced that lift-vector control will be necessary, particularly for the more challenging planetary destinations such as Neptune. Vertigo will research concepts for spacecraft aerocapture using an innovative attached inflatable forebody decelerator that employs lift-vector control. Compared to drag modulation, lift-vector control expands the entry corridor to provide the needed margin for the total of the statistical uncertainties associated with navigation and atmospheric property estimation. Because aerocapture uses aerodynamic forces and not propulsion to decelerate, the amount of fuel required for a mission is greatly reduced. During Phase I Vertigo will define a concept for an attached inflatable forebody decelerator that incorporates lift-vector trajectory control. The results of the Phase I research will form the basis for a Phase II program in which we will perform a detailed evaluation of all aspects of the conceptual aerocapture system to converge on a single design concept for multiple aerocapture missions, and completely analyze the characteristics of spacecraft utilizing the selected aerocapture concepts.
