Real-time 3-D flight guidance with terrain for the X-38

The NASA Johnson Space Center is developing a series of prototype flight test vehicles leading to a functional Crew Return Vehicle (CRV). The development of these prototype vehicles, designated as the X-38 program, will demonstrate which technologies are needed to build an inexpensive, safe, and reliable spacecraft that can rapidly return astronauts from onboard the International Space Station (ISS) to earth. These vehicles are being built using an incremental approach acid where appropriate, are taking advantage of advanced technologies that may help improve safety, decrease development costs, reduce development time, as well as outperform traditional technologies. This paper discusses the creation of real-time 3-D displays for flight guidance and situation awareness for the X-38 program. These displays feature the incorporation of real-time GPS position data, three-dimensional terrain models, heads-up display (HUD), and landing zone designations. The X-38 crew return vehicle is unique in several ways including that it does not afford the pilot a forward view through a wind screen, and utilizes a parafoil in the final flight phase. As a result, on-board displays to enhance situation awareness face challenges. While real-time flight visualization systems limited to running on high-end workstations have been created, only flight-rated Windows are available as platforms for the X-38 3-D displays. The system has been developed to meet this constraint, as well as those of cost, ease-of-use, reliability and extensibility. Because the X-38 is unpowered, and might be required to enter its landing phase from anywhere on orbit, the display must show, in real-time, acid in 3 dimensions, the terrain, ideal and actual glide path, recommended landing areas, as well as typical heads-up information. Maps, such as aeronautical charts, and satellite imagery are optionally overlaid on the 3-D terrain model to provide additional situation awareness. We will present a component-based toolkit for building these displays for use with the Windows operating systems.