Entry Range Capability Analysis of the Orion Crew Module

The Orion crew module utilizes skip entry to significantly increase entry range capability when returning from the moon. This extended range capability allows the vehicle to achieve accurate landings at various land and coastal water landing sites in close proximity to the continental United States throughout the lunar month. Six- degree-of-freedom computer simulation coupled with Monte Carlo and deterministic analysis techniques were used to evaluate the guided range capability of the Orion crew module over a range of navigation, environment, and vehicle uncertainties. Additionally, the effects of hypersonic lift-to-drag ratio and flight-path angle at entry interface on vehicle entry range capability were evaluated. Results indicate that skip entry trajectories provide a significant increase in entry range capability over that of the direct entry and loft trajectories of the Apollo program. Crossrange capability degrades as vehicle lift-to-drag ratio is decreased, but substantial capability remains for vehicle lift-to-drag ratios lower than the Apollo entry vehicle. Accuracy degrades in both downrange and crossrange with steeper entry interface flight-path angles. However, higher lift-to-drag ratios partially mitigate these effects, allowing greater freedom in selection of entry interface flight-path angles. The ability to perform long-range entries and accurate landings over the range of design lift-to-drag ratios currently under consideration may provide significant benefits in operational complexity and cost to the Orion program. However, these benefits must be balanced with increased mass and entry system complexity.