Design of a Retro Rocket Earth Landing System for the Orion Spacecraft

The Orion spacecraft is tasked with taking humans to space and returning them safely to Earth at a site in the continental United States. To ensure that the crew returns safely to Earth, a landing system must be designed to reduce the terminal velocity so that, upon landing, the impact loads are minimal and the capsule does not roll over. The retro rocket landing system presented here has been currently baselined because of its performance capabilities over other landing attenuation options such as airbags and landing struts. Preliminary fault analysis and mass and volume sizing led to a down-select of various rocket configurations to base mounted vertical rockets that would be exposed when the heatshield separated. Additionally, the design contains horizontal rockets through the backshell that would be exposed by blowout ports. The trades performed for the retro rocket system led to a design consisting of four 7000 lbf vertical rockets sized to reduce the vertical velocity from 25 ft/s to 5 ft/s. Additionally, four 9400-lbf horizontal rockets were sized to reduce horizontal velocities ranging from 0 to 58 ft/s to less than 20 ft/s. This paper summarizes the analysis that led to the selection of this concept as a preliminary design. This design will change as the Orion spacecraft design and landing system requirements are modified.