Coming Home: Reentry and Recovery From Space

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This study represents a means of highlighting the myriad of technological developments that made possible the safe reentry and return from space and the landing on Earth. This story extends back at least to the work of Walter Hohmann and Eugen Sänger in Germany in the 1920s and involved numerous aerospace engineers at the National Advisory Committee for Aeronautics /NASA Langley and the Lewis and Ames Research Centers. For example, researchers such as H. Julian Allen and Alfred J. Eggers, Jr., at Ames pioneered blunt-body reentry techniques and ablative thermal protection systems in the 1950s, while Francis M. Rogallo at Langley developed creative parasail concepts that informed the development of the recovery systems of numerous reentry vehicles.

The chapters that follow relate in a chronological manner the way in which NASA has approached the challenge of reentering the atmosphere after a space mission and the technologies associated with safely dealing with the friction of this encounter and the methods used for landing safely on Earth.

The first chapter explores the conceptual efforts to understand the nature of flight to and from space and the major developments in the technologies of reentry and landing that took place before the beginning of the space age in 1957.

Chapter 2 also investigates the methods of landing once a spacecraft reaches subsonic speeds. Once the orbital energy is converted and the heat of reentry dissipated, the spacecraft must still be landed gently in the ocean or on land. Virtually all of the early concepts for human space flight involve spaceplanes that flew on wings to a runway landing; Sänger’s antipodal bomber of the 1940s did so as did von Braun’s popular concepts. However, these proved impractical for launch vehicles available during the 1950s, and capsule concepts that returned to Earth via parachute proliferated largely because they represented the “art of the possible” at the time.

Chapter 3 tells the story of reentry from space and landing on Earth from the beginning of the space age through the end of the Apollo program. During that period, NASA and other agencies concerned with the subject developed capsules with blunt-body ablative heat shields and recovery systems that relied on parachutes. The Department of Defense tested this reentry concept publicly with Project SCORE in 1958 and employed it throughout the CORONA satellite reconnaissance program of the 1960s, snatching in midair return capsules containing unprocessed surveillance footage dangling beneath parachutes. With the Mercury program, astronauts rode a blunt-body capsule with an ablative heat shield to a water landing, where the Navy rescued them. Project Gemini eventually used a similar approach, but NASA engineers experimented with a Rogallo wing and a proposed landing at the Flight Research Center on skids similar to those employed on the X-15. When the Rogallo wing failed to make the rapid progress required, NASA returned to the parachute concept used in Mercury and essentially used the same approach in Apollo, although with greatly improved ablative heat shields.

At the same time, the DOD pursued a spaceplane concept with the X-20 Dyna-Soar orbital vehicle that would have replaced the ablative heat shield with a reusable metallic heat shield and a lifting reentry that allowed the pilot to fly the vehicle to a runway landing. This is also the general approach pursued by the DOD with its Aerothermodynamic Elastic Structural Systems Environmental Tests and Martin X-23A Precision Reentry Including Maneuvering reEntry vehicles. NASA and DOD also experimented with lifting body concepts.