Re-entry Missions

Abstract

After orbiting the spacecraft, in many cases the materials are to be brought back from space to Earth. It is also essential to bring back the humans safely from space after completion of the space exploration experiments. During the return of the vehicle from space, it re-enters the Earth’s atmosphere with orbital speed and remains in the atmosphere for the entire duration of the mission till the vehicle is brought to rest at the specified location. During this regime, the vehicle travels with very high hypersonic speeds at relatively lower altitudes and this causes harsh environments to the vehicle along with different complex flight regimes. Design of such a vehicle which has to fly safely in the severe operating environment with highly varying flight operating regimes along with large dispersions in both flight and vehicle parameters and ensuring the safe landing at the specified location is quite complex. All the reentry space transportation systems are having a wide range of flight regimes with large dispersions in flight parameters, severe flight environments and different functional requirements. For the case of reentry missions, the aerothermal operating environment is entirely different for different missions and strongly depends on the trajectory of a particular reentry mission which makes the vehicle design as unique for the specified reentry mission. The reentry systems are truly interdisciplinary with strong coupling between various vehicle systems viz., aerodynamic configuration, thermal protection systems, structure and vehicle trajectory. Therefore, integrated systems approach is essential for the optimum reentry systems design. This chapter addresses the design guidelines, complexity of the flight environment and the design for reentry systems. The reentry dynamics and reentry vehicle configuration aspects are discussed. The aerothermodynamics aspects which involve aerodynamic design, structural design, thermal environment and thermal protection system design of reentry vehicles are included. The details of the thermal protection systems are presented. The salient aspects of the trajectory design, reentry guidance schemes and mission management are highlighted.