A Hypersonic Parachute for Low-Temperature Atmospheric Reentry

Abstract - Atmospheric re-entry, even when initiated from a circular low-Earth orbit, requires heavy heat shields, ablative materials or radiative dissipation techniques. Semi-analytical and numerical simulations of the atmospheric re-entry from low-Earth orbits of a capsule with a 20-km, attached, heat resistant tether have shown that the thermal input flux on the capsule is reduced by more than one order of magnitude with respect to a comparable re-entry without tether. Long tethers have low ballistic coefficients and a large surface for heat dissipation. Moreover, a long tether is stabilized by gravity gradient and consequently tends to maintain a high angle of attack with respect to the wind velocity. The exposed surface of a 20-km-long 1-mm diameter tether is 20 m2, which is much larger than the cross section of a re-entry capsule. The resulting strong drag decelerates the capsule during re-entry like a conceivable hypersonic parachute would do. This paper describes the methods and results of the simulation of the SEDS endmass re-entry with different tethers.