A HYPERSONIC PARACHUTE FOR LOW-TEMPERATURE REENTRY

Atmospheric re-entry, even when initiated from a circular low-Earth or bit, requires heavy heat shields, ablative materials or radiative diss ipation techniques. Semi-analytical and numerical simulations of the a tmospheric re-entry from low-Earth orbits of a capsule with a 20-km, a ttached, heat resistant tether have shown that the thermal input flux on the capsule is reduced by more than one order of magnitude with res pect to a comparable re-entry without tether. Long tethers have low ba llistic coefficients and a large surface for heat dissipation. Moreove r, a long tether is stabilized by gravity gradient and consequently te nds to maintain a high angle of attack with respect to the wind veloci ty. The exposed surface of a 20-km-long l-mm diameter tether is 20 m(2 ), 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 wi th different tethers.