Editing Atmospheric entry (section)

====SIRCA====
[[File:Ds 2.jpg|thumb|[[Deep Space 2]] [[Lander (spacecraft)|impactor]] aeroshell, a classic 45° sphere-cone with spherical section afterbody, enabling aerodynamic stability from atmospheric entry to surface impact]]
Silicone-impregnated reusable ceramic ablator (SIRCA) was also developed at NASA Ames Research Center and was used on the Backshell Interface Plate (BIP) of the ''[[Mars Pathfinder]]'' and [[Mars Exploration Rover]] (MER) aeroshells. The BIP was at the attachment points between the aeroshell's backshell (also called the afterbody or aft cover) and the cruise ring (also called the cruise stage). SIRCA was also the primary TPS material for the unsuccessful [[Deep Space 2]] (DS/2) Mars [[Lander (spacecraft)|impactor]] probes with their {{Convert|0.35|m|ft|-base-diameter|adj=mid|sp=us}} aeroshells. SIRCA is a monolithic, insulating material that can provide thermal protection through ablation. It is the only TPS material that can be machined to custom shapes and then applied directly to the spacecraft. There is no post-processing, heat treating, or additional coatings required (unlike Space Shuttle tiles). Since SIRCA can be machined to precise shapes, it can be applied as tiles, leading edge sections, full nose caps, or in any number of custom shapes or sizes. {{as of|1996}}, SIRCA had been demonstrated in backshell interface applications, but not yet as a forebody TPS material.<ref>Tran, Huy K., et al., "Silicone impregnated reusable ceramic ablators for Mars follow-on missions," AIAA-1996-1819, Thermophysics Conference, 31st, New Orleans, June 17–20, 1996.</ref>