New TPS Materials for Aerocapture

摘要

Many planetary probes, landers and aerocapture concepts are conceived for entry trajectories where peak convective heat flux is in the range 150-400 W/cm~2. This may be too severe an environment for either reusable or low-density ablative materials. The high-density ablatives will work in such environments but the associated TPS weight requirements can be prohibitive. Unfortunately, there are few, if any, well-understood materials that provide reliable, predictable ablative performance for the 150-400 W/cm~2 regime while still providing weight efficient TPS solutions. JPL has recently been evaluating an Earth aerocapture demonstration at an entry velocity of ≈ 10 km/s. TPS thickness and areal weight requirements were determined for current ablative TPS candidates (e.g., SLA-561V, PICA) where, for the large integrated heat loads associated with aerocapture. it is shown that some of these materials may not provide efficient thermal protection. A new concept, employing a low catalycity, high emissivity coating on a low-density ceramic tile is evaluated and shown to provide significant benefits for such missions.