Thermal Protection System Requirements for Future Planetary Entry and Aerocapture Missions

TL;DR

This paper compares thermal protection system requirements for future planetary entry and aerocapture missions, highlighting the capabilities of NASA's HEEET material to withstand extreme heat loads across different destinations.

Contribution

It introduces a comparative analysis of TPS requirements for various planets and evaluates HEEET's suitability for future missions using the AMAT tool.

Findings

HEEET can sustain large heat loads within acceptable mass fractions.

Aerocapture heat loads are significantly lower than probe entry.

TPS requirements vary greatly depending on planetary destination.

Abstract

Thermal protection systems are a critical component of planetary exploration, enabling probes to enter the atmosphere and perform in-situ measurements. The aero-thermal conditions encountered during entry are destination and vehicle dependent, ranging from relatively benign conditions at Mars and Titan, to extreme conditions at Venus and Jupiter. The thermal protection system is a single-point-of-failure for both entry probe and aerocapture missions, and hence must be qualified using ground tests to ensure mission success. The high density Carbon-Phenolic which was used in the Galileo and the Pioneer Venus missions is no longer available due to the lack of the manufacturing base for its raw materials. To address the need for Venus and outer planet missions, NASA has developed the Heatshield for Extreme Environment Entry Technology (HEEET). The present study uses the Aerocapture Mission Analysis Tool (AMAT) to perform a comparative study of the thermal protection system requirements for various planetary destinations and the applicability of HEEET for future entry and aerocapture missions. The heat rate and stagnation pressure for aerocapture is significantly less compared to probe entry. The large heat loads during aerocapture present a challenge, but HEEET is capable of sustaining large heat loads within a reasonable TPS mass fraction.