design. Multi-functional TPS and multi-layer insulation (MLI) systems that combine thermal, structural, micrometeoroid and orbital debris (MMOD), and crew radiation protection could provide significant weight savings and enable long-duration missions, and can also be used for planetary habitat thermal and multifunctional protection. This challenge is also ranked third by TA12.
5. Verification and Validation: Develop, verify, validate, and quantify uncertainty analysis requirements for new or improved comprehensive computer codes for thermal analysis.
Upgrades to predictive codes for ablation during re-entry heating are needed to include closely coupled multiphase ablation and radiative heating into the flow simulations, with careful attention given to verification, validation, and uncertainty quantification. All thermal analysis codes should include (1) verification that the codes have no internal errors, and accurately code the equations used for modeling and analysis; (2) predictions validating against all available experimental data, accounting for experimental error bands; and (3) quantifying the confidence in code predictions, accounting for uncertainties in the data used as model input, uncertainties in the mathematical models used in the analysis, and uncertainties caused by the numerical technique that is implemented (e.g., discretization errors in time and space). Without these attributes, the results generated by the codes are unreliable for design. This challenge is also addressed by TA10 and TA12.
6. Repair Capability: Develop in-space Thermal Protection System (TPS) repair capability.
Repair capability is especially important for long-duration missions, where no safe-haven repair facilities will be available. TPS repair developed for Space Shuttle Orbiter TPS (reinforced carbon-carbon/tiles) should be continued and expanded to provide a repair method for future spacecraft, both NASA and commercial.
7. Thermal Sensors. Enhance thermal sensor systems and measurement technologies.
Operational instrumentation is necessary to understand anomalies, material or performance degradation and performance enhancements, as well as for advanced science mission measurements. Ultra-lightweight sensor systems may provide data needed to identify on-orbit damage, measurement of liquid levels in a microgravity environment, in situ or self-repairing mechanisms, or adaptive control algorithms that can compensate for damage without repairing. Accurate instrumentation to monitor reentry TPS performance is necessary to validate emerging predictive codes for heat shield design. Each of these would improve flight safety and the probability of mission success.
QFD MATRIX AND NUMERICAL RESULTS FOR TA14
The averaged quality function deployment (QFD) matrix for the nine level 3 technologies in TA14 is given in Figure Q.1.
The weighted scores for all level 3 technologies evaluated with the QFD approach are listed in Figure Q.2. 14.3.1 Ascent/Entry TPS received a much higher score than all other level 3 technologies, creating an obvious break point in assigning the high rating. 14.1.2 Active Thermal Control is a needed technology to support zero boil off of cryogenic fluids. Though 14.1.2 Active Thermal Control did not achieve the high rating of 14.3.1 Ascent/Entry TPS, it is considered an enabling technology for a wide variety of long-duration missions, and was thus also assigned high priority. These two technologies are therefore discussed at length. The other seven technologies were rated as “Medium” or “Low.”
CHALLENGES VERSUS TECHNOLOGIES
In Figure Q.3, the technologies are listed in descending priority on the vertical columns, and the challenges are shown in the horizontal top row. The correlation between the two is indicated by high correlation (solid symbols), weak correlation (open symbols) or little or no correlation (no symbols). It is seen that the challenges correlate to