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Review of NASA’s Exploration Technology Development Program: An Interim Report
Advanced composite structures. Exotic materials, such as lightweight composites, often promise great advantages on paper and sometimes in practice. It was not clear from the presentation how and where these composite materials were going to be applied throughout the Constellation program. The performance benefit or the figure of merit was not clearly identified. Composite materials may potentially provide significant advantages in weight reduction, but studies of system tradeoffs are needed to identify and quantify those gains.
No new facilities were identified as needed to validate performance capabilities.
Radiation shielding kit. The technology, which proposes a type of blanket or sleeping bag approach as a portable shield, is good as fundamental research. However, unless its specific application to various elements is identified, it is very difficult to see its impact on the exploration programs. The use of this kit was not compared with other competing options. What are the figures of merit?
Alignment with the Objectives of the Vision for Space Exploration: Yellow Flag
While it is not clear why some specific project work was selected, overall the project elements are proceeding in a timely manner and results are expected to be available to meet VSE and Constellation program schedules. However, the benefit of this work is limited by an apparent lack of specific requirements coming from the Constellation Project Office. The performance benefit for the VSE and Constellation programs may not be fully achieved. There appears to be little in the way of enabling technology in these project elements. Therefore, a strong push for these technologies by the customer is not apparent.
02 ABLATIVE THERMAL PROTECTION SYSTEM FOR THECREW EXPLORATION VEHICLE
Extremely large heat fluxes are experienced by the CEV during reentry from the Moon or Mars. An ablative heat shield is required for thermal protection. The heat shield design and qualification of the thermal protection system (TPS) material represent major technological challenges. The NASA team stated that the present TRL is 4; the TRL needs to be advanced to 6 to support the CEV.
The team is composed of NASA, the companies producing the materials, and the CEV contractor. The work is being carried out in a coordinated manner and, overall, is of good quality. The currently used metrics are appropriate. It appears that the arc-jet facility at Ames Research Center (ARC) will be upgraded, which will improve its flow simulation capabilities.
Material test specimens and TPS materials for the primary and backup CEV heat shields are being produced by aerospace companies. The CEV contractor has built a full-scale heat shield test article and will build the flight heat shield. These developments are being directed and reviewed by NASA to ensure coordinated consideration of reentry mechanical and thermal loads. There is no possibility of alternate technologies being developed within the ETDP. The plan is to have an acceptable TPS design by CEV Preliminary Design Review (PDR) and to have the technology matured by CEV Final Design Review (FDR).