. "4 Management and Execution of the Exploration Technology Development Program." A Constrained Space Exploration Technology Program: A Review of NASA's Exploration Technology Development Program. Washington, DC: The National Academies Press, 2008.
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A Constrained Space Exploration Technology Program: A Review of NASA’s Exploration Technology Development Program
engineering practices (such as testing to understand why systems were not performing in accordance with requirements).”13
Testing is needed to specifically address the risks inherent with any new technology. The lack of sufficient testing in the current ETDP poses the threat that technologies will not ultimately be available to be integrated into the Constellation Program, which increases overall programmatic risk.
The lack of systems testing affects how requirements from the broader system can be integrated into the technology at an early enough time to impact the technology’s development. The lack of systems testing also limits the rate at which the technology will mature, which affects how their importance is viewed. Early identification of issues from testing greatly reduces programmatic costs.
The committee identified a lack of sufficient testing (ground or flight) in 12 ETDP projects (Ablative Thermal Protection System for the Crew Exploration Vehicle, Lunar Dust Mitigation, Cryogenic Fluid Management, High-Performance and Radiation-Hardened Electronics, Intelligent Software Design, Autonomous Landing and Hazard Avoidance Technology, Automated Rendezvous and Docking Sensor Technology, Extravehicular Activity Technologies, International Space Station Research, In Situ Resource Utilization, Fission Surface Power, and Human-Robotic Systems/Analogs). In several projects the missing tests will prevent the achievement of TRL 6 in key technologies and will risk their incorporation into the Constellation Program architecture. The reason for omitting these tests is usually a lack of time (scheduling) and/or a lack of funding to develop the needed test facilities or to carry out necessary flight tests.
The present ETDP lacks the systematic progression of testing, especially in a flight-like environment, needed for the following purposes: (1) to decide which of the alternative technologies should be brought forward and how they will have to be modified to be successful in their final form, (2) to ensure that the different technologies mature and are ready when they are needed, and (3) to validate that technologies will function as expected when integrated into the larger system and operating in the space and lunar environments.
Within the ETDP there appears to be no consideration of using missions in the Lunar Precursor Robotic Program to demonstrate technologies that are candidates for the crewed missions. This is an example of the need for a tighter coupling to occur between the Lunar Precursor Robotic Program and the ETDP, both in the ESMD Advanced Capabilities area. At the time of this review the Lunar Precursor Robotic Program had been limited to the Lunar Reconnaissance Orbiter (LRO) and the Lunar Crater Observation and Sensing Satellite (LCROSS). However, with the Science Mission Directorate’s recent selection of the Gravity Recovery and Interior Laboratory for the Discovery program (whose gravity mapping science is also important to lunar navigation engineering) and the identification of some other small lunar missions (an orbiter and a lander), there is evidence that NASA may look beyond LRO and LCROSS in terms or robotic precursor missions. The question of whether these missions could also serve a technology demonstration role is worth investigating. Apollo had numerous precursor missions before men headed to the Moon. While that may not be necessary for this return to the Moon, some technology demonstration by robotic precursors is likely prudent.
Three of the ETDP projects (Lunar Dust Mitigation, In Situ Resource Utilization, and Human-Robotic Systems/Analogs) require but do not at present include tests in a realistic lunar environment including the effects of dust, vacuum, and lunar thermal cycles. The Lunar Dust Mitigation project requires tests at full scale. The construction of a new facility or a significant upgrading of an existing facility would enable needed tests for all three projects. Such tests could also be performed during early lunar missions in preparation for the later, longer-duration missions.
The most important flight test is that required for the Orion reentry heat shield. Even though 40 years have elapsed since the Apollo 4 flight test and the state of the art in heat shield design has advanced significantly, it is still not possible to simulate a lunar-return Earth entry in ground-based facilities. Within the present state of the art, it is not possible to build ground-test facilities that will duplicate (or even adequately approximate) reentry flight conditions. Only a reentry flight test at lunar-return velocity and at a scale sufficient to assess the effects of joints and gaps between the heat shield panels will qualify the heat shield for use on a crewed lunar-return mission.
Columbia Accident Investigation Board and the National Aeronautics and Space Administration, Columbia Accident Investigation BoardReport, U.S. Government Printing Office, Washington, D.C., 2003, available at http://caib.nasa.gov/.