SCIENTIFIC AND TECHNICAL AEROSPACE REPORTS

A Biweekly Publication of the National Aeronautics and Space Administration
VOLUME 44, ISSUE 12 - JUNE 20, 2006

18 SPACECRAFT DESIGN, TESTING AND PERFORMANCE
Includes satellites; space platforms; space stations; spacecraft systems and components such as thermal and environmental controls; and spacecraft control and stability characteristics.

For life support systems see 54 Man/System Technology and Life Support.

For related information see also 05 Aircraft Design, Testing and Performance; 39 Structural Mechanics; and 16 Space Transportation and Safety.

20060013651 NASA Marshall Space Flight Center, Huntsville, AL, USA

High-Resolution Inspection of the Space Shuttle External Tank Spray-on-Foam Insulation (SOFI) using Focused Millimeter Waves at D-Band (150 GHz)

Kharkovsky, S.; Zoughi, R.; Hepburn, F. L.; [2006]; 1 pp.; In English; American Society of Nondestructive Testing 15th Annual Research Symposium, 13-17 Mar. 2006, Orlando, FL, USA Contract(s)/Grant(s): NNM04AA15A; Copyright; Avail.: Other Sources; Abstract Only

Space Shuttle Columbia's catastrophic failure has been attributed to a piece of spray-on-foam insulation (SOFI) that was dislodged from the external tank and struck the leading edge of the left wing. A piece of SOFI was also dislodged in the recent Space Shuttle Discovery's flight. Clearly, there is a great and urgent need to inspect the external tank SOFI and other similar insulating structures (including the acreage heat tile) in a reliable and robust fashion. In the past two years, millimeter wave nondestructive testing methods, using both real and synthetic focusing techniques, have shown great potential for this purpose. Recently obtained real-focused images from several different and complex SOFI panels have demonstrated the utility of these methods as being viable, robust, repeatable, simple, portable and effective. D-band frequency range which covers a frequency spectrum of 110- 170 GHz is well-suited for this purpose given the nature of the foam which causes significant scattering at much higher frequencies. This paper presents the results of using continuous-wave (CW) reflectometry conducted on several typical and complex SOFI panes at 150 GHz. Author

External Tanks; Foams; Nondestructive Tests; Space Shuttles; Millimeter Waves; Inspection; High Resolution; Optical Measurement; Insulation

20060014004 NASA Johnson Space Center, Houston, TX, USA

Passive Stability on an Entry Vehicle to Enhance Crew Survival

Deger, Daniel J.; Hoffman, David; Crull, Tim; Cuthbert, Peter; Liama, Eduardo; Madsen, Chris; Stuart, Phil; Bryant, Lee; [2005]; 1 pp.; In English; 1st Space Exploration Conference Continuing the Voyage of Discovery, 30 Jan. - 1 Feb. 2005, Reston, VA, USA Contract(s)/Grant(s): 72-761-10; No Copyright; Avail.: Other Sources; Abstract Only

The most desirable crew survival feature for an entry vehicle is probably a full coverage escape system.With full overage escape, crew survival is maintained for a wide range of failures by the allowing the crew to escape from the failed vehicle and performing the entry to touchdown flight phase in an alternative system. However, there are considerable challenges in providing a separate entry capability, and for some programs, requiring full coverage escape could result in program cancellation. An alternative means of providing for crew survival if the flight control system fails is to design a return vehicle that can enter without active attitude control. A study was performed to assess the feasibility of performing a totally passive entry. Lift over drag has a major impact on performing a passive entry, so a parametric of three typical lift over drag concepts was performed. First an assessment of historical entry vehicles was completed. Second an assessment of end of mission entry trajectories and entry trajectories initiated from ascent abort profiles were made. Trajectories for a wide array of pitch, yaw, and roll rates were made. Third, six-degree-of freedom analyses of the entry were performed. FOP a truly passive return, the entry vehicle must trim in only the heat shield forward orientation. An assessment of the effect of center of gravity placement to achieve this orientation was made. Author

Escape Systems; Heat Shielding; Stability; Flight Control; Survival; Failure; Ascent; Flight Crews

20060014008 NASA Marshall Space Flight Center, Huntsville, AL, USA

The Evolution of Nondestructive Evaluation Methods for the Space Shuttle External Tank Thermal Protection System

Walker, James L.; Richter, Joel D.; [2006]; 1 pp.; In English; American Society for Nondestructive Testing 2006 Spring Conference, 13-17 Mar. 2006, Orlando, FL, USA; No Copyright; Avail.: Other Sources; Abstract Only

Three nondestructive evaluation methods are being developed to identify defects in the foam thermal protection system (TPS) of the Space Shuttle External Tank (ET). Shearography is being developed to identify shallow delaminations, shallow voids and crush damage in the foam while terahertz imaging and backscatter radiography are being developed to identify voids and cracks in thick foam regions. The basic theory of operation along with factors affecting the results of these methods will be described. Also, the evolution of these methods from lab tools to implementation on the ET will be discussed. Results from both test panels and flight tank inspections will be provided to show the range in defect sizes and types that can be readily detected. Author

Thermal Protection; External Tanks; Space Shuttles; Nondestructive Tests; Shearography; Delaminating; Voids; Damage; Radiography; Backscattering

20060015097 NASA Ames Research Center, Moffett Field, CA, USA,

Jet Propulsion Lab., California Inst. of Tech.,Pasadena, CA, USA, NASA Dryden Flight Research Center,

Edwards, CA, USA Integrated System Health Management (ISHM) Technology Demonstration Project Final Report Mackey, Ryan; Iverson, David; Pisanich, Greg; Toberman, Mike; Hicks, Ken; February 2006; 57 pp.; In English Contract(s)/Grant(s): NAS2-00065; WBS 21-723-27-01 Report No.(s): NASA/TM-2006-213482; No Copyright; Avail.: CASI: A04, Hardcopy

Integrated System Health Management (ISHM) is an essential capability that will be required to enable upcoming explorations mission systems such as the Crew Exploration Vehicle (CEV) and Crew Launch Vehicle (CLV), as well as NASA aeronautics missions. However, the lack of flight experience and available test platforms have held back the infusion by NASA Ames Research Center (ARC) and the Jet Propulsion Laboratory (JPL) of ISHM technologies into future space and aeronautical missions. To address this problem, a pioneer project was conceived to use a high-performance aircraft as a low-cost proxy to develop, mature, and verify the effectiveness of candidate ISHM technologies. Given the similarities between spacecraft and aircraft, an F/A-18 currently stationed at Dryden Flight Research Center (DFRC) was chosen as a suitable host platform for the test bed. This report describes how the test bed was conceived, how the technologies were integrated on to the aircraft, and how these technologies were matured during the project. It also describes the lessons learned during the project and a forward path for continued work. Author

Systems Integration; Aircraft Performance; Electric Propulsion; Launch Vehicles; Management Systems; Pioneer Project

20060016363 NASA Ames Research Center, Moffett Field, CA, USA

The TPS Advanced Development Project for CEV

Reuther, James; Wercinski, Paul; Venkatapathy, Ethiraj; Ellerby, Don; Raiche, George; Bowman, Lynn; Jones, Craig; Kowal, John; [2006]; 1 pp.; In English; National Space and Missile Materials Symposium, 26-30 Jun. 2006, Orlando, FL, USA; No Copyright; Avail.: Other Sources; Abstract Only

The CEV TPS Advanced Development Project (ADP) is a NASA in-house activity for providing two heatshield preliminary designs (a Lunar direct return as well as a LEO only return) for the CEV, including the TPS, the carrier structure, the interfaces and the attachments. The project s primary objective is the development of a single heatshield preliminary design that meets both Lunar direct return and LEO return requirements. The effort to develop the Lunar direct return capable heatshield is considered a high risk item for the NASA CEV development effort due to the low TRL (approx. 4) of the candidate TPS materials. By initiating the TPS ADP early in the development cycle, the intent is to use materials analysis and testing in combination with manufacturing demonstrations to reduce the programmatic risk of using advanced TPS technologies in the critical path for CEV.

Due to the technical and schedule risks associated a Lunar return heatshield, the ADP will pursue a parallel path design approach, whereby a back-up TPS/heatshield design that only meets LEO return requirements is also developed. The TPS materials and carrier structure design concept selections will be based on testing, analysis, design and evaluation of scalability and manufacturing performed under the ADP. At the TPS PDR, the preferred programmatic strategy is to transfer the continued (detailed) design, development, testing and evaluation (DDT&E) of both the Lunar direct and LEO return designs to a government/prime contractor coordinated sub-system design team. The CEV prime contractor would have responsibility for the continued heatshield sub-system development. Continued government participation would include analysis, testing and evaluation as well as decision authority at TPS Final System Decision (FSD) (choosing between the primary and back-up heatshields) occurring between TPS PDR and TPS Critical Design Review (CDR). After TPS FSD the prime CEV contractor will complete the detailed design, certification testing, procurement, and integration of the CEV TPS. Author

Heat Shielding; Design Analysis; Certification; Low Earth Orbits; Risk; Procurement

Source: NASA