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Bistatic and Multistatic Radar: Surveillance, Countermeasures, and Radar Cross Sections. (Latest citations from the Aerospace Database)

The bibliography contains citations concerning the design, development, testing, and evaluation of bistatic and multistatic radar used in surveillance and countermeasure technology. Citations discuss radar cross sections, target recognition and characteristics, ghost recognition, motion image compensation, and wavelet analysis. Stealth aircraft design, stealth target tracking, synthetic aperture radar, and space applications are examined.

MULTISTATIC RADAR↗

NASA Crew Launch Vehicle Approach Builds on Lessons from Past and Present Missions

The United States Vision for Space Exploration, announced in January 2004, outlines the National Aeronautics and Space Administration's (NASA) strategic goals and objectives, including retiring the Space Shuttle and replacing it with a new human-rated system suitable for missions to the Moon and Mars. The Crew Exploration Vehicle (CEV) that the new Crew Launch Vehicle (CLV) lofts into space early next decade will initially ferry astronauts to the International Space Station and be capable of carrying crews back to lunar orbit and of supporting missions to Mars orbit. NASA is using its extensive experience gained from past and ongoing launch vehicle programs to maximize the CLV system design approach, with the objective of reducing total lifecycle costs through operational efficiencies. To provide in-depth data for selecting this follow-on launch vehicle, the Exploration Systems Architecture Study was conducted during the summer of 2005, following the confirmation of the new NASA Administrator. A team of aerospace subject matter experts used technical, budget, and schedule objectives to analyze a number of potential launch systems, with a focus on human rating for exploration missions. The results showed that a variant of the Space Shuttle, utilizing the reusable Solid Rocket Booster as the first stage, along with a new upper stage that uses a derivative of the RS-25 Space Shuttle Main Engine to deliver 25 metric tons to low-Earth orbit, was the best choice to reduce the risks associated with fielding a new system in a timely manner. The CLV Project, managed by the Exploration Launch Office located at NASA's Marshall Space Flight Center, is leading the design, development, testing, and operation of this new human-rated system. The CLV Project works closely with the Space Shuttle Program to transition hardware, infrastructure, and workforce assets to the new launch system . leveraging a wealth of lessons learned from Shuttle operations. The CL V is being designed to reduce costs through a number of methods, ranging from validating requirements to conducting trades studies against the concept design. Innovations such as automated processing will build on lessons learned from the Shuttle, other launch systems, Department of Defense operations experience, and subscale flight tests such as the Delta Clipper-Experimental Advanced (DCXA) vehicle operations that utilized minimal touch labor, automated cryogen ic propellant loading , and an 8-hour turnaround for a cryogenic propulsion system. For the CLV, the results of hazard analyses are contributing to an integrated vehicle health monitoring system that will troubleshoot anomalies and determine which ones can be solved without human intervention. Such advances will help streamline the mission operations process for pilots and ground controllers alike. In fiscal year 2005, NASA invested approximately $4.5 billion of its $16 bill ion budget on the Space Shuttle. The ultimate goal of the CLV Project is to deliver a safe, reliable system designed to minimize lifecycle costs so that NASA's budget can be invested in missions of scientific discovery. Lessons learned from developing the CLV will be applied to the growth path for future systems, including a heavy lift launch vehicle.

Dumbacher, Daniel L.↗

CFS Test Framework

NASA's Core Flight System (cFS) provides a generic flight software framework architecture for developing flight software. As the cFS framework has gained popularity over the years within the flight software community, supporting software tools have been developed to assist in the design, development, testing and verification of flight software. The cFS Test Framework (CTF) is a recently developed cFS tool with capabilities to develop and run automated test and verification scripts against flight software targets. The CTF tool parses and executes JSON-based test scripts containing test instructions, while logging and reporting the results. CTF utilizes a plugin-based architecture to allow developers to extend CTF with new test instructions, external interfaces, and custom functionality. To interface with flight software, CTF parses a set of CCSDS message definition files to create the necessary command and telemetry structures for use during the test run. Additionally, CTF also supports interfacing with multiple cFS instances, allowing a test script to verify requirements that involve multiple flight software targets. Lastly, CTF provides support for executing test scripts against FSW running on remote or embedded hardware. This allows CTF to execute the same test scripts across different target configurations throughout the development process. In this presentation, we will introduce the cFS Test Framework (CTF) architecture, discuss the history of cFS testing frameworks, and present the features and capabilities currently provided by CTF. Lastly, we will show a demo of the CTF tool being used to execute test scripts against flight software.

cfs↗

cFS Test Framework (CTF)

NASA's Core Flight System (cFS) provides a generic flight software framework architecture for developing flight software. As the cFS framework has gained popularity over the years within the flight software community, supporting software tools have been developed to assist in the design, development, testing and verification of flight software. The cFS Test Framework (CTF) is a recently developed cFS tool with capabilities to develop and run automated test and verification scripts against flight software targets. The CTF tool parses and executes JSON-based test scripts containing test instructions, while logging and reporting the results. CTF utilizes a plugin-based architecture to allow developers to extend CTF with new test instructions, external interfaces, and custom functionality. To interface with flight software, CTF parses a set of CCSDS message definition files to create the necessary command and telemetry structures for use during the test run. Additionally, CTF also supports interfacing with multiple cFS instances, allowing a test script to verify requirements that involve multiple flight software targets. Lastly, CTF provides support for executing test scripts against FSW running on remote or embedded hardware. This allows CTF to execute the same test scripts across different target configurations throughout the development process. In this presentation, we will introduce the cFS Test Framework (CTF) architecture, discuss the history of cFS testing frameworks, and present the features and capabilities currently provided by CTF. Lastly, we will show a demo of the CTF tool being used to execute test scripts against flight software.

Aly I Shehata↗

Launch Vehicle Sizing Benefits Utilizing Main Propulsion System Crossfeed and Project Status

To meet the goals for a next generation Reusable Launch Vehicle (RLV), a unique propulsion feed system concept was identified using crossfeed between the booster and orbiter stages that could reduce the Two-Stage-to-Orbit (TSTO) vehicle weight and Design, Development, Test and Evaluation (DDT&E) costs by approximately 25%, while increasing safety and reliability. The Main Propulsion System (MPS) crossfeed water demonstration test program addresses all activities required to reduce the risks for the MPS crossfeed system from a Technology Readiness Level (TRL) of 2 to 4 by the completion of testing and analysis by June 2003. During the initial period, that ended in March 2002, a subscale water flow test article was defined. Procurement of a subscale crossfeed check valve was initiated and the specifications for the various components were developed. The fluid transient and pressurization analytical models were developed separately and successfully integrated. The test matrix for the water flow test was developed to correlate the integrated model. A computational fluid dynamics (CFD) model of the crossfeed check valve was developed to assess flow disturbances and internal flow dynamics. Based on the results, the passive crossfeed system concept was very feasible and offered a safe system to be used in an RLV architecture. A water flow test article was designed to accommodate a wide range of flows simulating a number of different types of propellant systems. During the follow-on period, the crossfeed system model will be further refined, the test article will be completed, the water flow test will be performed, and finally the crossfeed system model will be correlated with the test data. This validated computer model will be used to predict the full-scale vehicle crossfeed system performance.

Chandler, Frank↗

SMART: The Future of Spaceflight Avionics

A novel avionics approach is necessary to meet the future needs of low cost space and lunar missions that require low mass and low power electronics. The current state of the art for avionics systems are centralized electronic units that perform the required spacecraft functions. These electronic units are usually custom-designed for each application and the approach compels avionics designers to have in-depth system knowledge before design can commence. The overall design, development, test and evaluation (DDT&E) cycle for this conventional approach requires long delivery times for space flight electronics and is very expensive. The Small Multi-purpose Advanced Reconfigurable Technology (SMART) concept is currently being developed to overcome the limitations of traditional avionics design. The SMART concept is based upon two multi-functional modules that can be reconfigured to drive and sense a variety of mechanical and electrical components. The SMART units are key to a distributed avionics architecture whereby the modules are located close to or right at the desired application point. The drive module, SMART-D, receives commands from the main computer and controls the spacecraft mechanisms and devices with localized feedback. The sensor module, SMART-S, is used to sense the environmental sensors and offload local limit checking from the main computer. There are numerous benefits that are realized by implementing the SMART system. Localized sensor signal conditioning electronics reduces signal loss and overall wiring mass. Localized drive electronics increase control bandwidth and minimize time lags for critical functions. These benefits in-turn reduce the main processor overhead functions. Since SMART units are standard flight qualified units, DDT&E is reduced and system design can commence much earlier in the design cycle. Increased production scale lowers individual piece part cost and using standard modules also reduces non-recurring costs. The benefit list continues, but the overall message is already evident: the SMART concept is an evolution in spacecraft avionics. SMART devices have the potential to change the design paradigm for future satellites, spacecraft and even commercial applications.

Alhorn, Dean C.↗

Flight control system development and flight test experience with the F-111 mission adaptive wing aircraft

The wing on the NASA F-111 transonic aircraft technology airplane was modified to provide flexible leading and trailing edge flaps. This wing is known as the mission adaptive wing (MAW) because aerodynamic efficiency can be maintained at all speeds. Unlike a conventional wing, the MAW has no spoilers, external flap hinges, or fairings to break the smooth contour. The leading edge flaps and three-segment trailing edge flaps are controlled by a redundant fly-by-wire control system that features a dual digital primary system architecture providing roll and symmetric commands to the MAW control surfaces. A segregated analog backup system is provided in the event of a primary system failure. This paper discusses the design, development, testing, qualification, and flight test experience of the MAW primary and backup flight control systems.

Larson, R. R.↗

Flight control system development and flight test experience with the F-111 mission adaptive wing aircraft

The wing on the NASA F-111 transonic aircraft technology airplane was modified to provide flexible leading and trailing edge flaps. This wing is known as the mission adaptive wing (MAW) because aerodynamic efficiency can be maintained at all speeds. Unlike a conventional wing, the MAW has no spoilers, external flap hinges, or fairings to break the smooth contour. The leading edge flaps and three-segment trailing edge flaps are controlled by a redundant fly-by-wire control system that features a dual digital primary system architecture providing roll and symmetric commands to the MAW control surfaces. A segregated analog backup system is provided in the event of a primary system failure. This paper discusses the design, development, testing, qualification, and flight test experience of the MAW primary and backup flight control systems.

Larson, R. R.↗

Guidance, Navigation and Control (GN&C): Best Practices for Human-Rated Spacecraft Systems

In 2007 the NESC completed an in-depth assessment to identify, define and document engineering considerations for the Design Development Test and Evaluation (DDT&E) of human-rated spacecraft systems. This study had been requested by the Astronaut Office at JSC to help them to better understand what is required to ensure safe, robust, and reliable human-rated spacecraft systems. The 22 GN&C engineering Best Practices described in this paper are a condensed version of what appears in the NESC Technical Report. These Best Practices cover a broad range from fundamental system architectural considerations to more specific aspects (e.g., stability margin recommendations) of GN&C system design and development. 15 of the Best Practices address the early phases of a GN&C System development project and the remaining 7 deal with the later phases. Some of these Best Practices will cross-over between both phases. We recognize that this set of GN&C Best Practices will not be universally applicable to all projects and mission applications.

Lebsock, Ken↗

Hydrocarbon Rocket Technology Impact Forecasting

Ever since the Apollo program ended, the development of launch propulsion systems in the US has fallen drastically, with only two new booster engine developments, the SSME and the RS-68, occurring in the past few decades.1 In recent years, however, there has been an increased interest in pursuing more effective launch propulsion technologies in the U.S., exemplified by the NASA Office of the Chief Technologist s inclusion of Launch Propulsion Systems as the first technological area in the Space Technology Roadmaps2. One area of particular interest to both government agencies and commercial entities has been the development of hydrocarbon engines; NASA and the Air Force Research Lab3 have expressed interest in the use of hydrocarbon fuels for their respective SLS Booster and Reusable Booster System concepts, and two major commercially-developed launch vehicles SpaceX s Falcon 9 and Orbital Sciences Antares feature engines that use RP-1 kerosene fuel. Compared to engines powered by liquid hydrogen, hydrocarbon-fueled engines have a greater propellant density (usually resulting in a lighter overall engine), produce greater propulsive force, possess easier fuel handling and loading, and for reusable vehicle concepts can provide a shorter turnaround time between launches. These benefits suggest that a hydrocarbon-fueled launch vehicle would allow for a cheap and frequent means of access to space.1 However, the time and money required for the development of a new engine still presents a major challenge. Long and costly design, development, testing and evaluation (DDT&E) programs underscore the importance of identifying critical technologies and prioritizing investment efforts. Trade studies must be performed on engine concepts examining the affordability, operability, and reliability of each concept, and quantifying the impacts of proposed technologies. These studies can be performed through use of the Technology Impact Forecasting (TIF) method. The Technology Impact Forecasting method is a normative forecasting technique that allows the designer to quantify the effects of adding new technologies on a given design. This method can be used to assess and identify the necessary technological improvements needed to close the gap that exists between the current design and one that satisfies all constraints imposed on the design. The TIF methodology allows for more design knowledge to be brought to the earlier phases of the design process, making use of tools such as Quality Function Deployments, Morphological Matrices, Response Surface Methodology, and Monte Carlo Simulations.2 This increased knowledge allows for more informed decisions to be made earlier in the design process, resulting in shortened design cycle time. This paper will investigate applying the TIF method, which has been widely used in aircraft applications, to the conceptual design of a hydrocarbon rocket engine. In order to reinstate a manned presence in space, the U.S. must develop an affordable and sustainable launch capability. Hydrocarbon-fueled rockets have drawn interest from numerous major government and commercial entities because they offer a low-cost heavy-lift option that would allow for frequent launches1. However, the development of effective new hydrocarbon rockets would likely require new technologies in order to overcome certain design constraints. The use of advanced design methods, such as the TIF method, enables the designer to identify key areas in need of improvement, allowing one to dial in a proposed technology and assess its impact on the system. Through analyses such as this one, a conceptual design for a hydrocarbon-fueled vehicle that meets all imposed requirements can be achieved.

Stuber, Eric↗

Enabling and Enhancing Space Mission Success and Reduction of Risk through the Application of an Integrated Data Architecture

The engineering phases of design, development, test, and evaluation (DDT and E) and subsequent planning, preparation, and operation (Ops) of space vehicles in a complex and distributed environment requires massive and continuous flows of information across the enterprise and across temporal stages of the vehicle lifecycle. The resulting capabilities at each subsequent stage depend in part on the capture, preparation, storage, and subsequent provision of information from prior stages. The United States National Aeronautics and Space Administration (NASA) is currently designing a fleet of new vehicles that will replace the Space Shuttle and expand space operations and exploration capabilities. This includes the 2 stage human rated lift vehicle Ares 1 and its associated crew vehicle the Orion, and a service module; the heavy lift cargo vehicle, Ares 5, and an associated cargo stage known as the Earth Departure Stage; and a Lunar Lander vehicle that contains a descent stage, and ascent stage, and a habitation module. A variety of concurrent assorted ground operations infrastructure including software and facilities are also being developed, assorted technology and assembly designs and development for equipment such as EVA suits, life support systems, command and control technologies are also in the pipeline. The development is occurring in a distributed manner, with project deliverables being contributed by a large and diverse assortment of vendors and most space faring nations. Critical information about all of the components, software, and procedures must be shared during the DDT and E phases and then made readily available to the mission operations staff for access during the planning, preparation, and operations phases, and also need to be readily available for system to system interactions. The Constellation Data Systems Project (CxDS) is identifying the needs, and designing and deploying systems and processes to support these needs. This paper details the steps and processes that NASA is applying within the Constellation Program to manage this data and information, and to insure that the correct information is available, correctly annotated, and can be provisioned digitally to enhance response times, and support engineering analysis and anomaly resolution.

Brummett, Robert C.↗

Failure analysis of solid rocket apogee motors

The analysis followed five selected motors through initial design, development, test, qualification, manufacture, and final flight reports. An audit was conducted at the manufacturing plants to complement the literature search with firsthand observations of the current philosophies and practices that affect reliability of the motors. A second literature search emphasized acquisition of spacecraft and satellite data bearing on solid motor reliability. It was concluded that present practices at the plants yield highly reliable flight hardware. Reliability can be further improved by new developments of aft-end bonding and initiator/igniter nondestructive test methods, a safe/arm device, and an insulation formulation. Minimum diagnostic instrumentation is recommended for all motor flights. Surplus motors should be used in margin testing. Criteria should be established for pressure and zone curing. The motor contractor should be represented at launch. New design analyses should be made of stretched motors and spacecraft/motor pairs.

Martin, P. J.↗

Space Shuttle Solid Rocket Booster decelerator subsystem - Air drop test vehicle/B-52 design

The air drop development test program for the Space Shuttle Solid Rocket Booster Recovery System required the design of a large drop test vehicle that would meet all the stringent requirements placed on it by structural loads, safety considerations, flight recovery system interfaces, and sequence. The drop test vehicle had to have the capability to test the drogue and the three main parachutes both separately and in the total flight deployment sequence and still be low-cost to fit in a low-budget development program. The design to test large ribbon parachutes to loads of 300,000 pounds required the detailed investigation and integration of several parameters such as carrier aircraft mechanical interface, drop test vehicle ground transportability, impact point ground penetration, salvageability, drop test vehicle intelligence, flight design hardware interfaces, and packaging fidelity.

Runkle, R. E.↗

Launch Vehicle Propulsion Design with Multiple Selection Criteria

The approach and techniques described herein define an optimization and evaluation approach for a liquid hydrogen/liquid oxygen single-stage-to-orbit system. The method uses Monte Carlo simulations, genetic algorithm solvers, a propulsion thermo-chemical code, power series regression curves for historical data, and statistical models in order to optimize a vehicle system. The system, including parameters for engine chamber pressure, area ratio, and oxidizer/fuel ratio, was modeled and optimized to determine the best design for seven separate design weight and cost cases by varying design and technology parameters. Significant model results show that a 53% increase in Design, Development, Test and Evaluation cost results in a 67% reduction in Gross Liftoff Weight. Other key findings show the sensitivity of propulsion parameters, technology factors, and cost factors and how these parameters differ when cost and weight are optimized separately. Each of the three key propulsion parameters; chamber pressure, area ratio, and oxidizer/fuel ratio, are optimized in the seven design cases and results are plotted to show impacts to engine mass and overall vehicle mass.

Shelton, Joey D.↗

Equivalent Mass versus Life Cycle Cost for Life Support Technology Selection

The decision to develop a particular life support technology or to select it for flight usually depends on the cost to develop and fly it. Other criteria - performance, safety, reliability, crew time, and risk - are considered, but cost is always an important factor. Because launch cost accounts for most of the cost of planetary missions, and because launch cost is directly proportional to the mass launched, equivalent mass has been used instead of cost to select life support technology. The equivalent mass of a life support system includes the estimated masses of the hardware and of the pressurized volume, power supply, and cooling system that the hardware requires. The equivalent mass is defined as the total payload launch mass needed to provide and support the system. An extension of equivalent mass, Equivalent System Mass (ESM), has been established for use in Advanced Life Support. A crew time mass-equivalent and sometimes other non-mass factors are added to equivalent mass to create ESM. Equivalent mass is an estimate of the launch cost only. For earth orbit rather than planetary missions, the launch cost is usually exceeded by the cost of Design, Development, Test, and Evaluation (DDT&E). Equivalent mass is used only in life support analysis. Life Cycle Cost (LCC) is much more commonly used. LCC includes DDT&E, launch, and operations costs. Since LCC includes launch cost, it is always a more accurate cost estimator than equivalent mass. The relative costs of development, launch, and operations vary depending on the mission design, destination, and duration. Since DDT&E or operations may cost more than launch, LCC may give a more accurate cost ranking than equivalent mass. To be sure of identifying the lowest cost technology for a particular mission, we should use LCC rather than equivalent mass.

Jones, Harry↗

Building on 50 Years of Mission Operations Experience for a New Era of Space Exploration

The U.S. National Space Policy, I the 14-nation Global Exploration Strategy,2 and the National Aeronautics and Space Administration's (NASA) 2006 Strategic Plan3 provide foundational direction for far-ranging missions, from safely flying the Space Shuttle and completing construction of the International Space Station by 2010, to fielding a next generation space transportation system consisting of the Ares I Crew Launch Vehicle!Orion Crew Exploration Vehicle and the Ares V Cargo Launch Vehicle!Altair Lunar Lander (fig. 1). Transportation beyond low-Earth orbit will open the frontier for a lunar outpost, where astronauts will harness in-situ resources while exploring this 4 billion-year-old archaeological site, which may hold answers to how the Earth and its satellite were formed. Ultimately, this experience will pave the way for the first human footprint on Mars. In October 2007, NASA" announced assignments for this lunar exploration work.4 The Marshall Space Flight Center is responsible for designing, developing, testing, and evaluating the Ares I and Ares V, which are Space Shuttle derived launch vehicles, along with a number of lunar tasks. The Marshall Center's Engineering Directorate provides the skilled workforce and unique manufacturing, testing, and operational infrastructure needed to deliver space transportation solutions that meet the requirements stated in the Constellation Architecture Requirements Document (CARD). While defining design reference missions to the Station and the Moon, the CARD includes goals that include reducing recurring and nonrecurring costs, while increasing safety and reliability. For this reason, future systems are being designed with operability considerations and lifecycle expenses as independent variables in engineering trade studies.

Onken, Jay F.↗

Mars Sample Return: Grand Challenge for EDL

A year ago, I gave a talk in anticipation of a Mars Sample Return effort at the 9th Ablation Workshop. Since then a lot has happened. "April of this year, after a year of study phase, NASA and ESA (European Space Agency) signed a Statement of Intent (SOI) to jointly develop a Mars Sample Return plan to be submitted to their respective authorities by the end of 2019. This signing is historic, as it signals the desire, the readiness, and the willingness to work together to execute this inspiring mission, we all have the opportunity to tackle this grand challenge. We have the scientific and engineering maturity to identify the critical technologies ready to be applied, and with discipline this campaign can be executed affordably," Jim Watzin, Mars Program Executive, NASA. NASA Centers with JPL (Jet Propulsion Laboratory) leading the charge is in the midst of a pre-formulation phase for executing a Mars Sample Return before the end of next decade. The proposed talk builds on the previous year talk. In light of the agreement between NASA and ESA, NASA has assumed the responsibilities for developing the earth entry vehicle (EEV) that will fly along with a European Spacecraft and return with the sample from Mars. EEV will be deployed for entry into earth. The EEV design, development, testing and certification have to result in a highly reliable sample return system. The entire architecture has to be demonstrated to meet the planetary protection requirement. NASA is considering two distinctly different earth entry vehicle architectures and with each choice, many different ablative TPS (Thermal Protective Shield) candidates. As a result of the NASA-ESA ongoing studies, some of the key entry conditions and design requirements are better understood today and more are being scoped out. The heat-shield ablative TPS choice need to be done with a good understanding as it plays a very significant role in determining the robustness of the EEV. Knowledge about how materials and system perform, and how the features could become flaws and how flaws lead to failure, etc. need to be clearly understood and the knowledge then need to be used to down select the TPS. This proposed talk will provide greater insight into the progress being made and the challenges that need to be tackled.

Mars Sample Return: Grand Challenge for EDL↗

The First Year in Review: NASA's Ares I Crew Launch Vehicle and Ares V Cargo Launch Vehicle

The U.S. Vision for Space Exploration guides NASA's challenging missions of scientific discovery.' Developing safe, reliable, and affordable space transportation systems for the human and robotic exploration of space is a key component of fulfilling the strategic goals outlined in the Vision, as well as in the U.S. Space Policy. In October 2005, the Exploration Systems Mission Directorate and its Constellation Program chartered the Exploration Launch Projects Office, located at the Marshall Space Flight Center, to design, develop, test, and field a new generation of launch vehicles that would fulfill customer and stakeholder requirements for trips to the Moon, Mars, and beyond. The Ares I crew launch vehicle is slated to loft the Orion crew exploration vehicle to orbit by 2014, while the heavy-lift Ares V cargo launch vehicle will deliver the lunar lander to orbit by 2020 (Fig. 1). These systems are being designed to empower America's return to the Moon to prepare for the first astronaut on Mars. The new launch vehicle designs now under study reflect almost 50 years of hard-won experience gained from the Saturn's missions to the Moon in the late 1960s and early 1970s, and from the venerable Space Shuttle, which is due to be retired by 2010.

Dumbacher, Daniel L.↗