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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 415 records · Page 23
All sourcesNASA NTRSDOE OSTI
NASA NTRSDate not supplied

Swift Mission Gyro Patch and Re-Calibration Without A Calibration Campaign

The Swift spacecraft has three Two-Axis-Rate-Assemblies (TARAs) (designated as TARA 1, TARA 2, and TARA 3, and generically referred to as gyros) which until March of 2024 were all used in rate estimation as an operational workaround (dubbed “corrector-gyro”) of a software defect discovered in 2007. TARA 1 performance degraded throughout 2023 and 2024, making it an unreliable rate source. It was determined that shifting TARA 1 to be the corrector-gyro and using mainly TARAs 2 and 3, with the existing flight software (FSW) defect, would not meet performance requirements for science operations. Rather the FSW was patched to remove the defect found in 2007. This patch was delivered by the vendor in 2009, but was not fully tested or installed at that time. A decision was made in 2024 to install the patch despite limited simulation and testing capabilities. The problem facing the team was to come up with a set of alignment parameters that would work with the new patch, using data from the spacecraft operating normally in the old configuration. Calibration activities would have been possible in either the old or new FSW configuration, but were ultimately deemed unnecessary, saving staff time and pre-serving time on the spacecraft for science data collection. This paper describes the old and new FSW configurations related to gyro processing and alignment, and how the raw gyro and star tracker data from normal operation were used with a multidimensional unconstrained nonlinear minimization in MATLAB (Nelder-Mead1) to produce a fully calibrated set of gyro alignment parameters compatible with the patched FSW. Flight data is presented showing that not only did the process work, it improved performance significantly, rivaling the best slew performance of the mission to date.

MATLAB↗
NASA NTRS1983

Stress testing of digital flight-control system software

A technique for dynamically testing digital flight-control system software on a module-by-module basis is described. Each test module is repetitively executed faster than real-time with an exhaustive input sequence. Outputs of the test module are compared with outputs generated by an alternate, simpler implementation for the same input data. Discrepancies between the two sets of output indicate the possible presence of a software error. The results of an implementation of this technique in the Digital Flight-Control System Software Verification Laboratory are discussed.

Rajan, N.↗
NASA NTRS2017

NASA's Space Launch System: Progress Report

NASA and its commercial industry team achieved significant progress in 2016 in manufacturing and testing of the Block 1 vehicle for the first launch of the Space Launch System (SLS). Test and flight article hardware for the liquid hydrogen fuel tank as well as the engine section for the core stage were completed at Michoud Assembly Facility (MAF) in New Orleans. Test stands neared completion at Marshall Space Flight Center for the propellant tanks, engine section, intertank and payload section. Stennis Space Center completed major structural renovations on the B2 test stand, where the core stage "green run" test program will be conducted. The SLS team completed a hotfire test series at Stennis to successfully demonstrate the ability of the RS-25 engine to operate under SLS environments and performance conditions. The team also test fired the second qualification five-segment solid rocket motor and cast the first six motor segments for the first SLS mission. The Interim Cryogenic Propulsion Stage (ICPS) test article was delivered to Marshall for structural tests, and work is nearly finished on the flight stage. Flight software testing completed at Marshall included power quality and command and data handling. In 2017, that work continues. SLS completed Preliminary Design Review (PDR) on the Exploration Upper Stage (EUS), a powerful, human-rated spacecraft that will propel explorers to cis-lunar space. In 2017, hardware will continue to be integrated at MAF for core stage structural test articles and the first two operational flights. RS-25 hotfire testing will continue to explore engine performance, as well as test flight-like software and four new Engine Controller Units (ECUs) for the first mission. Production of development components for a more affordable RS-25 design is underway. Core stage structural test articles have begun arriving at Marshall. While engineering challenges typical of a new development are possible, SLS is working toward launch readiness in late 2018. This paper will discuss these and other technical and programmatic successes and challenges over the past year and provide a preview of work ahead before first flight

Cook, Jerry↗
NASA NTRS1981

SEPAC software configuration control plan and procedures, revision 1

SEPAC Software Configuration Control Plan and Procedures are presented. The objective of the software configuration control is to establish the process for maintaining configuration control of the SEPAC software beginning with the baselining of SEPAC Flight Software Version 1 and encompass the integration and verification tests through Spacelab Level IV Integration. They are designed to provide a simplified but complete configuration control process. The intent is to require a minimum amount of paperwork but provide total traceability of SEPAC software.

Source record↗
NASA NTRS1984

Functional evaluation of the Galileo attitude and articulation control subsystem using FUNSIM

The functional performance of the Galileo spacecraft's attitude and articulation control subsystem is evaluated. The tests are performed utilizing the simulation program developed on an IBM 370 system known as the Functional Simulation (FUNSIM). FUNSIM is an entirely software-based simulation which uses the actual flight software in HAL/S and simulated spacecraft dynamics in FORTRAN language. A description of how the test cases were selected to verify that the algorithms perform functionally correctly, and a summary of the problems encountered are included in the paper. The benefits of having an alternative test bed such as FUNSIM to the real-time simulation test beds which utilize the spacecraft hardware components in discovering the problems are described. A sample test case which shows that the desired tasks were performed functionally correctly is included in the paper. The commands in this test are selected to start the dual-spin spacecraft initially in launch mode and lead it all the way to inertial mode. Major attitude control algorithms such as rotor and platform attitude estimators, clock and core platform attitude estimators, clock and core platform controllers, and the command turn and burn are examined.

Namiri, M. K.↗
NASA NTRS2003

Use of Soft Computing Technologies For Rocket Engine Control

The problem to be addressed in this paper is to explore how the use of Soft Computing Technologies (SCT) could be employed to further improve overall engine system reliability and performance. Specifically, this will be presented by enhancing rocket engine control and engine health management (EHM) using SCT coupled with conventional control technologies, and sound software engineering practices used in Marshall s Flight Software Group. The principle goals are to improve software management, software development time and maintenance, processor execution, fault tolerance and mitigation, and nonlinear control in power level transitions. The intent is not to discuss any shortcomings of existing engine control and EHM methodologies, but to provide alternative design choices for control, EHM, implementation, performance, and sustaining engineering. The approaches outlined in this paper will require knowledge in the fields of rocket engine propulsion, software engineering for embedded systems, and soft computing technologies (i.e., neural networks, fuzzy logic, and Bayesian belief networks), much of which is presented in this paper. The first targeted demonstration rocket engine platform is the MC-1 (formerly FASTRAC Engine) which is simulated with hardware and software in the Marshall Avionics & Software Testbed laboratory that

Trevino, Luis C.↗
NASA NTRS2006

Achieving Operability via the Mission System Paradigm

In the past, flight and ground systems have been developed largely-independently, with the flight system taking the lead, and dominating the development process. Operability issues have been addressed poorly in planning, requirements, design, I&T, and system-contracting activities. In many cases, as documented in lessons-learned, this has resulted in significant avoidable increases in cost and risk. With complex missions and systems, operability is being recognized as an important end-to-end design issue. Never-the-less, lessons-learned and operability concepts remain, in many cases, poorly understood and sporadically applied. A key to effective application of operability concepts is adopting a 'mission system' paradigm. In this paradigm, flight and ground systems are treated, from an engineering and management perspective, as inter-related elements of a larger mission system. The mission system consists of flight hardware, flight software, telecom services, ground data system, testbeds, flight teams, science teams, flight operations processes, procedures, and facilities. The system is designed in functional layers, which span flight and ground. It is designed in response to project-level requirements, mission design and an operations concept, and is developed incrementally, with early and frequent integration of flight and ground components.

ground systems↗
NASA NTRS2015

Flight Testing of Guidance, Navigation and Control Systems on the Mighty Eagle Robotic Lander Testbed

During 2011 a series of progressively more challenging flight tests of the Mighty Eagle autonomous terrestrial lander testbed were conducted primarily to validate the GNC system for a proposed lunar lander. With the successful completion of this GNC validation objective the opportunity existed to utilize the Mighty Eagle as a flying testbed for a variety of technologies. In 2012 an Autonomous Rendezvous and Capture (AR&C) algorithm was implemented in flight software and demonstrated in a series of flight tests. In 2012 a hazard avoidance system was developed and flight tested on the Mighty Eagle. Additionally, GNC algorithms from Moon Express and a MEMs IMU were tested in 2012. All of the testing described herein was above and beyond the original charter for the Mighty Eagle. In addition to being an excellent testbed for a wide variety of systems the Mighty Eagle also provided a great learning opportunity for many engineers and technicians to work a flight program.

Hannan, Mike↗
NASA NTRS2017

Colloid Microthruster Flight Performance Results from Space Technology 7 Disturbance Reduction System

Space Technology 7 Disturbance Reduction System (ST7-DRS) is a NASA technology demonstration payload as part of the ESA LISA Pathfinder (LPF) mission, which launched on December 3, 2015. The ST7-DRS payload includes colloid microthrusters as part of a drag-free dynamic control system (DCS) hosted on an integrated avionics unit (IAU) with spacecraft attitude and test mass position provided by the LPF spacecraft computer and the highly sensitive gravitational reference sensor (GRS) as part of the LISA Technology Package (LTP). The objective of the DRS was to validate two technologies: colloid micro-Newton thrusters (CMNT) to provide low-noise control capability of the spacecraft, and drag-free flight control. The CMNT were developed by Busek Co., Inc., in a partnership with NASA Jet Propulsion Laboratory (JPL), and the DCS algorithms and flight software were developed at NASA Goddard Space Flight Center (GSFC). ST7-DRS demonstrated drag-free operation with 10nmHz level precision spacecraft position control along the primary axis of the LTP using eight CMNTs that provided 5-30 N each with 0.1 N precision. The DCS and CMNTs performed as required and as expected from ground test results, meeting all Level 1 requirements based on on-orbit data and analysis. DRS microthrusters operated for 2400 hours in flight during commissioning activities, a 90-day experiment and the extended mission. This mission represents the first validated demonstration of electrospray thrusters in space, providing precision spacecraft control and drag-free operation in a flight environment with applications to future gravitational wave observatories like LISA.

Ziemer, John↗
NASA NTRS1996

An Integrated Approach To Payload System Simulation

This paper describes a payload system simulation implemented at JPL as part of a comprehensive mission simulation facility. The flight software function includes communication with other process modules, instrument control, and data management. The payload system simulation software consists of: a camera subsystem, a virtual world, and a mission visualization toolset.

dynamics model photometric model geological model ↗
NASA NTRS1981

An evaluation of the Interactive Software Invocation System (ISIS) for software development applications

The Interactive Software Invocation System (ISIS), which allows a user to build, modify, control, and process a total flight software system without direct communications with the host computer, is described. This interactive data management system provides the user with a file manager, text editor, a tool invoker, and an Interactive Programming Language (IPL). The basic file design of ISIS is a five level hierarchical structure. The file manager controls this hierarchical file structure and permits the user to create, to save, to access, and to purge pages of information. The text editor is used to manipulate pages of text to be modified and the tool invoker allows the user to communicate with the host computer through a RUN file created by the user. The IPL is based on PASCAL and contains most of the statements found in a high-level programming language. In order to evaluate the effectiveness of the system as applied to a flight project, the collection of software components required to support the Annular Suspension and Pointing System (ASPS) flight project were integrated using ISIS. The ASPS software system and its integration into ISIS is described.

Noland, M. S.↗
NASA NTRS2013

Mars Science Laboratory Frame Manager for Centralized Frame Tree Database and Target Pointing

The FM (Frame Manager) flight software module is responsible for maintaining the frame tree database containing coordinate transforms between frames. The frame tree is a proper tree structure of directed links, consisting of surface and rover subtrees. Actual frame transforms are updated by their owner. FM updates site and saved frames for the surface tree. As the rover drives to a new area, a new site frame with an incremented site index can be created. Several clients including ARM and RSM (Remote Sensing Mast) update their related rover frames that they own. Through the onboard centralized FM frame tree database, client modules can query transforms between any two frames. Important applications include target image pointing for RSM-mounted cameras and frame-referenced arm moves. The use of frame tree eliminates cumbersome, error-prone calculations of coordinate entries for commands and thus simplifies flight operations significantly.

quaternion↗
NASA NTRS1999

Landsat-7 Simulation and Testing Environments

A spacecraft Attitude Control and Determination Subsystem (ACDS) is heavily dependent upon simulation throughout its entire development, implementation and ground test cycle. Engineering simulation tools are typically developed to design and analyze control systems to validate the design and software simulation tools are required to qualify the flight software. However, the need for simulation does not end here. Operating the ACDS of a spacecraft on the ground requires the simulation of spacecraft dynamics, disturbance modeling and celestial body motion. Sensor data must also be simulated and substituted for actual sensor data on the ground so that the spacecraft will respond by sending commands to the actuators as they will on orbit. And finally, the simulators is the primary training tool and test-bed for the Flight Operations Team. In this paper various ACDS simulation, developed for or used by the Landsat 7 project will be described. The paper will include a description of each tool, its unique attributes, and its role in the overall development and testing of the ACDS. Finally, a section is included which discusses how the coordinated use of these simulation tools can maximize the probability of uncovering software, hardware and operations errors during the ground test process.

Holmes, E.↗
NASA NTRS1999

Spacecraft Onboard Software Maintenance: An Effective Approach which Reduces Costs and Increases Science Return

Flight software (FSW) is a mission critical element of spacecraft functionality and performance. When ground operations personnel interface to a spacecraft, they are dealing almost entirely with onboard software. This software, even more than ground/flight communications systems, is expected to perform perfectly at all times during all phases of on-orbit mission life. Due to the fact that FSW can be reconfigured and reprogrammed to accommodate new spacecraft conditions, the on-orbit FSW maintenance team is usually significantly responsible for the long-term success of a science mission. Failure of FSW can result in very expensive operations work-around costs and lost science opportunities. There are three basic approaches to staffing on-orbit software maintenance, namely: (1) using the original developers, (2) using mission operations personnel, or (3) assembling a Center of Excellence for multi-spacecraft on-orbit FSW support. This paper explains a National Aeronautics and Space Administration, Goddard Space Flight Center (NASA/GSFC) experience related to the roles of on-orbit FSW maintenance personnel. It identifies the advantages and disadvantages of each of the three approaches to staffing the FSW roles, and demonstrates how a cost efficient on-orbit FSW Maintenance Center of Excellence can be established and maintained with significant return on the investment.

Shell, Elaine M.↗
NASA NTRS1985

Development and implementation of the verification process for the shuttle avionics system

The background of the shuttle avionics system design and the unique drivers associated with the redundant digital multiplexed data processing system are examined. With flight software pervading to the lowest elements of the flight critical subsystems, it was necessary to identify a unique and orderly approach of verifying the system as flight ready for STS-1. The approach and implementation plan is discussed, and both technical problems and management issues are dealt with.

Smith, H. E.↗
NASA NTRS1992

Developing Software For A Flight-Control System

Improved process for development of flight-control software devised by integrating conventional software-development process with conventional control-system-analysis process. Reduces costs of development, eliminates need for reengineering, and almost eliminates production errors. Concept applicable to design of other control systems and of complicated hardware-and-software systems in general.

Murray, Jonathan↗