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At least 55 records · Page 3

Integrated Testing Approaches for the NASA Ares I Crew Launch Vehicle

The Ares I crew launch vehicle is being developed by the U.S. National Aeronautics and Space Administration (NASA) to provide crew and cargo access to the International Space Station (ISS) and, together with the Ares V cargo launch vehicle, serves as a critical component of NASA's future human exploration of the Moon. During the preliminary design phase, NASA defined and began implementing plans for integrated ground and flight testing necessary to achieve the first human launch of Ares I. The individual Ares I flight hardware elements - including the first stage five segment booster (FSB), upper stage, and J-2X upper stage engine - will undergo extensive development, qualification, and certification testing prior to flight. Key integrated system tests include the upper stage Main Propulsion Test Article (MPTA), acceptance tests of the integrated upper stage and upper stage engine assembly, a full-scale integrated vehicle ground vibration test (IVGVT), aerodynamic testing to characterize vehicle performance, and integrated testing of the avionics and software components. The Ares I-X development flight test will provide flight data to validate engineering models for aerodynamic performance, stage separation, structural dynamic performance, and control system functionality. The Ares I-Y flight test will validate ascent performance of the first stage, stage separation functionality, validate the ability of the upper stage to manage cryogenic propellants to achieve upper stage engine start conditions, and a high-altitude demonstration of the launch abort system (LAS) following stage separation. The Orion 1 flight test will be conducted as a full, un-crewed, operational flight test through the entire ascent flight profile prior to the first crewed launch.

Taylor, James L.↗

Integrated System Test Approaches for the NASA Ares I Crew Launch Vehicle

The Ares I Crew Launch Vehicle (CLV) is being developed by the U.S. National Aeronautics and Space Administration (NASA) to provide crew access to the International Space Station (ISS) and, together with the Ares V Cargo Launch Vehicle (CaLV), serves as one component of a future launch capability for human exploration of the Moon. During the system requirements definition process and early design cycles, NASA defined and began implementing plans for integrated ground and flight testing necessary to achieve the first human launch of Ares I. The individual Ares I flight hardware elements: the first stage five segment booster (FSB), upper stage, and J-2X upper stage engine, will undergo extensive development, qualification, and certification testing prior to flight. Key integrated system tests include the Main Propulsion Test Article (MPTA), acceptance tests of the integrated upper stage and upper stage engine assembly, a full-scale integrated vehicle dynamic test (IVDT), aerodynamic testing to characterize vehicle performance, and integrated testing of the avionics and software components. The Ares I-X development flight test will provide flight data to validate engineering models for aerodynamic performance, stage separation, structural dynamic performance, and control system functionality. The Ares I-Y flight test will validate ascent performance of the first stage, stage separation functionality, and a highaltitude actuation of the launch abort system (LAS) following separation. The Orion-1 flight test will be conducted as a full, un-crewed, operational flight test through the entire ascent flight profile prior to the first crewed launch.

Cockrell, Charles E., Jr.↗

Standardizing GPU Radiation Test Approaches

While some Graphical Processing Units (GPUs) are discrete components (i.e.GTX1050), others take the form of an IP block or embedded engine within a System on Chip (SoC) device such as the Qualcomm Snapdragon"TM" 820 which contains a Qualcomm Adreno"TM" 530 GPU. Within this device are various functional blocks which can be exercised with software payloads. NVidia's Jetson"TM" TX1 SoC is provided on a System on Module (SOM). Within it are Central Processing Unit (CPU) cores and an nVidia GPU which can be accessed similarly to a discrete GPU coprocessor. While the packaging is different, each one of these GPUs needs to be tested using the same standardized code.

Single Event Effects (SEE)↗

Single Event Effects (SEE) Testing: Practical Approach to Test Plans

While standards and guidelines for performing SEE testing have existed for several decades, guidance for developing SEE test plans has not been as easy to find. In this presentation, the variety of areas that need to be considered ranging from resource issues (funds, personnel, schedule) to extremely technical challenges (particle interaction and circuit application), shall be discussed. Note: we consider the approach outlined here as a "living" document: Mission-specific constraints and new technology related issues always need to be taken into account.

Single Event Effects (SEE)↗

The NASA Dryden AAR Project: A Flight Test Approach to an Aerial Refueling System

The integration of uninhabited aerial vehicles (UAVs) into controlled airspace has generated a new era of autonomous technologies and challenges. Autonomous aerial refueling would enable UAVs to travel further distances and loiter for extended periods over time-critical targets. The NASA Dryden Flight Research Center recently has completed a flight research project directed at developing a dynamic hose and drogue system model to support the development of an automated aerial refueling system. A systematic dynamic model of the hose and drogue system would include the effects of various influences on the system, such as flight condition, hose and drogue type, tanker type and weight, receiver type, and tanker and receiver maneuvering. Using two NASA F/A-18 aircraft and a conventional hose and drogue aerial refueling store from the Navy, NASA has obtained flight research data that document the response of the hose and drogue system to these effects. Preliminary results, salient trends, and important lessons are presented.

Hansen, Jennifer L.↗

The NASA Dryden Flight Test Approach to an Aerial Refueling System

The integration of uninhabited aerial vehicles (UAVs) into controlled airspace has generated a new era of autonomous technologies and challenges. Autonomous aerial refueling would enable UAVs to travel further distances and loiter for extended periods over time-critical targets. The NASA Dryden Flight Research Center recently has completed a flight research project directed at developing a dynamic hose and drogue system model to support the development of an automated aerial refueling system. A systematic dynamic model of the hose and drogue system would include the effects of various influences on the system, such as flight condition, hose and drogue type, tanker type and weight, receiver type, and tanker and receiver maneuvering. Using two NASA F/A-18 aircraft and a conventional hose and drogue aerial refueling store from the Navy, NASA has obtained flight research data that document the response of the hose and drogue system to these effects. Preliminary results, salient trends, and important lessons are presented

Hansen, Jennifer L.↗

An experimental evaluation of the effectiveness of random testing of fault-tolerant software

Results of a fault-tolerant software (FTS) experiment are used to show deficiencies of the simple random testing approach. Testing was performed using randomly generated test cases supplemented with extremal and special value (ESV) cases. Error detection efficiency of the random testing approach, with emphasis on correlated errors, was compared to the error detecting capabilities of the ESV data and found deficient. The use of carefully designed test cases as a supplement to random testing, as well as the use of structure based testing are recommended.

Vouk, Mladen A.↗

Orion Capsule Parachute Assembly System (CPAS) Riser Twist Load Amplification

Any cluster of parachute systems is subject to effects on performance due to interactions between the parachutes. One such interaction is the twisting of a riser from one parachute around that of another. Due to friction and relative motion between the risers, it is possible for the tension in the riser near the attach point to be different from the tension in the riser towards the suspension lines or canopy. This could result in system failure due to larger than expected loading. The Orion Capsule Parachute Assembly System (CPAS) designed and executed a test to quantify the amplification of the load in a parachute riser due to twist, rocking rate and angle, cluster size, and canopy load. The design of the testing approach, test matrix, and hardware are discussed along with results and findings.

Parachute↗

Preliminary Design, Testing, and Performance of the LOFTID Navigation System

The Low Earth Orbit Flight Test of an Inflatable Decelerator (LOFTID) involves the first orbital test of an inflatable decelerator. This test involves the LOFTID re-entry vehicle using an inflatable decelerator to re-enter the atmosphere after flying to orbit as a secondary payload. Due to system constraints, including spin stabilization, unknown time of day, a limited space available for antennas, and a heat shield which blocks magnetic fields, the navigation system includes only an inertial measurement unit and a single GPS receiver. As the vehicle is turned off for the first part of the mission and will not receive commands or data from the ground, the navigation system will not have accurate initialization, and will in-stead rely on pre-flight estimates or first measurement estimation. This could result in significant unknown error in the initial state, resulting in needing to initialize the state on-orbit and requires using the single GPS antenna for attitude updates. These design considerations led to using an Extended Kalman filter, modified to perform with these design constraints. A streamlined testing approach, including tests with flight-like rotations, is being used to limit the time and resources needed to test the navigation system while still fully testing the performance and robustness of the navigation system. This testing approach follows the NASA test-as-you-fly principle and allows for early detection of errors and changes that are needed in the software. This results in a navigation system that, even within the design constraints of the mission architecture, will provide the performance and robustness needed of the mission.

Joel Amert↗

Improved Test Planning and Analysis Through the Use of Advanced Statistical Methods

The goal of this work is, through computational simulations, to provide statistically-based evidence to convince the testing community that a distributed testing approach is superior to a clustered testing approach for most situations. For clustered testing, numerous, repeated test points are acquired at a limited number of test conditions. For distributed testing, only one or a few test points are requested at many different conditions. The statistical techniques of Analysis of Variance (ANOVA), Design of Experiments (DOE) and Response Surface Methods (RSM) are applied to enable distributed test planning, data analysis and test augmentation. The D-Optimal class of DOE is used to plan an optimally efficient single- and multi-factor test. The resulting simulated test data are analyzed via ANOVA and a parametric model is constructed using RSM. Finally, ANOVA can be used to plan a second round of testing to augment the existing data set with new data points. The use of these techniques is demonstrated through several illustrative examples. To date, many thousands of comparisons have been performed and the results strongly support the conclusion that the distributed testing approach outperforms the clustered testing approach.

Green, Lawrence L.↗

Initial Test Results for NASA Goddard’s Low-Cost Optical Terminal Adaptive Optics System

This presentation presents the testing approach and initial laboratory test results of the Adaptive Optics (AO) Subassembly (AOS) for the Low-Cost Optical Terminal (LCOT), a low-cost and flexible optical communications ground terminal. Leveraging commercial components and subassemblies wherever possible, LCOT is being developed by the NASA Goddard Space Flight Center (GSFC) Advanced Communications Capabilities for Exploration and Science Systems (ACCESS) project. An economical ground terminal allows NASA to create a global optical terminal network and enables the expansion of direct-to-Earth (DTE) optical communications. Located at the Goddard Geophysical and Astronomical Observatory (GGAO), LCOT is in the development phase and will receive first light during initial testing beginning in 2023. This new optical terminal includes a 700 mm Ritchey-Chretien commercial telescope, able to track Low Earth Orbit (LEO) spacecraft, receive instruments specified from 1500 - 1600 nm, and an uplink transmit optical system. Demodulation of optical coherent modulation formats requires downlink signal coupling into single-mode fiber. Due to atmospheric turbulence, signals experience wavefront distortions creating speckle patterns larger than the fiber core and high jitter requiring precise beam steering. AO is necessary to correct atmospheric turbulence effects and allow efficient coupling of received signals. In 2020, GSFC contracted with General Atomics to provide the LCOT AO system. This system has been delivered to GSFC in September 2021 and has been tested in laboratory to evaluate performance. This paper describes the laboratory testing approach, turbulence phase plate design, test results, and the AO field testing plan when installed on the LCOT telescope.

Adaptive Optics↗

Effects of joints in truss structures

The response of truss-type structures for future space applications, such as Large Deployable Reflector (LDR), will be directly affected by joint performance. Some of the objectives of research at BAC were to characterize structural joints, establish analytical approaches that incorporate joint characteristics, and experimentally establish the validity of the analytical approaches. The test approach to characterize joints for both erectable and deployable-type structures was based upon a Force State Mapping Technique. The approach pictorially shows how the nonlinear joint results can be used for equivalent linear analysis. Testing of the Space Station joints developed at LaRC (a hinged joint at 2 Hz and a clevis joint at 2 Hz) successfully revealed the nonlinear characteristics of the joints. The Space Station joints were effectively linear when loaded to plus or minus 500 pounds with a corresponding displacement of about plus or minus 0.0015 inch. It was indicated that good linear joints exist which are compatible with errected structures, but that difficulty may be encountered if nonlinear-type joints are incorporated in the structure.

Ikegami, R.↗