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All sourcesNASA NTRSDOE OSTI
NASA NTRS1988

Design guide: Designing and building high voltage power supplies, volume 2

This report contains an accumulation of publications and analyses aimed at developing guidelines for improving both high voltage and low voltage power supplies for the U.S. Air Force systems command. It is the intent of the report to supply good design and manufacturing techniques for the packaging and the building of high quality, reliable, long-life power supplies. These data are based on the wealth of engineering practices established by design and manufacturing engineers. The contents are: Fundamentals of Insulation: Gases, Liquid Dielectrics, Solid Insulation; Environment: Pressure, Particulates, Environmental Interactions with Space Power Systems, Surface Charging, System Design Criteria; Configuration and Design Data: Designs, Transients, Grounding and Bonding, Thermal Control; Materials and Processes: Insulation, Processes, Process Variables; Manufacturing: Yield, Government and Industrial Survey, Analysis, Problem Areas and Suggested Solutions, Designs That Have Worked in High Voltage Equipment, Manufacturing Summary; and Tests: Performance, Insulation Tests, Materials Testing, Component and Equipment Tests, Performance Testing, Facility and Environment, Accelerated Life Test; Maintenance and Repair: Maintenance, Test Sets, Pilots and Crewmen, Air Logistic Centers, Design Problem Recommendations.

W G Dunbar↗
NASA NTRS1993

Locating Damaged Truss Members From Responses To Vibrations

Method of on-orbit assessment for location of damage based on use of capabilities of vibration-control system to measure vibrations in structure. Experiment involved use of laboratory scale-model truss structure exhibiting expected characteristics of truss structures proposed for large spacecraft. Vibrations excited in truss, and measurements of responses of structure used in series of two identification algorithms to produce mathematical model of structure in current condition, possibly containing damage. Similar methods considered for examining buildings for damage by earthquakes.

Smith, S. W.↗
NASA NTRS1998

Structural Similitude and Scaling Laws

Aircraft and spacecraft comprise the class of aerospace structures that require efficiency and wisdom in design, sophistication and accuracy in analysis and numerous and careful experimental evaluations of components and prototype, in order to achieve the necessary system reliability, performance and safety. Preliminary and/or concept design entails the assemblage of system mission requirements, system expected performance and identification of components and their connections as well as of manufacturing and system assembly techniques. This is accomplished through experience based on previous similar designs, and through the possible use of models to simulate the entire system characteristics. Detail design is heavily dependent on information and concepts derived from the previous steps. This information identifies critical design areas which need sophisticated analyses, and design and redesign procedures to achieve the expected component performance. This step may require several independent analysis models, which, in many instances, require component testing. The last step in the design process, before going to production, is the verification of the design. This step necessitates the production of large components and prototypes in order to test component and system analytical predictions and verify strength and performance requirements under the worst loading conditions that the system is expected to encounter in service. Clearly then, full-scale testing is in many cases necessary and always very expensive. In the aircraft industry, in addition to full-scale tests, certification and safety necessitate large component static and dynamic testing. Such tests are extremely difficult, time consuming and definitely absolutely necessary. Clearly, one should not expect that prototype testing will be totally eliminated in the aircraft industry. It is hoped, though, that we can reduce full-scale testing to a minimum. Full-scale large component testing is necessary in other industries as well, Ship building, automobile and railway car construction all rely heavily on testing. Regardless of the application, a scaled-down (by a large factor) model (scale model) which closely represents the structural behavior of the full-scale system (prototype) can prove to be an extremely beneficial tool. This possible development must be based on the existence of certain structural parameters that control the behavior of a structural system when acted upon by static and/or dynamic loads. If such structural parameters exist, a scaled-down replica can be built, which will duplicate the response of the full-scale system. The two systems are then said to be structurally similar. The term, then, that best describes this similarity is structural similitude. Similarity of systems requires that the relevant system parameters be identical and these systems be governed by a unique set of characteristic equations. Thus, if a relation or equation of variables is written for a system, it is valid for all systems which are similar to it. Each variable in a model is proportional to the corresponding variable of the prototype. This ratio, which plays an essential role in predicting the relationship between the model and its prototype, is called the scale factor.

Simitses, George J.↗
NASA NTRSDate not supplied

Corridor Design and Analysis for UAM Operations

The Urban Air Mobility (UAM) concept is a part of Advanced Air Mobility (AAM), a joint initiative between the Federal Aviation Administration (FAA), NASA, and industry to develop an air transportation system that uses new electric (i.e., green) air vehicles in geographical areas previously underserved by traditional aviation. Market forecast studies predict that there will be demand for alternate modes of air transportation using electric Vertical Take-off and Landing aircraft. UAM expands transportation networks by introducing short flights to move people and goods around metropolitan areas​. UAM is expected to improve mobility for the public, decongest road traffic, reduce trip time, and decrease strain on existing public transportation networks. Various challenges exist to make the introduction of UAM operations successful in the U.S. National Airspace System (NAS). These include but are not limited to integration with existing airports and airspace, provision of air traffic services (e.g., separation), vehicle design and certification, and community acceptance. The focus of this paper is on integration of UAM operations into the NAS via introduction of new airspace structures. UAM will operate within a regulatory, operational, and technical environment that is incorporated into the NAS​. As per the UAM Concept of Operations (ConOps), the FAA retains regulatory authority and is responsible for establishing operational parameters and maintaining oversight. The FAA’s UAM ConOps describes flights at low altitudes (below 5,000 ft) with minimal disruption to established conventional aircraft traffic and limited voice interactions with the Air Traffic Control (ATC). Early stages of UAM may use existing procedures to safely integrate UAM with conventional flights. This would involve flying under Part 91 Visual Flight Rules (VFR) and using voice for communications. The initial UAM ecosystem will utilize the current infrastructure such as routes, helipads, and ATC services, where practicable. ​A NASA study explored the use of existing helicopter routes in Dallas Fort Worth (DFW) airspace for initial UAM operations with a Letter of Agreement (LOA) that included procedures to request a Class B (controlled airspace) clearance. The research showed that the chosen approach was feasible for near-term, low-demand UAM traffic, but was not scalable. The growth of operations in today’s aviation system has resulted in airspace reorganization and procedures to ensure safety and efficiency as traffic rates increase. One proposed operating innovation that can help with the scalability of UAM is establishing routes and corridors. This may look similar to the Area Navigation (RNAV) procedures used today to streamline operations into busy airports. However, instead of FAA automation systems and ATC managing the flow of traffic, some UAM concepts envision a third-party service provider performing this role as part of the Provider of Services for UAM (PSU) network. The FAA’s UAM ConOps posits that new airspace structures such as UAM corridors include the following design criteria: 1) Minimal impact on existing NAS operations, 2) no or minimal additional ATC services, 3) public interest considerations such as noise, safety, and security, and 4) customer needs. The airspace available in urban environments is limited by the height of buildings, the effect of weather including wind gusts, privacy needs, and a clearance envelope. The new airspace structure would need to be designed around large airports and urban areas where the initial market demand is likely to exist. NASA has started evaluating airspace in the Dallas Fort Worth area to design new airspace structures, keeping the first two design criteria in mind. It is assumed that there will be an on-board pilot-in-command, and the flights will operate under VFR in Visual Meteorological Conditions. Corridors will be required in controlled airspace, whereas UAM operations can fly in uncontrolled Class G and E airspace using current day rules. Keeler et. al identified factors and heuristics for development of routes for UAM operations for integration with airspace close to large airports such as Dallas Fort Worth and Dallas Love Field. This paper describes the heuristics applied to define the corridors, analyzes them with respect to legacy traffic and presents key results.

Urban Air Mobility↗
NASA NTRS1978

Reconfigurable modular computer networks for spacecraft on-board processing

The core electronics subsystems on unmanned spacecraft, which have been sent over the last 20 years to investigate the moon, Mars, Venus, and Mercury, have progressed through an evolution from simple fixed controllers and analog computers in the 1960's to general-purpose digital computers in current designs. This evolution is now moving in the direction of distributed computer networks. Current Voyager spacecraft already use three on-board computers. One is used to store commands and provide overall spacecraft management. Another is used for instrument control and telemetry collection, and the third computer is used for attitude control and scientific instrument pointing. An examination of the control logic in the instruments shows that, for many, it is cost-effective to replace the sequencing logic with a microcomputer. The Unified Data System architecture considered consists of a set of standard microcomputers connected by several redundant buses. A typical self-checking computer module will contain 23 RAMs, two microprocessors, one memory interface, three bus interfaces, and one core building block.

Rennels, D. A.↗
NASA NTRS1981

The application of soft X-ray imaging techniques to auroral research

The feasibility of building and operating a grazing incidence X-ray telescope for auroral zone studies from the Polar Plasma Laboratory (PPL) is discussed. A detailed structural analysis of the preferred design, an array of seven nested Wolter mirrors, is presented. An engineering evaluation of the requirements for the instrumental configuration, power, weight and telemetry is included. The problems of radiation hardening and thermal control are discussed. The resulting strawman instrument is presented.

Source record↗
NASA NTRS2010

NASA Education: Yesterday's Dream...Today's Vision...Tomorrow's Hope

For 50 years, NASA's journeys into air and space have developed humankind's understanding of the universe, advanced technology breakthroughs, enhanced air travel safety and security, and expanded the frontiers of scientific research. These accomplishments share a common genesis: education. Education is a fundamental element of NASA's activities, reflecting a balanced and diverse portfolio of: Elementary and Secondary Education, Higher Education, e-Education, Informal Education, and Minority University Research and Education Programs (MUREP). Previous experience has shown that implementing exciting and compelling NASA missions are critical to inspiring the next generation of explorers, innovators, and leaders. Through partnerships with the Agency's Mission Directorates, other federal agencies, private industries, scientific research, and education/academic organizations, NASA's unique mission and education initiatives (content, people, and facilities) are helping to spark student interest and to guide them toward careers in science, technology, engineering, and mathematics (STEM). NASA continues to inspire the next generation of explorers, innovators, and future leaders through its educational investments, which are designed to: (1) Strengthen NASA and the Nation's future workforce -- NASA will identify and develop the critical skills and capabilities needed to ensure achievement of exploration, science, and aeronautics. (2) Attract and retain students in STEM disciplines through a progression of educational opportunities for students, teachers, and faculty -- To compete effectively for the minds, imaginations, and career ambitions of America's young people, NASA will focus on engaging and retaining students in STEM education programs to encourage their pursuit of educational disciplines critical to NASA's future engineering, scientific, and technical missions. 3. Engage Americans in NASA's mission -- NASA will build strategic partnerships and links between formal and informal STEM education providers. Through hands-on, interactive, educational activities, NASA will engage students, educators, families, the general public, and all agency stakeholders in increasing America's science and technology literacy. NASA Education uses multiple methods to assess and evaluate the success of its programs and projects. Methods include strategic planning, management and control, expert evaluations and assessments, competitive acquisition, and analysis of performance measurement data and metrics. Additional control measures are in development. These measures will further improve data collection, assist in assessing return on investments, and provide information for accountability in project and program management. In 2009, NASA directly reached over one million students and over 115,000 educators.

Winterton, Joyce L.↗
NASA NTRS2016

Mobile Launch Platform Vehicle Assembly Area (SWMU 056) Biosparge Expansion Interim Measures Work Plan

This document presents the design details for an Interim Measure (IM) Work Plan (IMWP) for the Mobile Launch Platform/Vehicle Assembly Building (MLPV) Area, located at the John F. Kennedy Space Center (KSC), Florida. The MLPV Area has been designated Solid Waste Management Unit Number 056 (SWMU 056) under KSC's Resource Conservation and Recovery Act (RCRA) Corrective Action Program. This report was prepared by Geosyntec Consultants (Geosyntec) for the National Aeronautics and Space Administration (NASA) under contract number NNK09CA02B and NNK12CA13B, project control number ENV1642. The Advanced Data Package (ADP) presentation covering the elements of this IMWP report received KSC Remediation Team (KSCRT) approval at the December 2015 Team Meeting; the meeting minutes are included in Appendix A.

IMWP↗
NASA NTRS2018

Large Satellite Bus Reliability

NASA is proposing to build a small space station in Cis-lunar orbit called Deep Space Gateway (DSG). At the heart of the DSG is the Power and Propulsion Element (PPE) which is conceptually similar to previously designed and operated satellite buses. A satellite bus is composed of the satellite spacecraft infrastructure minus the payload, and generally includes power, propulsion, avionics, and guidance, navigation and control. In November of 2017, five companies were awarded contracts by NASA to research PPE designs. In order to better understand the reliability of large satellite buses which may be the starting point of the PPE, NASA used Weibull analysis to evaluate spacecraft with similar masses and design life to the PPE. In addition, a subset of the large satellites which had satellite buses manufactured by any one of the five companies was also evaluated. This paper provides the results of the reliability analysis and compares the reliability of the general population of large satellites to the reliability associated with large satellite buses manufactured by the five companies currently studying PPE options.

Bus↗
NASA NTRSDate not supplied

Low SWaP Onboard Satellite Navigation, Guidance, and Control Technology

Onboard autonomy is a necessity for responsive space operations. Autonomous navigation, guidance, and control (NGC) enables space missions to reduce their dependence on high demand ground assets and costly ground personnel. It also allows for in-situ decision making and higher return on mission data. A flight software and hardware system providing this capability, called “autoNGC,” is currently being developed at NASA Goddard Space Flight Center for infusion into multiple future missions. The first build of autoNGC, providing autonomous navigation for lunar orbiting spacecraft, is targeted for completion by Fall 2024. It provides sensor fusion of multiple measurement types including pseudo-range from a weak signal Global Navigation Satellite Service (GNSS) receiver, 1-way and 2-way direct to Earth (DTE) range and Doppler, bearing and range from optical camera sensed images, and an accelerometer. AutoNGC is also being targeted for future missions that involve small body proximity operations, Sun Earth Libration point orbits, and distributed systems missions (DSMs) including those at outer planets. AutoNGC flight software is being built upon the plug-and-play architecture of the core Flight System (cFS) [Ref. 1]. Figure (Slide 7) shows the message-based software bus layout of various software applications (“apps”) consisting of the standard cFS apps and autoNGC interface apps and libraries. Accurate onboard navigation and timing is obtained through the Goddard Enhanced Onboard Navigation System (GEONS) software library [Ref. 2], which fuses different measurement types through an extended Kalman filter (EKF) framework. Optical measurements that are ingested in GEONS are provided by the cFS Goddard Image Analysis and Navigation Tool (cGIANT) app [Ref. 3]. This app processes optical images to extract the bearing angles of the centroid of the imaged body (near or far), the range to the imaged body, and/or of the features on the surface of a body to perform terrain relative navigation (TRN). Measurement of range to the body’s center of mass can also be derived from the detection of the limb. The first build of autoNGC for a lunar orbiting spacecraft is a minimal size, weight, and power (SWaP) hardware design allowing for inclusion into CubeSats and SmallSat-size class buses. Advancements in miniaturized space processors, such as the SpaceCube 3.0 Mini and the SpaceCube Mini-Z [Ref. 4] are utilized for low SWaP while maintaining a high level of performance. Figure (Slide 11) shows the composition of the first autoNGC build. The current enclosure design has dimensions 12 cm x 17 cm x 13.5 cm. The box mass is expected to be less than 2 kg, and the nominal power is 21 W. The hardware interfaces are designed for flexibility with a variety of sensor inputs. The achievable navigation performance depends on the sensors utilized, including the onboard clock for 1-way pseudo-range measurements. Analysis using a configuration that consists of weak signal GPS, TRN, and 1-way DTE has shown position and velocity accuracies of 10 meters and 2 cm/s (3-σ ) RSS, respectively, with onboard time knowledge estimated to better than 13 ns (3-σ ), for a spacecraft in a representative 12-hour eccentric lunar orbit. Other measurement types such as x-rays from known pulsars (called XNAV) and cross-links can also be processed in GEONS. With the plug-and-play architecture of autoNGC, cFS apps can easily be added and replaced, even after launch. Goddard is actively seeking partners to collaborate in the development of additional capabilities for autoNGC, including industry, academia, and others across the US Government. Plans are being formulated to make the autoNGC software platform available for use by any US government organization to leverage the non-recurring engineering associated with the development of onboard autonomous NGC 3 capabilities. As advancements in space qualified sensors, microprocessors, and algorithms are made, the autoNGC platform provides a ready starting point for inclusion of these technologies.

C. J. Gramling↗
NASA NTRS2010

Operational Lessons Learned from the Ares I-X Flight Test

The Ares I-X flight test, launched in 2009, is the first test of the Ares I crew launch vehicle. This development flight test evaluated the flight dynamics, roll control, and separation events, but also provided early insights into logistical, stacking, launch, and recovery operations for Ares I. Operational lessons will be especially important for NASA as the agency makes the transition from the Space Shuttle to the Constellation Program, which is designed to be less labor-intensive. The mission team itself comprised only 700 individuals over the life of the project compared to the thousands involved in Shuttle and Apollo missions; while missions to and beyond low-Earth orbit obviously will require additional personnel, this lean approach will serve as a model for future Constellation missions. To prepare for Ares I-X, vehicle stacking and launch infrastructure had to be modified at Kennedy Space Center's Vehicle Assembly Building (VAB) as well as Launch Complex (LC) 39B. In the VAB, several platforms and other structures designed for the Shuttle s configuration had to be removed to accommodate the in-line, much taller Ares I-X. Vehicle preparation activities resulted in delays, but also in lessons learned for ground operations personnel, including hardware deliveries, cable routing, transferred work and custodial paperwork. Ares I-X also proved to be a resource challenge, as individuals and ground service equipment (GSE) supporting the mission also were required for Shuttle or Atlas V operations at LC 40/41 at Cape Canaveral Air Force Station. At LC 39B, several Shuttle-specific access arms were removed and others were added to accommodate the in-line Ares vehicle. Ground command, control, and communication (GC3) hardware was incorporated into the Mobile Launcher Platform (MLP). The lightning protection system at LC 39B was replaced by a trio of 600-foot-tall towers connected by a catenary wire to account for the much greater height of the vehicle. Like Shuttle, Ares I-X will be stacked on a MLP and rolled out to the pad on a Saturn-era crawler-transporter. While Ares I-X was only held in place by the four hold-down posts on its aft skirt during rollout, a new vehicle stabilization system (VSS) attached to the vertical service structure kept the vehicle from undue swaying prior to launch at the pad, LC 39B. Following the launch, the flight test vehicle first stage was recovered with the aid of new parachutes resized to accommodate the five-segment-long first stage, which had a much greater length and mass than the Shuttle s reusable solid rocket boosters. After splashdown, recovery divers exercised extra care when handling the first stage to ensure that the flight data recorders in the fifth segment simulator were not damaged by exposure to sea water. The data recovered from the Ares I-X flight test will be very valuable in verifying the predicted environments and models used to design the vehicle. Lessons learned from Ares I-X will be shared with the Ares Projects through written and verbal reports and through integration of mission team members into the Project workforce.

Davis, Stephan R.↗
NASA NTRS1983

Payload/cargo processing at the launch site

Payload processing at Kennedy Space Center is described, with emphasis on payload contamination control. Support requirements are established after documentation of the payload. The processing facilities feature enclosed, environmentally controlled conditions, with account taken of the weather conditions, door openings, accessing the payload, industrial activities, and energy conservation. Apparatus are also available for purges after Orbiter landing. The payloads are divided into horizontal, vertical, mixed, and life sciences and Getaway Special categories, which determines the processing route through the facilities. A canister/transport system features sealed containers for moving payloads from one facility building to another. All payloads are exposed to complete Orbiter bay interface checkouts in a simulator before actually being mounted in the bay.

Ragusa, J. M.↗
NASA NTRS1990

Lunar astronomical observatories - Design studies

The best location in the inner solar system for the grand observatories of the 21st century may be the moon. A multidisciplinary team including university students and faculty in engineering, astronomy, physics, and geology, and engineers from industry is investigating the moon as a site for astronomical observatories and is doing conceptual and preliminary designs for these future observatories. Studies encompass lunar facilities for radio astronomy and astronomy at optical, ultraviolet, and infrared wavelengths of the electromagnetic spectrum. Although there are significant engineering challenges in design and construction on the moon, the rewards for astronomy can be great, such as detection and study of earth-like planets orbiting nearby stars, and the task for engineers promises to stimulate advances in analysis and design, materials and structures, automation and robotics, foundations, and controls. Fabricating structures in the reduced-gravity environment of the moon will be easier than in the zero-gravity environment of earth orbit, as Apollo and space-shuttle missions have revealed. Construction of observatories on the moon can be adapted from techniques developed on the earth, with the advantage that the moon's weaker gravitational pull makes it possible to build larger devices than are practical on earth.

Johnson, Stewart W.↗
NASA NTRS1989

Preliminary design of a lunar construction utility vehicle

Construction of a lunar base, prior to manned occupancy, is one of the most demanding technological challenges facing space system designers today. A flexible lunar construction machine is needed that can be operated remotely and that can perform a variety of construction tasks over a wide range of lunar conditions. A preliminary lunar construction utility vehicle (LCUV) design has been developed as part of a capstone design course at Old Dominion University and is described in this summary report. The design requirements are taken from a 1988 USRA Summer Design Report entitled The Lunar Split Mission: A Robotic Constructed Lunar Base Scenario, and from the proceedings of a workshop hosted by United Technologies Corporation entitled Report of the In Situ Resources Utilization Workshop. The first report describes a bootstrap base concept in which a minimum of essential surface elements are delivered and configured such that minimum EVA is required to bring the initial base on-line. The base is to be built in three phases, the first of which will be unmanned, while the second and third will be manned. The key to these concepts is the development of a semiautonomous, telerobotic lunar construction utility vehicle (LCUV). The tasks required of this robotic vehicle during the phase 1 build-up are as follows: (1) surface element transportation, handling, and assembly; (2) soil excavation and movement for site preparation; (3) radiation protection and materials processing; and (4) repair and maintenance of surface elements. In order to meet the stated requirements, the LCUV must be: (1) transformable to perform a wide variety of tasks; (2) self supporting; (3) designed to allow for telerobotic control as well as autonomous operation; (4) able to transport one fully configured space station common module (SSCM); (5) upgradable to allow for future growth; and (6) easy to maintain.

Bryant, C. A.↗
NASA NTRS2011

Shuttle Program Loads Integration: Going From Concept to Operations and Staying Successful

From the beginning of the Shuttle Program to its end, integrated loads and dynamics analyses and tests have been critical in shaping the vehicle design and operational decisions for NASA and its customers. Starting with scaled models and simple mathematical simulations of the structural dynamics, engineers defined the required structural stiffness and predicted the limit loads for each element of the system. Early structural tests provided reasonable confidence that the models and predictions were good. The first launch of the Space Shuttle brought surprises, though, when the ignition overpressure event caused a forward fuel tank support strut to buckle, among several unexpected effects. The launch pad and other ground equipment became an integral part of the system integration, especially where the acoustic and pressure environments of ignition and lift-off were concerned. Following the Challenger accident, operating limits were changed in response to new understandings of how the integrated system performed. Controlling loads while maximizing performance was a key tenet of the Performance Enhancement design process, which enabled construction of the International Space Station. During the return to flight after the Columbia accident, engineers grew to understand that loads during the roll maneuver were also important to the vehicle s structural margin and life. At this point the crawler transport from the Vehicle Assembly Building to the launch pad also became a part of the integrated loads analysis. Even in the last years of the Space Shuttle Program, new data still provided interesting insights into this complicated and fascinating spaceship. This paper will present some examples of the important findings by the team of specialists that supported the Integrated Loads and Dynamics Panel for the Space Shuttle Program.

Bernstein, Karen↗
NASA NTRS2015

Earth Science Data Fusion with Event Building Approach

Objectives of the NASA Information And Data System (NAIADS) project are to develop a prototype of a conceptually new middleware framework to modernize and significantly improve efficiency of the Earth Science data fusion, big data processing and analytics. The key components of the NAIADS include: Service Oriented Architecture (SOA) multi-lingual framework, multi-sensor coincident data Predictor, fast into-memory data Staging, multi-sensor data-Event Builder, complete data-Event streaming (a work flow with minimized IO), on-line data processing control and analytics services. The NAIADS project is leveraging CLARA framework, developed in Jefferson Lab, and integrated with the ZeroMQ messaging library. The science services are prototyped and incorporated into the system. Merging the SCIAMACHY Level-1 observations and MODIS/Terra Level-2 (Clouds and Aerosols) data products, and ECMWF re- analysis will be used for NAIADS demonstration and performance tests in compute Cloud and Cluster environments.

Lukashin, C.↗
NASA NTRSDate not supplied

Spacecraft Line-Of-Sight Jitter Mitigation and Management Lessons Learned and Engineering Best Practices

Predicting, managing, controlling, and testing spacecraft line-of-sight (LoS) jitter caused by micro-vibrations due to onboard internal disturbance sources is a formidable multidisciplinary engineering task. It is especially challenging for those missions hosting high-performance, vibration-sensitive optical sensor payloads with stringent pointing stability requirements. Both NASA and ESA are planning technically aggressive spaceflight missions that include ultra-high-performance optical payloads with delicate, highly vibration-sensitive scientific and observational instruments. The GN&C community of practice will need to leverage and build upon their collective experiences and lessons learned to better address future micro-vibration challenges. To identify lessons learned and best engineering practices the NASA Engineering & Safety Center (NESC) sponsored a two-day Spacecraft LoS Jitter Workshop in late 2019. The workshop’s goal was to provide a multidisciplinary forum to elicit deeper understanding of the issues related to solving the spacecraft LoS jitter/micro-vibration problem. A primary objective was to identify and share best practices, rules of thumb, and options for jitter-related activities. Representatives from NASA, JPL, ESA, along with NASA’s industrial partners, independent consultant subject matter experts, and members of academia participated in the workshop. This paper will describe the motivation for the NASA Spacecraft LoS Jitter Workshop and summarize the identified findings, observations, and recommendations.

Lessons Learned;↗
NASA NTRS2012

pyam: Python Implementation of YaM

pyam is a software development framework with tools for facilitating the rapid development of software in a concurrent software development environment. pyam provides solutions for development challenges associated with software reuse, managing multiple software configurations, developing software product lines, and multiple platform development and build management. pyam uses release-early, release-often development cycles to allow developers to integrate their changes incrementally into the system on a continual basis. It facilitates the creation and merging of branches to support the isolated development of immature software to avoid impacting the stability of the development effort. It uses modules and packages to organize and share software across multiple software products, and uses the concepts of link and work modules to reduce sandbox setup times even when the code-base is large. One sidebenefit is the enforcement of a strong module-level encapsulation of a module s functionality and interface. This increases design transparency, system stability, and software reuse. pyam is written in Python and is organized as a set of utilities on top of the open source SVN software version control package. All development software is organized into a collection of modules. pyam packages are defined as sub-collections of the available modules. Developers can set up private sandboxes for module/package development. All module/package development takes place on private SVN branches. High-level pyam commands support the setup, update, and release of modules and packages. Released and pre-built versions of modules are available to developers. Developers can tailor the source/link module mix for their sandboxes so that new sandboxes (even large ones) can be built up easily and quickly by pointing to pre-existing module releases. All inter-module interfaces are publicly exported via links. A minimal, but uniform, convention is used for building modules.

Myint, Steven↗