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At least 19 records

GSFC Risk Assessment Process for Inherited Items

The NASA Goddard Space Flight Center Safety and Mission Assurance Directorate is implementing an alternate process for approval of Spacecraft Inherited Items in accordance with Goddard Procedural Requirements 8730.5. A Commodity Risk Assessment Engineer is performing an Inherited Item Risk Assessment (I2RA) for the use of Spacecraft Standard Components (items generally necessary to control the spacecraft, e.g. reaction wheel assemblies) and payload flight spares or Built-to-Print items. The I2RA may take into account prior space flight performance, criticality of the component, qualification records, quality and reliability records, storage conditions, manufacturer assessments, and mission specific parameters like mission environment and duration. The I2RA provides a means to accept for the entire item materials, parts or workmanship non-conformances, that do not significantly increase risk.

Risk Assessment↗

Worst-case space radiation environments for geocentric missions

Worst-case possible annual radiation fluences of energetic charged particles in the terrestrial space environment, and the resultant depth-dose distributions in aluminum, were calculated in order to establish absolute upper limits to the radiation exposure of spacecraft in geocentric orbits. The results are a concise set of data intended to aid in the determination of the feasibility of a particular mission. The data may further serve as guidelines in the evaluation of standard spacecraft components. Calculations were performed for each significant particle species populating or visiting the magnetosphere, on the basis of volume occupied by or accessible to the respective species. Thus, magnetospheric space was divided into five distinct regions using the magnetic shell parameter L, which gives the approximate geocentric distance (in earth radii) of a field line's equatorial intersect.

Stassinopoulos, E. G.↗

BioSentinel: Enabling CubeSat-Scale Biogical Research Beyond Low Earth Orbit

The introduction of the Space Launch System will provide NASA with a new means of access to space beyond low Earth orbit (LEO), creating opportunities for scientific research in a range of spacecraft sizes. This presentation describes the preliminary design of the BioSentinel spacecraft, a CubeSat measuring 10cm x 20cm x 30cm, which has been manifested for launch on the maiden voyage of the Space Launch System in 2017. BioSentinel will provide the first direct experimental data from a biological study conducted beyond LEO in over forty years, which in turn will help to pave the way for future human exploration missions. The combination of an advanced biology payload with standard spacecraft bus components required for operation in deep space within a CubeSat form factor poses a unique challenge, and this paper will describe the early design trades under consideration. The baseline spacecraft design calls for the biology payload to occupy four cube-units of volume (denoted 4U), with all spacecraft bus components occupying the remaining 2U.

Space Biology↗

SmallSat Navigation via the Deep Space Network: Lunar Transport

Spacecraft component miniaturization, the standardized CubeSat form factor, and a corresponding increase in launch ride-share availability have led to a renewed interest in smaller, more agile spacecraft missions. Naturally, interest in SmallSat capabilities extends outside of low Earth orbit for a variety of science and technology demonstration applications. As with larger missions, near-term deep-space SmallSats will more than likely rely on telecommunications and tracking via NASA's Deep Space Network or similar facilities. Given the predicted growth in the number of deep space missions, e ective use of telecommunication resources will be more critical than ever, even with Multiple Spacecraft Per Aperture capability. In particular, SmallSat missions will likely face stricter limitations on two-way contact with the tracking stations, thus making other options like one-way data types more attractive. While all missions must eventually develop their own detailed navigation plans, a common set of references is needed to support SmallSat missions, especially in the early development phases. Our investigation provides this initial survey of expected navigation performance for standard radiometric data types, from traditional two-way Doppler and ranging capabilities to one-way equivalents, including delta-di erential one-way range. In this investigation, we examine transport within the Earth-Moon region, the rst step outward from Earth into deep space exploration.

Wood, Lincoln↗

The NASA program for standardizing silicon solar cells

The present work describes briefly the goals of the recently organized Standardized Space Power Systems Office and its program for developing low-cost, standard power system components for spacecraft. The first step is the development of standard specifications for solar cells and covers. These include: (1) physical dimensions, materials of construction, appearance and integrity of solar cell and coverglass; (2) electrical performance characteristics of solar cell and optical characteristics of coverglass; and (3) sampling, inspection, and electrical and environmental tests needed to demonstrate compliance with the above specifications.

Bifano, W.J.↗

The GSFC Flight Support System for on-orbit satellite servicing

To plan and execute a successful on-orbit satellite servicing mission, space support hardware, a serviceable spacecraft design, and flexible ground operations are required. This paper addresses space support hardware and in particular the Goddard Space Flight Center (GSFC) Satellite Servicing Project's (SSP) Flight Support System (FSS). The FSS is designed to be compatible with the Space Transportation System Orbiter and to support on-orbit servicing of Multimission Modular Spacecraft. It provides mechanical, electrical, and thermal support to the spacecraft during the servicing mission. Standardization of spacecraft design, components, and interfaces is required to make a satellite serviceable. Spacecraft ground operation capabilities must accommodate servicing mission requirements. Space support tools and equipment, such as the Power Ratchet Tool, assists the astronaut during time critical EVA operations to more efficiently perform the servicing mission.

Griffin, Thomas J.↗

Evaluation philosophy for shuttle launched payloads

Some approaches to space-shuttle payload evaluation are examined. Issues considered include subsystem replacement in low-cost modular spacecraft (LCMS), validation of spacelab payloads, the use of standard components in shuttle-era spacecraft, effects of shuttle-induced environments on payloads, and crew safety. The LCMS is described, and goals are discussed for its evaluation program. Concepts regarding how the evaluation should proceed are considered.

Heuser, R. E.↗

Enhanced element-specific modal formulations for flexible multibody dynamics

The accuracy of current flexible multibody formalisms based on assumed modes is examined in the context of standard spacecraft motions involving structural components undergoing both slow and fast overall translational and rotational motions as well as small deformations. Limitations of current techniques in treating: (1) element-specific coupling behavior of large motion and small deformation, and (2) motion-induced structural stiffness variations, are noted. The roles of nonlinear and linear elastic structural theories in accurately predicting transient large-displacement dynamic behavior of flexible multibody systems are examined in detail. Coupling effects between deformation and overall motion are carefully scrutinized in the context of assumed-mode discretization techniques. Consistently linearized beam, plate, and shell formulations involving in-plane stretch variables are proposed and shown to yield very accurate simulation results and extremely fast modal convergence for most motions involving small strains. In some particular cases, however, in which membrane stiffness dominates bending stiffness, a nonlinear strain formulation is required in order to capture proper coupling between deformation and overall motion.

Ryan, Robert R.↗

Space Shuttle payloads - An overview

A review is made of historical developments of NASA-launched payloads as a basis for projecting payload operations configured to fit the Shuttle's capabilities, and the impetus for new spacecraft and applications designs is discussed. Payloads have experienced a growth in size and weight, capacity and lifetime, and have increasingly featured more automation, microminiaturized circuitry, and data processing systems. Launches by the DoD and NASA have averaged about 20/yr. Spacecraft specifically configured for Shuttle launch have had to wait due to development schedule delays. Partial compensation has occurred by the use of the MMS, which fits into both the Delta nose cone and the Orbiter bay. The Landsat-4 and SMM are cited as examples. Successful demonstration of in-orbit servicing of satellites is required in order to attract spacecraft designers who will make full use of the Shuttle's capabilities. Finally, increased standardization of spacecraft shape, interfaces, and components is foreseeen.

Edgecombe, D. S.↗

Autonomous Navigation Using Celestial Objects

In the twenty-first century, National Aeronautics and Space Administration (NASA) Enterprises envision frequent low-cost missions to explore the solar system, observe the universe, and study our planet. Satellite autonomy is a key technology required to reduce satellite operating costs. The Guidance, Navigation, and Control Center (GNCC) at the Goddard Space Flight Center (GSFC) currently sponsors several initiatives associated with the development of advanced spacecraft systems to provide autonomous navigation and control. Autonomous navigation has the potential both to increase spacecraft navigation system performance and to reduce total mission cost. By eliminating the need for routine ground-based orbit determination and special tracking services, autonomous navigation can streamline spacecraft ground systems. Autonomous navigation products can be included in the science telemetry and forwarded directly to the scientific investigators. In addition, autonomous navigation products are available onboard to enable other autonomous capabilities, such as attitude control, maneuver planning and orbit control, and communications signal acquisition. Autonomous navigation is required to support advanced mission concepts such as satellite formation flying. GNCC has successfully developed high-accuracy autonomous navigation systems for near-Earth spacecraft using NASA's space and ground communications systems and the Global Positioning System (GPS). Recently, GNCC has expanded its autonomous navigation initiative to include satellite orbits that are beyond the regime in which use of GPS is possible. Currently, GNCC is assessing the feasibility of using standard spacecraft attitude sensors and communication components to provide autonomous navigation for missions including: libration point, gravity assist, high-Earth, and interplanetary orbits. The concept being evaluated uses a combination of star, Sun, and Earth sensor measurements along with forward-link Doppler measurements from the command link carrier to autonomously estimate the spacecraft's orbit and reference oscillator's frequency. To support autonomous attitude determination and control and maneuver planning and control, the orbit determination accuracy should be on the order of kilometers in position and centimeters per second in velocity. A less accurate solution (one hundred kilometers in position) could be used for acquisition purposes for command and science downloads. This paper provides performance results for both libration point orbiting and high Earth orbiting satellites as a function of sensor measurement accuracy, measurement types, measurement frequency, initial state errors, and dynamic modeling errors.

Folta, David↗

Payloads.

Approaches to payload definition, design, and planning adopted in the Space Shuttle Program are described. The Space Shuttle offers many new modes of operation featuring reuse of spacecraft, on-orbit checkout and maintenance, sortie experiment missions, and opportunities to trade launch weight and volume for cost savings. In order to take advantage of these new approaches and to accommodate the varying missions, new payload elements have been identified, and new low-cost design approaches are being developed to utilize standardized components and modularized subassemblies that reduce spacecraft buildup and maintenance costs. A new payload planning technique makes use of the computer to provide large-scale planning, scheduling, and costing required for various program options.

Marshall, W. R.↗

AIAA spacecraft GN&C interface standards initiative: Overview

The American Institute of Aeronautics and Astronautics (AIAA) has undertaken an important standards initiative in the area of spacecraft guidance, navigation, and control (GN&C) subsystem interfaces. The objective of this effort is to establish standards that will promote interchangeability of major GN&C components, thus enabling substantially lower spacecraft development costs. Although initiated by developers of conventional spacecraft GN&C, it is anticipated that interface standards will also be of value in reducing the development costs of micro-engineered spacecraft. The standardization targets are specifically limited to interfaces only, including information (i.e. data and signal), power, mechanical, thermal, and environmental interfaces between various GN&C components and between GN&C subsystems and other subsystems. The current emphasis is on information interfaces between various hardware elements (e.g., between star trackers and flight computers). The poster presentation will briefly describe the program, including the mechanics and schedule, and will publicize the technical products as they exist at the time of the conference. In particular, the rationale for the adoption of the AS1773 fiber-optic serial data bus and the status of data interface standards at the application layer will be presented.

Challoner, A. Dorian↗

Lipid Decontamination Procedures for Life Detection Missions

Molecular biosignatures are key targets for current, proposed, and future life detection missions. With the high accuracy and low limit of detection (LOD) that new and future instruments will require, decontamination of life detection hardware is necessary to prevent false positives. Lipids are a molecular biosignature of interest, as they are ubiquitous to all life as we know it, can survive unaltered in the geologic record for longer than any other biomolecule (i.e. billions of years), and form through both biotic and abiotic processes. Lipids display origin-diagnostic molecular patterns that can reveal biotic or abiotic synthesis, so finding them and ascertaining their molecular features is important for potentially detecting evidence of life elsewhere. Traditional methods of decontamination, or contamination control (CC), primarily clean hardware through fabrication in sterile (cleanroom) environments, killing microbes, and removing/flushing contaminants off instrument and spacecraft components. However, research suggests that some standard cleaning methods are either unlikely to remove lipid contaminants or are incompatible with life detection instrument materials. To solve this problem, I propose to find, test, and verify a decontamination method that thoroughly cleans instruments by destroying lipid molecules, but is simultaneously compatible with major materials used in these instruments. I will study the effects of traditional CC methods (including Dry Heat Microbial Reduction and Vapor phase Hydrogen Peroxide) and experimental CC methods (Electron Beam Irradiation) on lipid molecules for application to life detection instrumentation. I will then develop a CC plan for a novel lipid detector (ExCALiBR, Extractor for Chemical Analysis of Lipid Biomarkers in Regolith) searching for lipids in either soil or icy world scenarios. This plan will uphold planetary protection regulation requirements and validate experimental analyses of in-situ life detection tests.

Decontamination↗

Power Actuation and Switching Module Test Results

The X2000 Power System Electronics (PSE) is a Jet Propulsion Laboratory (JPL) task to develop a new generation of power system building blocks for use on future deep-space missions. The effort includes the development of electronic components and modules that can be used as building blocks in the design of generic spacecraft power systems. All X2000 avionics components and modules are designed for use in centralized or distributed spacecraft architectures. The Power Actuation and Switching Module (PASM) has been developed under the X2000 program. This component enables a modular and scalable design approach for power switching applications, which can result in a wide variety of power switching architectures using this simple building block. The PASM is designed to provide most of the necessary power switching functions of spacecraft for various Deep Space missions including future missions to Mars, comets, Jupiter and its moons. It is fabricated using an ASIC process that is tolerant of high radiation. The development included two application specific integrated circuits (ASICs) and support circuitry all packaged using High Density Interconnect (HDI) technology. It can be operated in series or parallel with other PASMs. It can be used as a high-side or low-side switch and it can drive thruster valves, pyrotechnic devices such as NASA standard initiators, bus shunt resistors, and regular spacecraft component loads. Each PASM contains two independent switches with internal current limiting and over-current trip-off functions to protect the power subsystem from load faults. During turnon and turnoff each switch can limit the rate of current change (di/dt) to a value determined by the user. Three-way majority-voted On/Off commandability and full switch status telemetry (both analog and digital) are built into the module. This paper is a follow up to the one presented at he IECEC 2004 conference that will include the lessons learned and test results from the development.

X2000↗

Power Actuation and Switching Module Development

The Deep Space Avionics (DSA) Project is developing a Power Actuation and Switching Module (PASM). This component enables a modular and scalable design approach for power switching applications, which can result in a wide variety of power switching architectures using this simple building block. The PASM is designed to provide most of the necessary power switching functions of spacecraft for various Deep Space missions including future missions to Mars, comets, Jupiter and its moons. It is fabricated using an A SIC process that is tolerant of high radiation. The development includes two application specific integrated circuits (ASICs) and support circuitry all packaged using High Density Interconnect (HDI) technology. It can be operated in series or parallel with other PASMs, It can be used as a high-side or low-side switch and it can drive thruster valves, pyrotechnic devices such as NASA standard initiators, bus shunt resistors, and regular spacecraft component loads. Each PASM contains two independent switches with internal current limiting and over-current trip-off functions to protect the power subsystem from load faults. During turnon and turnoff each switch can limit the rate of current change (di/dt) to a value determined by the user. Threeway majority-voted On/Off commandability and full switch status telemetry (both analog and digital) are built into the module. This paper describes the development process used to design, model, fabricate, and test these compact and versatile power switches. Preliminary test results from prototype HDI PASM hardware are also discussed.

Power Actuation and Switching Module (PASM)↗

GSMS and space views: Advanced spacecraft monitoring tools

The Graphical Spacecraft Monitoring System (GSMS) processes and translates real-time telemetry data from the Gamma Ray Observatory (GRO) spacecraft into high resolution 2-D and 3-D color displays showing the spacecraft's position relative to the Sun, Earth, Moon, and stars, its predicted orbit path, its attitude, instrument field of views, and other items of interest to the GRO Flight Operations Team (FOT). The GSMS development project is described and the approach being undertaken for implementing Space Views, the next version of GSMS, is presented. Space Views is an object-oriented graphical spacecraft monitoring system that will become a standard component of Goddard Space Flight Center's Transportable Payload Operations Control Center (TPOCC).

Carlton, Douglas↗

NASA standard Multimission Modular Spacecraft for future space exploration

The design of the Multimission Modular Spacecraft (MMS) has evolved over the past seven years. The main objective concerning the design of the MMS has been related to aspects of cost effectiveness. Maximum use was to be made of NASA standard components. The basic concept has been to design a core spacecraft which has inherent flexibility to meet a range of mission needs without modification of its hardware elements. An overview is provided of the MMS performance capability and the current status of the MMS program. The MMS is the first NASA approved active control free-flying spacecraft to be designed to be Shuttle compatible. The design of the MMS is such that no single failure will preclude its retrieval by the Shuttle.

Bartlett, R. O.↗