Voyager capsule, preliminary design, phase B. Volume I - Summary Final report
Integrated test plan and implementation plan highlights for Voyager capsule - preliminary design phase B
SYSTEMS DESIGN↗
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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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Knowledge acquisition and rapid protyping of an expert system: Dealing with real world problems
The knowledge engineering and rapid prototyping phases of an expert system that does fault handling for a Solid Amine, Water Desorbed CO2 removal assembly for the Environmental Control and Life Support System for space based platforms are addressed. The knowledge acquisition phase for this project was interesting because it could not follow the textbook examples. As a result of this, a variety of methods were used during the knowledge acquisition task. The use of rapid prototyping and the need for a flexible prototype suggested certain types of knowledge representation. By combining various techniques, a representative subset of faults and a method for handling those faults was achieved. The experiences should prove useful for developing future fault handling expert systems under similar constraints.
Bailey, Patrick A.↗
Human Exploration Initiative
The planning and development of elements of the Human Exploration Initiative (HEI) program are described including mission designs, launch vehicles, and program phasing. Attention is given to the objective of the lunar and Martian projects as well as to the phased exploration strategy involving the Space Station Freedom, the lunar surface, and ultimately permanently manned bases on the moon and Mars. Mission profiles are illustrated for piloted and cargo missions, and the development of earth-to-orbit launch vehicles is reviewed emphasizing the uses of the Shuttle-C and the heavy-lift launch vehicle. Launch-site operations flow concepts are described for the lunar and lunar/Mars phases, and the baseline ground-processing scenarios are shown to define the preliminary facility requirements. The overview demonstrates the areas of development required for achieving the goals of the HEI program.
Goldsby, William D.↗
An Investigation of Multipath Effects on the GPS System During Auto-Rendezvous and Capture
The proposed use of a Cargo Transport Vehicle (CTV) to carry hardware to the Space Station Freedom (SSF) during the construction phase of the SSF project requires remote maneuvering of the CTV. The CTV is not a manned vehicle. Obtaining the relative positions of the CTV and SSF for remote auto-rendezvous and capture (AR&C) scenarios will rely heavily on the Global Positioning System (GPS). The GPS system is expected to guide the CTV up to a distance of 100 to 300 meters from the SSF. At some point within this range, an optical docking system will take over the remote guidance for capture. During any remote guidance by GPS it is possible that significant multipath signals may be caused by large objects in the vicinity of the module being remotely guided. This could alter the position obtained by the GPS system from the actual position. Due to the nature of the GPS signals, it has been estimated that if the difference in distance between the Line of Sight (LOS) path and the multipath is greater than 300 meters, the GPS system is capable of discriminating between the direct signal and the reflected (or multipath) signal. However, if the path difference is less than 300 meters, one must be concerned. This report details the work accomplished by the Electromagnetic Simulations Laboratory at Marquette University over the period December 1993 to May 1995. This work is an investigation of the strength and phase of a multipath signal arriving at the CTV relative to the direct or line of sight (LOS) signal. The signal originates at a GPS satellite in half geo-stationary orbit and takes two paths to the CTV: (1) the direct or LOS path from the GPS satellite to the CTV; and (2) a scattered path from the GPS satellite to the SSF module and then to the CTV. The scattering from a cylinder has been computed using the physical optics approximation for the current. No other approximations or assumptions have been made including no assumptions regarding the far field or Fresnel field approximations. The integrations required to obtain the scattered field have been computed numerically using an N dimensional Romberg integration. The total scattered electric field is then projected onto the RCP component in the direction of propagation only. The direct or line of sight signal is then used to compute the relative strength and phase of the scattered field. The trajectory of the CTV has been parameterized into 4,214 points that are calculated for each of the geometries investigated. The motion of the CTV between points is small enough for the magnitude data (dB down from direct signal) to appear very smooth; however, because of the distances and wavelengths involved, the phase of the scattered field relative to the direct signal varies very rapidly.
Richie, James E.↗
Taking the Evolutionary Road to Developing an In-House Cost Estimate
This slide presentation reviews the process and some of the problems and challenges of developing an In-House Cost Estimate (IHCE). Using as an example the Space Network Ground Segment Sustainment (SGSS) project, the presentation reviews the phases for developing a Cost estimate within the project to estimate government and contractor project costs to support a budget request.
Jacintho, David↗
The Impact of High-Dimensional Phase Space Correlations on the Beam Dynamics in a Linear Accelerator
Hadron beams develop intensity-dependent transverse-longitudinal correlations within radio-frequency quadrupole (RFQ) accelerating structures. These correlations are only visible in six-dimensional phase space and are destroyed by reconstructions from low-dimensional projections. In this work, we estimate the effect of artificial decorrelation on the beam dynamics in the Spallation Neutron Source (SNS) linac and Beam Test Facility (BTF). We show that the evolution of a realistic initial distribution and its decorrelated twin converge during the early acceleration stages; thus, low-dimensional projections are probably sufficient for detailed predictions in high-power linacs.
Hoover, Austin↗
Reduced Complexity Model Intercomparison Project Phase 1: introduction and evaluation of global-mean temperature response
Reduced-complexity climate models (RCMs) are critical in the policy and decision making space, and are directly used within multiple Intergovernmental Panel on Climate Change (IPCC) reports to complement the results of more comprehensive Earth system models. To date, evaluation of RCMs has been limited to a few independent studies. Here we introduce a systematic evaluation of RCMs in the form of the Reduced Complexity Model Intercomparison Project (RCMIP). We expect RCMIP will extend over multiple phases, with Phase 1 being the first. In Phase 1, we focus on the RCMs' global-mean temperature responses, comparing them to observations, exploring the extent to which they emulate more complex models and considering how the relationship between temperature and cumulative emissions of CO2 varies across the RCMs. Our work uses experiments which mirror those found in the Coupled Model Intercomparison Project (CMIP), which focuses on complex Earth system and atmosphere–ocean general circulation models. Using both scenario-based and idealised experiments, we examine RCMs' global-mean temperature response under a range of forcings. We find that the RCMs can all reproduce the approximately 1°C of warming since pre-industrial times, with varying representations of natural variability, volcanic eruptions and aerosols. We also find that RCMs can emulate the global-mean temperature response of CMIP models to within a root-mean-square error of 0.2°C over a range of experiments. Furthermore, we find that, for the Representative Concentration Pathway (RCP) and Shared Socioeconomic Pathway (SSP)-based scenario pairs that share the same IPCC Fifth Assessment Report (AR5)-consistent stratospheric-adjusted radiative forcing, the RCMs indicate higher effective radiative forcings for the SSP-based scenarios and correspondingly higher temperatures when run with the same climate settings. In our idealised setup of RCMs with a climate sensitivity of 3°C, the difference for the ssp585–rcp85 pair by 2100 is around 0.23°C(±0.12°C) due to a difference in effective radiative forcings between the two scenarios. Phase 1 demonstrates the utility of RCMIP's open-source infrastructure, paving the way for further phases of RCMIP to build on the research presented here and deepen our understanding of RCMs.
54 ENVIRONMENTAL SCIENCES↗
What is a system? NASA's phased project description
NASA phase A and B projects are addressed. The Phase A study is the preliminary analysis of a space concept. These concepts could have come from a pre-Phase A study or from other sources within or external to NASA. The majority of concepts that are studied at MSFC are assigned by NASA Headquarters and funded accordingly. The overall program schedule depicts important milestones that establish the start and finish dates of each study phase, including design, development, launch, and operations. The Phase B of the project consists of the refinement of preliminary requirements, cost estimates, schedules and risk assessments prior to starting final design and development. The goal of a concept definition activity is to determine the best and most feasible concept(s) that will satisfy the mission and science requirements.
Source record↗
Nuclear shuttle system definition study. Volume 7 - RNS project requirements, phase 3 Final report
Working data from functional analysis and operations analysis of reusable nuclear stage space shuttle system
Source record↗
Practical Application of PRA as an Integrated Design Tool for Space Systems
This paper presents the application of the first comprehensive Probabilistic Risk Assessment (PRA) during the design phase of a joint NASA/NOAA weather satellite program, Geostationary Operational Environmental Satellite Series R (GOES-R). GOES-R is the next generation weather satellite primarily to help understand the weather and help save human lives. PRA has been used at NASA for Human Space Flight for many years. PRA was initially adopted and implemented in the operational phase of manned space flight programs and more recently for the next generation human space systems. Since its first use at NASA, PRA has become recognized throughout the Agency as a method of assessing complex mission risks as part of an overall approach to assuring safety and mission success throughout project lifecycles. PRA is now included as a requirement during the design phase of both NASA next generation manned space vehicles as well as for high priority robotic missions. The influence of PRA on GOES-R design and operation concepts are discussed in detail. The GOES-R PRA is unique at NASA for its early implementation. It also represents a pioneering effort to integrate risks from both Spacecraft (SC) and Ground Segment (GS) to fully assess the probability of achieving mission objectives. PRA analysts were actively involved in system engineering and design engineering to ensure that a comprehensive set of technical risks were correctly identified and properly understood from a design and operations perspective. The analysis included an assessment of SC hardware and software, SC fault management system, GS hardware and software, common cause failures, human error, natural hazards, solar weather and infrastructure (such as network and telecommunications failures, fire). PRA findings directly resulted in design changes to reduce SC risk from micro-meteoroids. PRA results also led to design changes in several SC subsystems, e.g. propulsion, guidance, navigation and control (GNC), communications, mechanisms, and command and data handling (C&DH). The fault tree approach assisted in the development of the fault management system design. Human error analysis, which examined human response to failure, indicated areas where automation could reduce the overall probability of gaps in operation by half. In addition, the PRA brought to light many potential root causes of system disruptions, including earthquakes, inclement weather, solar storms, blackouts and other extreme conditions not considered in the typical reliability and availability analyses. Ultimately the PRA served to identify potential failures that, when mitigated, resulted in a more robust design, as well as to influence the program's concept of operations. The early and active integration of PRA with system and design engineering provided a well-managed approach for risk assessment that increased reliability and availability, optimized lifecyc1e costs, and unified the SC and GS developments.
Kalia, Prince↗
System Definition Phase and Acquisition Phase Project Plan for Small Astronomy Satellite SAS-D
This Project Plan for the Small Astronomy Satellite (SAS-D) is Goddard Space Flight Center's plan for accomplishing the project. It is issued in compliance with NASA Handbook NHB 7121.2 and NMI 7120.1, dated May 4, 1970, Subject: Approval and Implementation of Office of Space Science and Applications (OSSA) Research and Development (R&D) Projects. The Project Plan, as approved by GSFC executive management and NASA Headquarters, is the project manager's charter and defines his specific plan of action. System definition phase activities of the SAS-D Project will be a continuation of the analytical work that established the overall feasibility of the project. The system concept derived from that analytical work is defined in the Phase A (Mission Definition Phase) technical report. System definition phase activities will include detailed engineering analysis and preliminary breadboarding necessary to establish a single project approach from the feasible approaches. This document will be revised at the end of the system definition phase to provide greater detail on acquisition phase planning and to specify a specific system design.
Donald A Krueger↗
NASA space transportation plans and roles of a mixed fleet
An account is given of the results of a September, 1987 NASA 'mixed fleet' launching resources/scheduling study that predicated capability projections on a fleet of available ELVs. The launch capability projections extended as far as 1995, and in their later phases encompassed the resumption of Space Shuttle operations and the availability of Orbital Maneuvering Vehicle, which could accomplish such things as the reboosting of the Hubble Space Telescope in 1991, and even the Shuttle-Derived Vehicle, of which two distinct concepts are presently being considered; both would heavily rely on Space Shuttle hardware, but would be unmanned.
Branscome, Darrell R.↗
Materials Data on V2AsC by Materials Project
V2CAs is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. V+3.50+ is bonded to three equivalent C4- and three equivalent As3- atoms to form a mixture of distorted corner, edge, and face-sharing VAs3C3 octahedra. The corner-sharing octahedra tilt angles range from 0–41°. All V–C bond lengths are 2.08 Å. All V–As bond lengths are 2.55 Å. C4- is bonded to six equivalent V+3.50+ atoms to form edge-sharing CV6 octahedra. As3- is bonded in a 6-coordinate geometry to six equivalent V+3.50+ atoms.
36 MATERIALS SCIENCE↗
Materials Data on Cr2GaN by Materials Project
Cr2GaN is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Cr is bonded in a 3-coordinate geometry to three equivalent Ga and three equivalent N atoms. All Cr–Ga bond lengths are 2.68 Å. All Cr–N bond lengths are 1.96 Å. Ga is bonded to six equivalent Cr atoms to form distorted GaCr6 cuboctahedra that share corners with six equivalent NCr6 octahedra, edges with six equivalent GaCr6 cuboctahedra, and edges with six equivalent NCr6 octahedra. The corner-sharing octahedral tilt angles are 21°. N is bonded to six equivalent Cr atoms to form NCr6 octahedra that share corners with six equivalent GaCr6 cuboctahedra, edges with six equivalent GaCr6 cuboctahedra, and edges with six equivalent NCr6 octahedra.
36 MATERIALS SCIENCE↗
Materials Data on CsYbSe2 by Materials Project
CsYbSe2 is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Cs1+ is bonded in a 6-coordinate geometry to six equivalent Se2- atoms. All Cs–Se bond lengths are 3.64 Å. Yb3+ is bonded to six equivalent Se2- atoms to form edge-sharing YbSe6 octahedra. All Yb–Se bond lengths are 2.96 Å. Se2- is bonded to three equivalent Cs1+ and three equivalent Yb3+ atoms to form a mixture of distorted edge, face, and corner-sharing SeCs3Yb3 octahedra. The corner-sharing octahedra tilt angles range from 0–41°.
36 MATERIALS SCIENCE↗
Materials Data on Ti2GaC by Materials Project
Ti2GaC is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ti is bonded in a 3-coordinate geometry to three equivalent Ga and three equivalent C atoms. All Ti–Ga bond lengths are 2.84 Å. All Ti–C bond lengths are 2.11 Å. Ga is bonded in a 12-coordinate geometry to six equivalent Ti atoms. C is bonded to six equivalent Ti atoms to form edge-sharing CTi6 octahedra.
36 MATERIALS SCIENCE↗
Materials Data on Ti2AlC by Materials Project
Ti2AlC is H-Phase structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ti is bonded in a 3-coordinate geometry to three equivalent Al and three equivalent C atoms. All Ti–Al bond lengths are 2.89 Å. All Ti–C bond lengths are 2.11 Å. Al is bonded to six equivalent Ti and six equivalent Al atoms to form distorted AlTi6Al6 cuboctahedra that share corners with six equivalent AlTi6Al6 cuboctahedra, corners with six equivalent CTi6 octahedra, edges with six equivalent AlTi6Al6 cuboctahedra, edges with six equivalent CTi6 octahedra, and faces with six equivalent AlTi6Al6 cuboctahedra. The corner-sharing octahedral tilt angles are 19°. All Al–Al bond lengths are 3.07 Å. C is bonded to six equivalent Ti atoms to form CTi6 octahedra that share corners with six equivalent AlTi6Al6 cuboctahedra, edges with six equivalent AlTi6Al6 cuboctahedra, and edges with six equivalent CTi6 octahedra.
36 MATERIALS SCIENCE↗
Materials Data on LiGa by Materials Project
LiGa is Zintl Phase structured and crystallizes in the cubic Fd-3m space group. The structure is three-dimensional and consists of two LiGa frameworks. Li is bonded to four equivalent Ga atoms to form distorted corner-sharing LiGa4 tetrahedra. All Li–Ga bond lengths are 2.71 Å. Ga is bonded to four equivalent Li atoms to form distorted corner-sharing GaLi4 tetrahedra.
36 MATERIALS SCIENCE↗