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At least 505 records · Page 28

User guide to the Magellan synthetic aperture radar images

The Magellan radar-mapping mission collected a large amount of science and engineering data. Now available to the general scientific community, this data set can be overwhelming to someone who is unfamiliar with the mission. This user guide outlines the mission operations and data set so that someone working with the data can understand the mapping and data-processing techniques used in the mission. Radar-mapping parameters as well as data acquisition issues are discussed. In addition, this user guide provides information on how the data set is organized and where specific elements of the set can be located.

Wall, Stephen D.↗

Exobiology opportunities from Discovery-class missions

Discovery-class missions that are now planned, and those in the concept stage, have the potential to expand our knowledge of the origins and evolution of biogenic compounds, and ultimately, of the origins of life in the solar system. This class of missions, recently developed within NASA's Solar System Exploration Program, is designed to meet important scientific objectives within stringent guidelines--$150 million cap on development cost and a 3-year cap on the development schedule. The Discovery Program will effectively enable "faster, cheaper" missions to explore the inner solar system. The first two missions are Mars Environmental Survey (MESUR) Pathfinder and Near Earth Asteroid Rendezvous (NEAR). MESUR Pathfinder will be the first Discovery mission, with launch planned for November/December 1996. It will be primarily a technical demonstration and validation of the MESUR Program--a network of automated landers to study the internal structure, meteorology, and surface properties of Mars. Besides providing engineering data, Pathfinder will carry atmospheric instrumentation and imaging capabilities, and may deploy a microrover equipped with an alpha proton X-ray spectrometer to determine elemental composition, particularly the lighter elements of exobiological interest. NEAR is expected to be launched in 1998 and to rendezvous with a near-Earth asteroid for up to 1 year. During this time, the spacecraft will assess the asteroid's mass, size, density, map its surface topography and composition, determine its internal properties, and study its interaction with the interplanetary environment. A gamma ray or X-ray spectrometer will be used to determine elemental composition. An imaging spectrograph, with 0.35 to 2.5 micron spectral range, will be used to determine the asteroid's compositional disbribution. Of the 11 Discovery mission concepts that have been designated as warranting further study, several are promising in terms of determining the composition and chemical evolution of organic matter on small planetary bodies. The following mission concepts are of particular interest to the Exobiology Program: Cometary coma chemical composition, comet nucleus tour, near earth asteroid returned sample, small missions to asteroids and comets, and solar wind sample return. The following three Discovery mission concepts that have been targeted for further consideration are relevant to the study of the evolution of biogenic compounds: Comet nucleus penetrator, mainbelt asteroid rendezvous explorer, and the Mars polar Pathfinder.

Meyer, Michael A.↗

Flight and Static Exhaust Flow Properties of an F110-GE-129 Engine in an F-16XL Airplane During Acoustic Tests

The exhaust flow properties (mass flow, pressure, temperature, velocity, and Mach number) of the F110-GE-129 engine in an F-16XL airplane were determined from a series of flight tests flown at NASA Dryden Flight Research Center, Edwards, California. These tests were performed in conjunction with NASA Langley Research Center, Hampton, Virginia (LARC) as part of a study to investigate the acoustic characteristics of jet engines operating at high nozzle pressure conditions. The range of interest for both objectives was from Mach 0.3 to Mach 0.9. NASA Dryden flew the airplane and acquired and analyzed the engine data to determine the exhaust characteristics. NASA Langley collected the flyover acoustic measurements and correlated these results with their current predictive codes. This paper describes the airplane, tests, and methods used to determine the exhaust flow properties and presents the exhaust flow properties. No acoustics results are presented.

Holzman, Jon K.↗

The historical contribution of solid rocket motors to the one centimeter debris population

The measured small particle population in earth orbit contains cm-sized objects that are not accounted for by breakup fragments. It was proposed that slag ejection during solid rocket motor burn is a contributor to this population. The direct evidence for such slag ejection follows from: observations of the exhausts of vehicles in flight, and engineering data from static firings. A source model is presented to account for the contribution of slag expulsion from solid rocket motors to the debris population. The mass and velocity distribution of the slag effluents are taken into account and used as a source term in the debris environment model. The model is based on the available observation data and on models for slag development and ejection.

Jackson, Albert↗

Subsurface Structure in the Martian Polar Layered Deposits: The Deep Space 2 Impact Accelerometry Experiment

While primarily a technology demonstration mission, the New Millenium Mars Microprobes (also known as Deep Space 2, or simply DS2)will also provide the first in situ science measurements of the martian subsurface. The DS2 impact accelerometry experiment will provide both engineering data about the depth of probe emplacement and science data about the physical nature of the subsurface at the probes' landing sites. Little is known about the detailed physical properties or small-scale vertical structure of the subsurface at the DS2 landing site in the southern martian polar layered deposits. Imaging data from the Viking Orbiters and Mars Global Surveyor reveal alternating bands of light and dark material in this region with thicknesses at least as small as the limit of resolution, about 10 m. The overall composition of these layers is poorly constrained, but generally thought to be a mixture of dust and ice with the layers being caused by variations in the dust/ice ratio, or perhaps by dust deposits of different densities. Low thermal inertias in the region suggest that the top few centimeters of the surface are composed of a mantling of fine-grained dust. However, 3.5-cm radar returns indicate that the maximum depth of this dust is not greater than a few tens of centimeters. Thermal models generally agree that, while the layered deposits do provide a potential near-surface reservoir for ice, the uppermost few centimeters to meters in these regions are likely to be ice-free because of sublimation losses. Finally, while it is generally agreed that the layered deposits are the product of variations in the martian climate, no direct correlation has been made between band sequences and specific climate changes. Our intention is to shed light on some of these questions about the martian polar layered deposits by using the DS2 accelerometry experiment to determine the physical nature of the layered deposits, and to detect the presence of any subsurface layering of dust, ice, and/or rock. In the process, we will also determine the final resting depth of the two microprobes, an important parameter in the interpretation of other DS2 experiments.

Moersch, J. E.↗

Autonomous Satellite Command and Control Through the World Wide Web

The Automated Space System Experimental Testbed (ASSET) system is a simple yet comprehensive real-world operations network being developed. Phase 3 of the ASSET Project was January-December 1997 and is the subject of this report. This phase permitted SSDL and its project partners to expand the ASSET system in a variety of ways. These added capabilities included the advancement of ground station capabilities, the adaptation of spacecraft on-board software, and the expansion of capabilities of the ASSET management algorithms. Specific goals of Phase 3 were: (1) Extend Web-based goal-level commanding for both the payload PI and the spacecraft engineer. (2) Support prioritized handling of multiple (PIs) Principle Investigators as well as associated payload experimenters. (3) Expand the number and types of experiments supported by the ASSET system and its associated spacecraft. (4) Implement more advanced resource management, modeling and fault management capabilities that integrate the space and ground segments of the space system hardware. (5) Implement a beacon monitoring test. (6) Implement an experimental blackboard controller for space system management. (7) Further define typical ground station developments required for Internet-based remote control and for full system automation of the PI-to-spacecraft link. Each of those goals are examined. Significant sections of this report were also published as a conference paper. Several publications produced in support of this grant are included as attachments. Titles include: 1) Experimental Initiatives in Space System Operations; 2) The ASSET Client Interface: Balancing High Level Specification with Low Level Control; 3) Specifying Spacecraft Operations At The Product/Service Level; 4) The Design of a Highly Configurable, Reusable Operating System for Testbed Satellites; 5) Automated Health Operations For The Sapphire Spacecraft; 6) Engineering Data Summaries for Space Missions; and 7) Experiments In Automated Health Assessment And Notification For The Sapphire Microsatellite.

Cantwell, Brian↗

Mode-Stirred Method Implementation for HIRF Susceptibility Testing and Results Comparison with Anechoic Method

This paper describes the implementation of mode-stirred method for susceptibility testing according to the current DO-160D standard. Test results on an Engine Data Processor using the implemented procedure and the comparisons with the standard anechoic test results are presented. The comparison experimentally shows that the susceptibility thresholds found in mode-stirred method are consistently higher than anechoic. This is consistent with the recent statistical analysis finding by NIST that the current calibration procedure overstates field strength by a fixed amount. Once the test results are adjusted for this value, the comparisons with the anechoic results are excellent. The results also show that test method has excellent chamber to chamber repeatability. Several areas for improvements to the current procedure are also identified and implemented.

Nguyen, Truong X.↗

Engineering Analysis Using a Web-based Protocol

This paper reviews the development of a web-based framework for engineering analysis. A one-dimensional, high-speed analysis code called LAPIN was used in this study, but the approach can be generalized to any engineering analysis tool. The web-based framework enables users to store, retrieve, and execute an engineering analysis from a standard web-browser. We review the encapsulation of the engineering data into the eXtensible Markup Language (XML) and various design considerations in the storage and retrieval of application data.

Schoeffler, James D.↗

The MER/CIP Portal for Ground Operations

We developed the Mars Exploration Rover/Collaborative Information Portal (MER/CIP) to facilitate MER operations. MER/CIP provides a centralized, one-stop delivery platform integrating science and engineering data from several distributed heterogeneous data sources. Key issues for MER/CIP include: 1) Scheduling and schedule reminders; 2) Tracking the status of daily predicted outputs; 3) Finding and analyzing data products; 4) Collaboration; 5) Announcements; 6) Personalization.

Chan, Louise↗

Initial closed operation of the CELSS Test Facility Engineering Development Unit

As part of the NASA Advanced Life Support Flight Program, a Controlled Ecological Life Support System (CELSS) Test Facility Engineering Development Unit has been constructed and is undergoing initial operational testing at NASA Ames Research Center. The Engineering Development Unit (EDU) is a tightly closed, stringently controlled, ground-based testbed which provides a broad range of environmental conditions under which a variety of CELSS higher plant crops can be grown. Although the EDU was developed primarily to provide near-term engineering data and a realistic determination of the subsystem and system requirements necessary for the fabrication of a comparable flight unit, the EDU has also provided a means to evaluate plant crop productivity and physiology under controlled conditions. This paper describes the initial closed operational testing of the EDU, with emphasis on the hardware performance capabilities. Measured performance data during a 28-day closed operation period are compared with the specified functional requirements, and an example of inferring crop growth parameters from the test data is presented. Plans for future science and technology testing are also discussed. Published by Elsevier Science Ltd on behalf of COSPAR.

Lettuce/growth & development/metabolism↗

Environmental impact analysis with the airspace concept evaluation system

The National Aeronautics and Space Administration (NASA) Ames Research Center has developed the Airspace Concept Evaluation System (ACES), which is a fast-time simulation tool for evaluating Air Traffic Management (ATM) systems. This paper describes linking a capability to ACES which can analyze the environmental impact of proposed future ATM systems. This provides the ability to quickly evaluate metrics associated with environmental impacts of aviation for inclusion in multi-dimensional cost-benefit analysis of concepts for evolution of the National Airspace System (NAS) over the next several decades. The methodology used here may be summarized as follows: 1) Standard Federal Aviation Administration (FAA) noise and emissions-inventory models, the Noise Impact Routing System (NIRS) and the Emissions and Dispersion Modeling System (EDMS), respectively, are linked to ACES simulation outputs; 2) appropriate modifications are made to ACES outputs to incorporate all information needed by the environmental models (e.g., specific airframe and engine data); 3) noise and emissions calculations are performed for all traffic and airports in the study area for each of several scenarios, as simulated by ACES; and 4) impacts of future scenarios are compared to the current NAS baseline scenario. This paper also provides the results of initial end-to-end, proof-of-concept runs of the integrated ACES and environmental-modeling capability. These preliminary results demonstrate that if no growth is likely to be impeded by significant environmental impacts that could negatively affect communities throughout the nation.

Augustine, Stephen↗

Inspection of the Math Model Tools for On-Orbit Assessment of Impact Damage Report

In Spring of 2005, the NASA Engineering Safety Center (NESC) was engaged by the Space Shuttle Program (SSP) to peer review the suite of analytical tools being developed to support the determination of impact and damage tolerance of the Orbiter Thermal Protection Systems (TPS). The NESC formed an independent review team with the core disciplines of materials, flight sciences, structures, mechanical analysis and thermal analysis. The Math Model Tools reviewed included damage prediction and stress analysis, aeroheating analysis, and thermal analysis tools. Some tools are physics-based and other tools are empirically-derived. Each tool was created for a specific use and timeframe, including certification, real-time pre-launch assessments, and real-time on-orbit assessments. The tools are used together in an integrated strategy for assessing the ramifications of impact damage to tile and RCC. The NESC teams conducted a peer review of the engineering data package for each Math Model Tool. This report contains the summary of the team observations and recommendations from these reviews.

Harris, Charles E.↗

Engineering sensors for the Cassini spacecraft

The intent of this paper is to review the subsystems of the Cassini spacecraft and to discuss the types of devices that are used to collect engineering data for each of these subsystems.

vehicle health management fault protection spacecr↗

Mars Pathfinder

Mars Pathfinder, launching in December 1996 and landing on Mars on July 4, 1997, will demonstrate a low-cost delivery system to the surface of Mars for follow-on landers. Objectives are the return of engineering data, panoramic images of the Martian surface, microrover experiments, etc. A technical mission description is included.

Mars Pathfinder Spacecraft NASA JPL↗

NASA Exploration Launch Projects Overview: The Crew Launch Vehicle and the Cargo Launch Vehicle Systems

The U.S. Vision for Space Exploration (January 2004) serves as the foundation for the National Aeronautics and Space Administration's (NASA) strategic goals and objectives. As the NASA Administrator outlined during his confirmation hearing in April 2005, these include: 1) Flying the Space Shuttle as safely as possible until its retirement, not later than 2010. 2) Bringing a new Crew Exploration Vehicle (CEV) into service as soon as possible after Shuttle retirement. 3) Developing a balanced overall program of science, exploration, and aeronautics at NASA, consistent with the redirection of the human space flight program to focus on exploration. 4) Completing the International Space Station (ISS) in a manner consistent with international partner commitments and the needs of human exploration. 5) Encouraging the pursuit of appropriate partnerships with the emerging commercial space sector. 6) Establishing a lunar return program having the maximum possible utility for later missions to Mars and other destinations. In spring 2005, the Agency commissioned a team of aerospace subject matter experts to perform the Exploration Systems Architecture Study (ESAS). The ESAS team performed in-depth evaluations of a number of space transportation architectures and provided recommendations based on their findings? The ESAS analysis focused on a human-rated Crew Launch Vehicle (CLV) for astronaut transport and a heavy lift Cargo Launch Vehicle (CaLV) to carry equipment, materials, and supplies for lunar missions and, later, the first human journeys to Mars. After several months of intense study utilizing safety and reliability, technical performance, budget, and schedule figures of merit in relation to design reference missions, the ESAS design options were unveiled in summer 2005. As part of NASA's systems engineering approach, these point of departure architectures have been refined through trade studies during the ongoing design phase leading to the development phase that begins in 2008. Comprehensive reviews of engineering data and business assessments by both internal and independent reviewers serve as decision gates to ensure that systems can fully meet customer and stakeholder requirements. This paper provides the current CLV and CaLV configuration designs and gives examples of the progress being made during the first year of this significant effort. Safe, reliable, cost-effective space transportation systems are a foundational piece of America s future in space and the next step in realizing the plan for revitalizing lunar capabilities on the passageway to the human exploration of Mars. While building on legacy knowledge and heritage hardware for risk reduction, NASA will apply lessons learned from developing these new launch vehicles to the growth path for future missions. The elements for mission success and continued U.S. leadership in space have been assembled over the past year. As NASA designs and develops these two new systems over the next dozen years, visible progress, such as that reported in this paper, may sustain the national will to stay the course across political administrations and weather the inevitable trials that will be experienced during this challenging endeavor.

Snoddy, Jimmy R.↗

Phoenix Mars Scout UHF Relay-Only Operations

The Phoenix Mars Scout Lander will launch in August 2007 and land on the northern plains of Mars in May of 2008. In a departure from traditional planetary surface mission operations, it will have no direct-to-Earth communications capability and will rely entirely on Mars-orbiting relays in order to facilitate command and control as well as the return of science and engineering data. The Mars Exploration Rover missions have demonstrated the robust data-return capability using this architecture, and also have demonstrated the capability of using this method for command and control. The Phoenix mission will take the next step and incorporate this as the sole communications link. Operations for 90 Sols will need to work within the constraints of Odyssey and Mars Reconnaissance Orbiter communications availability, anomalies must be diagnosed and responded to through an intermediary and on-board fault responses must be tolerant to loss of a relay. These and other issues pose interesting challenges and changes in paradigm for traditional space operations and spacecraft architecture, and the approach proposed for the Phoenix mission is detailed herein.

fault protection↗

Nulling at the Keck Interferometer

The nulling mode of the Keck Interferometer is being commissioned at the Mauna Kea summit. The nuller combines the two Keck telescope apertures in a split-pupil mode to both cancel the on-axis starlight and to coherently detect the residual signal. The nuller, working at 10 um, is tightly integrated with the other interferometer subsystems including the fringe and angle trackers, the delay lines and laser metrology, and the real-time control system. Since first 10 um light in August 2004, the system integration is proceeding with increasing functionality and performance, leading to demonstration of a 100:1 on-sky null in 2005. That level of performance has now been extended to observations with longer coherent integration times. An overview of the overall system is presented, with emphasis on the observing sequence, phasing system, and differences with respect to the V2 system, along with a presentation of some recent engineering data.

interferometry↗