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At least 1,423 records · Page 79

Jet Propulsion Laboratory: Annual Report 2006

Nothing is as gratifying in space exploration as when we are surprised by the unexpected. Much of our work progresses in an orderly way, from concept to plan to creation to finding. But now and then we are caught off-guard by something startlingly new, and it is these moments that make our hearts race and leave us with many of our most compelling memories. And 2006 was an exceptional year for the unforeseen. One of our orbiters shocked many with stark proof that liquid water, the seemingly long-gone force that reshaped so much of the scenery of Mars, still flows there today,at least in occasional bursts. Another spacecraft caught us by surprise with photos of Yellowstone-like geysers on one of Saturn's seemingly nondescript moons, Enceladus. A spaceborne observatory created to plumb the life histories of stars and galaxies showed off a completely unexpected talent when it revealed the day and night faces of a fire and ice planet far beyond our solar system 40 light-years away. A newly launched Earth observer revealed that the clouds that decorate our own planet are not what we thought them to be in many ways. Of course, not all of the high points of the year arrived on our doorstep in such unexpected ways. There was also great drama when missions came off exactly as planned, such as when Stardust's sample return capsule made a flawless landing in the Utah desert, bringing home samples of cometary and interstellar dust. Mars Reconnaissance Orbiter slipped into orbit around the red planet exactly as planned. Numerous other missions and technology programs likewise made great achievements during the year. In all, 17 spacecraft and six instruments were stationed across the solar system, studying our own world, other planets, comets and the deeper universe. All of these achievements were enabled by many teams and systems at the Laboratory. The Deep Space Network of communications complexes across three continents supported all of NASA's solar system missions, and several from our international partners, while looking ahead to reinvent itself for the future. Technologists were at work creating innovations both for NASA missions and terrestrial uses. JPL's community of scientific researchers was equally busy coordinating the science activities of our missions and pursuing independent investigations. None of this would be possible without the support of business and administrative teams dedicated to making the Laboratory's institutional environment as world-class as its technical face, or the public engagement specialists who bring the experience of space to the country's diverse publics. All of our missions in one way or another support our nation's Vision for Space Exploration, which envisages a gradually widening robotic and human presence across the solar system in the years ahead.

National Aeronautics and Space Administration (NAS↗

Evaluation of advanced propulsion options for the next manned transportation system: Propulsion evolution study

The objectives were to examine launch vehicle applications and propulsion requirements for potential future manned space transportation systems and to support planning toward the evolution of Space Shuttle Main Engine (SSME) and Space Transportation Main Engine (STME) engines beyond their current or initial launch vehicle applications. As a basis for examinations of potential future manned launch vehicle applications, we used three classes of manned space transportation concepts currently under study: Space Transportation System Evolution, Personal Launch System (PLS), and Advanced Manned Launch System (AMLS). Tasks included studies of launch vehicle applications and requirements for hydrogen-oxygen rocket engines; the development of suggestions for STME engine evolution beyond the mid-1990's; the development of suggestions for STME evolution beyond the Advanced Launch System (ALS) application; the study of booster propulsion options, including LOX-Hydrocarbon options; the analysis of the prospects and requirements for utilization of a single engine configuration over the full range of vehicle applications, including manned vehicles plus ALS and Shuttle C; and a brief review of on-going and planned LOX-Hydrogen propulsion technology activities.

Spears, L. T.↗

Runway Independent Aircraft Extremely Short Takeoff and Landing Regional Airliner: The Model 110

Airports throughout the United States are plagued with growing congestion. With the increase in air traffic predicted in the next few years, congestion will worsen. The accepted solution of building larger airplanes to carry more travelers is no longer a viable option, as airports are unable to accommodate larger aircraft without expensive infrastructure changes. Past NASA research has pointed to the need for a new approach, which can economically and safely utilize smaller airports. To study this option further, NASA requested the California Polytechnic State University at San Luis Obispo (Cal Poly/SLO) to design a baseline aircraft to be used for system studies. The requirements put forth by NASA are summarized. The design team was requested to create a demonstrator vehicle, which could be built without requiring enabling technology development. To this end, NASA requested that the tested and proven high-lift system of the Boeing C-17 Globemaster III be combined with the fuselage of the BAe-146. NASA also requested that Cal Poly determine the availability and usability of underutilized airports starting with California, then expanding if time and funds permitted to the U.S.

Hall, David W.↗

Ascent performance issues of a vertical-takeoff rocket launch vehicle

Advanced manned launch systems studies under way at the NASA Langley Research Center are part of a broader effort that is examining options for the next manned space transportation system to be developed by the United States. One promising concept that uses near-term technologies is a fully reusable, two-stage vertical-takeoff rocket vehicle. This vehicle features parallel thrusting of the booster and orbiter with the booster cross-feeding the propellant to the orbiter until staging. In addition, after staging, the booster glides back unpowered to the launch site. This study concentrated on two issues that could affect the ascent performance of this vehicle. The first is the large gimbal angle range required for pitch trim until staging because of the propellant cross-feed. Results from this analysis show that if control is provided by gimballing of the rocket engines, they must gimbal greater than 20 deg, which is excessive when compared with current vehicles. However, this analysis also showed that this limit could be reduced to 10 deg if gimballing were augmented by throttling the booster engines. The second issue is the potential influence of off-nominal atmospheric conditions (density and winds) on the ascent performance. This study showed that a robust guidance algorithm could be developed that would insure accurate insertion, without prelaunch atmospheric knowledge.

Powell, Richard W.↗

Air cargo market outlook and impact via the NASA CLASS project

An overview is given of the Cargo/Logistics Airlift Systems Study (CLASS) project which was a 10 man-year effort carried out by two contractor teams, aimed at defining factors impacting future system growth and obtaining market requirements and design guidelines for future air freighters. Growth projection was estimated by two approaches: one, an optimal systems approach with a more efficient and cost effective system considered as being available in 1990; and the other, an evolutionary approach with an econometric behavior model used to predict long term evolution from the present system. Both approaches predict significant growth in demand for international air freighter services and less growth for U.S. domestic services. Economic analysis of air freighter fleet options indicate very strong market appeal of derivative widebody transports in 1990 with little incentive to develop all new dedicated air freighters utilizing the 1990's technology until sometime beyond the year 2000. Advanced air freighters would be economically attractive for a wide range of payload sizes (to 500 metric tons), however, if a government would share in the RD and T costs by virtue of its needs for a slightly modified version of a civil air freighter design (a.g. military airlifter).

Winston, M. M.↗

Approaches to the utilization of space for CO2 research

A system study of the potential of space technology to monitor climate changes and improve the understanding of the coupling beteen CO2 and cloud cover is summarized. The basis for the study is scientific data requirements pertinent to the U.S. Department of Energy's CO2 Research Program. The capabilities of space-based sensor systems are matched to meet these requirements. New sensor system concepts are identified, including a Space Shuttle-launched recalibration package to provide for continuity of measurement and recalibration between satellites, a high-orbit radiation budget satellite, or parallax sensor to measure cloud altitude, a passive method for the direct measurements of CO2 and a high-altitude powered platform to monitor select regional parameters. Space-based sensor systems that could be the development focus for the time frames of 0-5, 5-10 and 10-20 years are recommended.

Glaser, P.↗

Comets

The nature, history, and evolution of comets are considered. Cometary ions, formed by photoionization and other processes, are forced into a highly structured ion tail by the interaction with the solar wind. The importance of comets to solar-system studies lies in the possibilities that they are well-preserved samples of either the interstellar cloud which collapsed to form the solar system or the planetesimals from which the outer planets accumulated, and that they provided either the prebiotic complex molecules from which life evolved or some volatiles necessary for the evolution of these molecules.

Neugebauer, M.↗

Space Shuttle aft propulsion system enhancements

The characteristics of an aft propulsion system for the Space Shuttle Orbiter that would combine the propellant storage and pressurization systems of the Orbital Maneuvering System (OMS) and the Reaction Control System (RCS) are discussed. The paper describes the current OMS and RCS design development, the operation and flight experience, and the status of the aft propulsion system study (which is a part of the NASA Assured Shuttle Availability Program). Diagrams of the OMS, the RCS, and the integrated aft propulsion system are presented.

Hooper, John C., III↗

A Detailed Study of Two Optically Selected, High-Redshift Clusters of Galaxies

We are obtaining detailed X-ray spectral and structural data for two distant, optically-selected clusters of galaxies which are known X-ray emitters, CL1324+3011 at z = 0.76 and CL,1604+4304 at z = 0.90. These observations will allow us to place accurate constraints on the temperature, surface-brightness profile, and mass fraction of the intracluster medium in rich, optically-selected clusters at very high redshift. The two target clusters are the most well-studied systems at z greater than 0.7 in the optical and infrared regimes; therefore, with the addition of the XMM data, we plan to study the specifies of the relationship between the X-ray and optical properties and their implications for galaxy and cluster evolution.

Lubin, Lori M.↗

A Detailed Study of Two Optically-Selected, High-Redshift Clusters of Galaxies

We are obtaining detailed X-ray spectral and structural data for two distant, optically-selected clusters of galaxies which are known X-ray emitters, CL1324+3011 at z=0.76 and CL1604+4304 at z=0.90. These observations will allow us to place accurate constraints on the temperature, surface-brightness profile, and mass fraction of the intracluster medium in rich, optically-selected clusters at very high redshift. The two target clusters are the most well-studied systems at z greater than 0.7 in the optical and infrared regimes; therefore, with the addition of the XMM data, we plan to study the specifics of the relationship between the X-ray and optical properties and their implications for galaxy and cluster evolution.

Lubin, Lori M.↗

ARM/GCSS/SPARC TWP-ICE CRM Intercomparison Study

Specifications are provided for running a cloud-resolving model (CRM) and submitting results in a standardized format for inclusion in a n intercomparison study and archiving for public access. The simulated case study is based on measurements obtained during the 2006 Tropical Warm Pool - International Cloud Experiment (TWP-ICE) led by the U. S. department of Energy Atmospheric Radiation Measurement (ARM) program. The modeling intercomparison study is based on objectives developed in concert with the Stratospheric Processes And their Role in Climate (SPARC) program and the GEWEX cloud system study (GCSS) program. The Global Energy and Water Cycle Experiment (GEWEX) is a core project of the World Climate Research PRogramme (WCRP).

Fridlind, Ann↗

Multipoint Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric Vertical Takeoff Landing Air Taxi

This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400 nm mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.

gas turbine↗

Multi-Point Design and Optimization of a Turboshaft Engine for a Tiltwing Turboelectric VTOL Air Taxi

This paper describes the design of a turboshaft engine for a tiltwing air taxi application. In this case, the tiltwing air taxi is intended to fly a 400-nautical mile mission with up to fifteen passengers. Engine requirements for the concept engine are taken from aircraft system studies where thrust is produced by four propellers driven by electric motors and powered by a single gas turbine engine. The purpose of this paper is to perform a cycle design optimization that minimizes fuel consumption and weight while respecting current technology limitations to meet mission requirements. To achieve results, the engine overall pressure ratio and maximum temperature at the exit of the combustor are set as the design parameters. Several sensitivity studies are also performed to visualize optimization trends. Results of the optimization study show solutions are heavily dependent on engine cooling flow requirements and exact mission requirements. This engine is intended for use in large system optimization research.

Optimization↗

Studies of Shuttle orbiter arrestment system

Scale model studies of the Shuttle Orbiter Arrestment System (AS) were completed with a 1/27.5-scale model at the NASA Langley Research Center. The purpose of these studies was to determine the proper configuration for a net arrestment system to bring the orbiter to a safe stop with minimal damage in the event of a runway overrun. Tests were conducted for runway on-centerline and off-centerline engagements at simulated speeds up to approximately 100 knots (full scale). The results of these tests defined the interaction of the net and the orbiter, the dynamics of off-centerline engagements, and the maximum number of vertical net straps that may become entangled with the nose gear. In addition to these tests, a test program with a 1/8-scale model was conducted by the arrestment system contractor, and the results are presented in the appendix.

Davis, Pamela A.↗

Beyond the Baseline 1991: Proceedings of the Space Station Evolution Symposium. Volume 1: Space Station Freedom, part 1

Personnel responsible for Advanced Systems Studies and Advanced Development within the Space Station Freedom Program reported on the results of their work to date. The results of SSF Advanced Studies provide a road map for the evolution of Freedom in terms of user requirements, utilization and operations concepts, and growth options for distributed systems. Regarding these specific systems, special attention is given to: highlighting changes made during restructuring; description of growth paths thru the follow-on and evolution phases; identification of minimum impact provisions to allow flexibility in the baseline; and identification of enhancing and enabling technologies. Products of these tasks include: engineering fidelity demonstrations and evaluations of advanced technology; detailed requirements, performance specifications, and design accommodations for insertion of advanced technology.

Source record↗

Two-micron Laser Atmospheric Wind Sounder (LAWS) pointing/tracking study

The objective of the study was to identify and model major sources of short-term pointing jitter for a free-flying, full performance 2 micron LAWS system and evaluate the impact of the short-term jitter on wind-measurement performance. A fast steering mirror controls system was designed for the short-term jitter compensation. The performance analysis showed that the short-term jitter performance of the controls system over the 5.2 msec round-trip time for a realistic spacecraft environment was = 0.3 micro rad, rms, within the specified value of less than 0.5 micro rad, rms, derived in a 2 micron LAWS System Study. Disturbance modes were defined for: (1) the Bearing and Power Transfer Assembly (BAPTA) scan bearing, (2) the spacecraft reaction wheel torques, and (3) the solar array drive torques. The scan bearing disturbance was found to be the greatest contributing noise source to the jitter performance. Disturbances from the fast steering mirror reaction torques and a boom-mounted cross-link antenna clocking were also considered but were judged to be small compared to the three principal disturbance sources above and were not included in the final controls analysis.

Manlief, Scott↗

Experimental Investigation of Magnesium Powder Combustion With C02 for Mars Ascent Applications

Combustion of metals with CO2 has been identified as a possible propellant for Mars ascent applications. CO2 could be condensed from the Martian atmosphere, reducing the amount of propellant that must be transported from Earth. An attractive feature of this approach compared to other in situ propellant concepts is that no chemical processing on Mars is required. Magnesium has been identified as the most promising metal for this application because it ignites and burns easily in CO2. Preliminary systems studies indicate a 2 to 1 delivered mass advantage for Mg ascent propulsion using in situ C02, as compared to a conventional storable propellant system. The Propulsion Research Center at MSFC is undertaking an experimental investigation of magnesium powder combustion with CO2 in order to provide fundamental data on the combustion performance of Mg powder + CO2 mixtures needed to assess the feasibility of developing a practical Mg powder + CO2 rocket engine. Initial combustion experiments will be carried out in a small scale atmospheric pressure dump combustor. Effects of varying the Mg particle size, firing rate and O/F ratio on combustion stability and efficiency will be investigated. The combustion process will be characterized by optical flame measurements and extraction of combustion product samples. The experimental facility is currently being prepared and combustion experiments will begin during the first quarter of 2005. The final paper will describe the test facility and initial experimental results.

Foote, John P.↗