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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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At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
NASA NTRS1990

Impact delivery and erosion of planetary oceans in the early inner solar system

The terrestrial planets may have acquired oceans of water (and other surface volatiles) as a late-accreting veneer from impacts of comets and carbonaceous asteroids during the period of heavy bombardment 4.5 to 3.5 Gyr ago. On any given body, the efficiency of this mechanism depended on a competition between impact delivery of new volatiles and impact erosion of those already present. For the larger worlds of the inner Solar System, this competition strongly favored the net accumulation of planetary oceans.

Chyba, Christopher F.↗
NASA NTRS1989

Delivery of asteroids and meteorites to the inner solar system

Two major models of asteroid/meteorite demographics are described and reviewed critically: the collisional model of Greenberg and Chapman (1983), and the orbital evolution model of Wetherill (1985). It is shown that each of the two models tends to gloss over the central processes in the other and tends to ignore (and to some degree violate) the key observables that constrain the other model. The uncertainties that prevent definite acceptance of any particular model for the delivery of asteroidal material to the earth are described.

Greenberg, Richard↗
NASA NTRS1989

Conceptual design of a closed loop nutrient solution delivery system for CELSS implementation in a micro-gravity environment

This paper describes the results of a study to develop a conceptual design for an experimental, closed-loop fluid handling system capable of monitoring, controlling, and supplying nutrient solution to higher plants. The Plant Feeder Experiment (PFX) is designed to be flight tested in a micro-gravity (micro-g) environment and was developed under NASA's In-Space Technology Experiments Program (INSTEP). When flown, PFX will provide information on both the generic problems of micro-g fluid handling and the specific problems associated with the delivery of nutrient solution in a micro-g environment. The experimental hardware is designed to fit into two middeck lockers on the Space Shuttle, and incorporates several components that have previously been flight tested.

Schwartzkopf, Steven H.↗
NASA NTRS1990

Factors affecting plant growth in membrane nutrient delivery

The development of the tubular membrane plant growth unit for the delivery of water and nutrients to roots in microgravity has recently focused on measuring the effects of changes in physical variables controlling solution availability to the plants. Significant effects of membrane pore size and the negative pressure used to contain the solution were demonstrated. Generally, wheat grew better in units with a larger pore size but equal negative pressure and in units with the same pore size but less negative pressure. Lettuce also exhibited better plant growth at less negative pressure.

Dreschel, T. W.↗
NASA NTRS1990

Conceptual design of a closed loop nutrient solution delivery system for CELSS implementation in a micro-gravity environment

Described here are the results of a study to develop a conceptual design for an experimental closed loop fluid handling system capable of monitoring, controlling, and supplying nutrient solution to higher plants. The Plant Feeder Experiment (PFE) is designed to be flight tested in a microgravity environment. When flown, the PFX will provide information on both the generic problems of microgravity fluid handling and the specific problems associated with the delivery of the nutrient solution in a microgravity environment. The experimental hardware is designed to fit into two middeck lockers on the Space Shuttle, and incorporates several components that have previously been flight tested.

Schwartzkopf, Steven H.↗
NASA NTRS1991

Terrestrial production vs. extraterrestrial delivery of prebiotic organics to the early Earth

A comprehensive treatment of comet/asteroid interaction with the atmosphere, ensuring surface impact, and resulting organic pyrolysis is required to determine whether more than a negligible fraction of the organics in incident comets and asteroids actually survived collision with Earth. Results of such an investigation, using a smoothed particle hydrodynamic simulation of cometary and asteroidal impacts into both oceans and rock, demonstrate that organics will not survive impacts at velocities approx. greater than 10 km s(exp -1), and that even comets and asteroids as small as 100m in radius cannot be aerobraked to below this velocity in 1 bar atmospheres. However, for plausible dense (10 bar CO2) early atmospheres, there will be sufficient aerobraking during atmospheric passage for some organics to survive the ensuing impact. Combining these results with analytical fits to the lunar impact record shows that 4.5 Gyr ago Earth was accreting at least approx. 10(exp 6) kg yr(exp 1) of intact cometary organics, a flux which thereafter declined with a approx. 100 Myr half-life. The extent to which this influx was augmented by asteroid impacts, as well as the effect of more careful modelling of a variety of conservative approximations, is currently being quantified. These results may be placed in context by comparison with in situ organic production from a variety of terrestrial energy sources, as well as organic delivery by interplanetary dust. Which source dominated the early terrestrial prebiotic inventory is found to depend on the nature of the early terrestrial atmosphere. However, there is an intriguing symmetry: it is exactly those dense CO2 atmospheres where in situ atmospheric production of organic molecules should be the most difficult, in which intact cometary organics would be delivered in large amounts.

Chyba, C. F.↗
NASA NTRS1992

Satellite delivery of B-ISDN services

This paper will address the role of technology in the satellite delivery of B-ISDN services. Satellites excel in serving remote users and in providing multicast and broadcast services. Benefits to potential users employing these satellite broadband services will be examined together with their respective network architecture. Two application requirements are then proposed. The critical technologies needed in the realization of these architectures will be identified.

Kwan, R. K.↗
NASA NTRS1992

Candidate Mission from Planet Earth control and data delivery system architecture

Using a structured, experienced-based approach, Goddard Space Flight Center (GSFC) has assessed the generic functional requirements for a lunar mission control and data delivery (CDD) system. This analysis was based on lunar mission requirements outlined in GSFC-developed user traffic models. The CDD system will facilitate data transportation among user elements, element operations, and user teams by providing functions such as data management, fault isolation, fault correction, and link acquisition. The CDD system for the lunar missions must not only satisfy lunar requirements but also facilitate and provide early development of data system technologies for Mars. Reuse and evolution of existing data systems can help to maximize system reliability and minimize cost. This paper presents a set of existing and currently planned NASA data systems that provide the basic functionality. Reuse of such systems can have an impact on mission design and significantly reduce CDD and other system development costs.

Shapiro, Phillip↗
NASA NTRS1992

Regenerable biocide delivery unit, volume 1

The Microbial Check Valve (MCV), which is currently used aboard the Shuttle Orbiter for disinfection of the potable water supply, is an expendable flow-through canister containing iodinated ion exchange resin. Means for extension of MCV life are desirable to avoid resupply penalties. The Phase 1 Regenerable Biocide Delivery Unit program demonstrated the feasibility of regenerating an MCV in situ, using a strong aqueous elemental iodine solution resulting from diversion of the MCV influent to a packed bed containing iodine crystals. In small column tests, eight manual regenerations of an MCV resin were accomplished. The term Regenerative Microbial Check Valve (RMCV) was adopted describing this new technology. The Phase 2 program resulted in the development of a full scale and fully autonomous prototype RMCV, capable of maintaining residual I(sub 2) levels between 2.0 - 4.0 mg/L for prolonged periods. During six months of testing at the Space Station baseline flow rate of 120 cm(sup 3)/min, the prototype RMCV underwent nine regenerations. RMCV life cycle tests, using a variety of influent streams, were conducted over an eighteen month period to determine the useful lives of MCV's incorporating this new technology and to determine ultimate failure mechanisms. MCV life extensions of 130 fold were demonstrated, limited only by the Phase 2 performance period. Based upon this work, it is certain that RMCV units can be developed to provide unattended biocide addition for the thirty year life of Space Station Freedom, or for other longer duration applications such as a Lunar Base or Mars mission. RMCV technology was also demonstrated capable of delivering, on demand, a concentrated aqueous I(sub 2) solution for potential use as a disinfectant during transient episodes of microbial surface contamination, for the control of biofilm formation, or as a preventative measure in systems which are particularly susceptible to the growth of microorganisms.

Atwater, James E.↗
NASA NTRS1993

A high fidelity video delivery system for real-time flight simulation research

The Flight Systems and Simulation Research Laboratory (Simlab) at the NASA Ames Research Center, utilizes an extensive network of video image generation, delivery, processing, and display systems coupled with a large amplitude Vertical Motion Simulator (VMS) to provide a high fidelity visual environment for flight simulation research. This paper will explore the capabilities of the current Simlab video distribution system architecture with a view toward technical solutions implemented to resolve a variety of video interface, switching, and distribution issues common to many simulation facilities. Technical discussions include a modular approach to a video switching and distribution system capable of supporting both coax and fiber optic video signal transmission, video scan conversion and processing techniques for lab observation and recording, adaptation of image generation and display system video interfaces to industry standards, an all raster solution for 'glass cockpit' configurations encompassing Head up, Head-down, and Out-the-Window display systems.

Wilkins, Daniel A.↗
NASA NTRS1991

A telemedicine health care delivery system

The Interactive Telemedicine Systems (ITS) system was specifically developed to address the ever widening gap between our medical care expertise and our medical care delivery system. The frustrating reality is that as our knowledge of how to diagnose and treat medical conditions has continued to advance, the system to deliver that care has remained in an embryonic stage. This has resulted in millions of people being denied their most basic health care needs. Telemedicine utilizes an interactive video system integrated with biomedical telemetry that allows a physician at a base station specialty medical complex or teaching hospital to examine and treat a patient at multiple satellite locations, such as rural hospitals, ambulatory health centers, correctional institutions, facilities caring for the elderly, community hospital emergency departments, or international health facilities. Based on the interactive nature of the system design, the consulting physician at the base station can do a complete history and physical examination, as if the patient at the satellite site was sitting in the physician's office. This system is described.

Sanders, Jay H.↗
NASA NTRS1993

The ACTS propagation terminal delivery and support

Viewgraphs on the Advanced Communications Technology Satellite (ACTS) propagation terminal delivery and support are included. Topics covered include: the ACTS propagation terminal (APT) development program; terminal overview; physical units; test results; status of terminals and schedule; shipping cartons; and site support.

Stutzman, Warren L.↗
NASA NTRS1994

The network data delivery service: A real-time data connectivity system

A network data-sharing system, the Network Data Delivery Service (NDDS), is discussed. The NDDS system relies on a bipartite model consisting of the following: information producers (sources) and information consumers (sinks). The example provided by a dual-arm robotic system is examined.

Pardo-Castellote, Gerardo↗
NASA NTRS1994

Economical ground data delivery

Data delivery in the Deep Space Network (DSN) involves transmission of a small amount of constant, high-priority traffic and a large amount of bursty, low priority data. The bursty traffic may be initially buffered and then metered back slowly as bandwidth becomes available. Today both types of data are transmitted over dedicated leased circuits. The authors investigated the potential of saving money by designing a hybrid communications architecture that uses leased circuits for high-priority network communications and dial-up circuits for low-priority traffic. Such an architecture may significantly reduce costs and provide an emergency backup. The architecture presented here may also be applied to any ground station-to-customer network within the range of a common carrier. The authors compare estimated costs for various scenarios and suggest security safeguards that should be considered.

Markley, Richard W.↗
NASA NTRS1994

Dynamics of volatile delivery from outer to inner solar system

Owen et al. propose that the Ar excess of Venus compared to Earth was caused by impact of a large icy planetesimal from the outer solar system, where temperatures were low enough for Ar to adhere to ice, about 30 K. A body of solar Ar/Si and C/H similar to Pluto and Triton less than 100 km diameter would suffice. However, direct delivery from the Uranus-Neptune zone to Venus would result in a very high approach velocity, causing erosion rather than accretion of volatiles. It would also be an extremely improbable event. Virtually all icy bodies scattered from the Uranus-Neptune zone to the terrestrial zone were strongly perturbed by Jupiter, but even then arrived at Venus (or Earth) at too-high velocities. What is needed is a 'deboost' of bodies scattered inward from Jupiter by Earth and Venus perturbations, prior to impact into Venus. This has low probability, since the influence radii of Venus and Earth for the high velocities are small compared to that of Jupiter for the lower velocities further out. It is desirable that this problem be examined by an integerator that allows for close approaches, such as developed by Levison and Duncan. However, it would be a long and expensive computation compared to explaining short-period comets to accomplish the third 'deboost' phase. But since close encounters dominate in such distant scattering, an Opik algorithm seems the appropriate reconnaissance tool.

Kaula, W. M.↗
NASA NTRS1997

Sample Delivery and Computer Control Systems for Detecting Leaks in the Main Engines of the Space Shuttle

The main engines of the Space Shuttle use hydrogen and oxygen as the fuel and oxidant. The explosive and fire hazards associated with these two components pose a serious danger to personnel and equipment. Therefore prior to use the main engines undergo extensive leak tests. Instead of using hazardous gases there tests utilize helium as the tracer element. This results in a need to monitor helium in the ppm level continuously for hours. The major challenge in developing such a low level gas monitor is the sample delivery system. This paper discuss a system developed to meet the requirements while also being mobile. Also shown is the calibration technique, stability, and accuracy results for the system.

Griffin, Timothy P.↗
NASA NTRS2000

High Rate Data Delivery Thrust Area

In this paper, a brief description of the high rate data delivery (HRDD) thrust area, its focus and current technical activities being carried out by NASA centers including JPL, academia and industry under this program is provided. The processes and methods being used to achieve active participation in this program are presented. The developments in space communication technologies, which will shape NASA enterprise missions in the 21 st. century, are highlighted.

Bhasin, Kul↗