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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS1984

Summary of current radiation dosimetry results on manned spacecraft

It is pointed out that the experimental data existing on radiation levels inside orbiting spacecraft are currently limited. However, it is recognized that perhaps the single most important constraint to long-term manned space activity may be related to the complex space radiation environment. For this reason, it is important to know the radiological parameters which determine the biological effects of space radiation on humans. Attention is given to radiation dose measurements, LET (linear energy transfer) spectra for HZE particles, and dosimetry data from U.S. manned spaceflights. In particular, data are now available on dose rates in spacecraft at low altitudes (less than 300 km), while insufficient measurements exist for high altitude and high inclination orbits, geostationary orbits, and many orbits in between. Very little data exist on neutron dose and spectra.

Benton, E. V.↗
NASA NTRS1974

Environmental control system development for manned spacecraft 1960-1973

This paper provides an overview of the development of environmental revitalization techniques from their beginnings in caisson and submarine habitats, up to the present time. The use of CO2 adsorbents, such as LiOH and their application to the first U.S. manned spaceflight is described, together with the beginnings of the regenerable CO2 sorber technology using molecular sieves and its ultimate application to Skylab. The concepts and hardware systems used for atmospheric revitalization on all major U.S. ground-based manned tests is detailed, including CO2 reduction and O2 generation processes. Current research and development efforts are also outlined. The paper concludes with a detailed description of the recently completed SSP, the most advanced and complete ECS that has been fabricated to date.

Popma, D. C.↗
NASA NTRS1999

The Use of the Satellite Breakup Risk Assessment Model (SBRAM) to Characterize Collision Risk to Manned Spacecraft

NASA uses environment models such as ORDEM96 to characterize the long-term orbital debris collision hazard for spacecraft in LEO. Occasionally, however, there are breakups of satellites or rocket bodies that create enhanced collision hazard for a period of time. This enhanced collision hazard can pose increased risks to space operations - especially those involving manned missions where the tolerance for risk is very low. NASA has developed SBRAM to simulate the enhanced debris environment in the days and weeks that follow such a breakup. This simulation provides the kind of risk probabilities that can be used by mission planners to consider if changes are warranted for the mission. Announcements of breakups come to NASA from US Space Command as soon as they are identified. The pre-breakup orbit and time of breakup are used to determine the initial conditions of the explosion. SBRAM uses the latest explosion models developed at NASA to simulate a debris cloud for the breakup. The model uses a Monte Carlo technique to create a random debris cloud from the probability distributions in the breakup model. Each piece of debris randomly created in the cloud is propagated in a deterministic manner to include the effects of drag and other orbital perturbations. The detailed geometry of each simulated close approach to the target spacecraft is noted and logged and the collision probability is computed using an estimated probability density in down-range and cross-range positions of both the target spacecraft and debris object. The collision probability is computed from the overlap of these probability densities for each close-approach geometry and summed over all computed conjunctions. Cloud propagation runs over the desired time interval are then repeated until the scale of the collision risk can be estimated to a desired precision. This paper presents an overview of the SBRAM model and a number of examples, both real and hypothetical, to demonstrate its use. In addition, a number of different examples are shown how the data can be used by decision makers on issues such as spacecraft orientation and timing of EVAs.

Matney, Mark J.↗
NASA NTRS2007

Application of Vacuum Swing Adsorption for Carbon Dioxide and Water Vapor Removal from Manned Spacecraft Atmospheres

In NASA's Vision for Space Exploration (Bush, 2004), (Griffin, 2007), humans will once again travel beyond the confines of earth's gravity, this time to remain there for extended periods. These forays will place unprecedented demands on launch systems. They must not only blast out of earth's gravity well as during the Apollo moon missions, but also liftoff the supplies needed to sustain a larger crew over much longer periods. Thus all spacecraft systems, including those for the separation of metabolic carbon dioxide and water from a crewed vehicle, must be minimized with respect to mass, power, and volume. Emphasis is also placed on system robustness both to minimize replacement parts and ensure crew safety when a quick return to earth is not possible. For short-term phases of manned space exploration, such as transit from the earth to the moon, venting of metabolic carbon dioxide and water to space is more efficient than the inclusion of large recycling systems on the spacecraft. The baseline system for the Orion spacecraft is an amine-based vacuum swing system (Smith, Perry et aI., 2006). As part of the development of an alternative approach, a sorbent-based CO2 and H2O removal system (Knox, Adams et aI., 2006), subscale testing was conducted to evaluate potential performance improvements obtainable by recuperating the heat of adsorption to aid in vacuum desorption. This bed design is shown in Figure 1, is depicted here with a lattice structure instead of reticulated foam for heat transfer. The slot widths are approximately 1.2 mm wide and 8.5 mm long. Bed depth is approximately 4.7 mm. Headers (not shown) were produced by the stereo lithography apparatus at MSFC.

Knox, J.↗
NASA NTRS2010

Phase Change Material Trade Study: A Comparison Between Wax and Water for Manned Spacecraft

Phase change material heat sinks have been recognized as an important tool in optimizing thermal control systems for space exploration vehicles and habitats that must deal with widely varying thermal loads and environments. In order to better focus technology investment in this arena, NASA has supported a trade study with the objective of identifying where the best potential pay-off can be found among identified aqueous and paraffin wax phase change materials and phase change material heat sink design approaches. The study used a representative exploration mission with well understood parameters to support the trade. Additional sensitivity studies were performed to ensure the applicability of study results across varying systems and destinations. Results from the study indicate that a water ice PCM heat sink has the potential to decrease the equivalent system mass of the mission s vehicle through a combination of a smaller heat sink and a slight 5% increase in radiator size or the addition of a lightweight heat pump. An evaluation of existing and emerging PCM heat sink technologies indicates that further significant mass savings should be achievable through continued development of those technologies. The largest mass savings may be realized by managing the location of the liquid and the solid in the heat sink to eliminate the melting and freezing pressure of wax and water, respectively, while also accommodating the high structural loads expected on future manned launch vehicles.

Quinn, Gregory↗
NASA NTRS1968

Engines for manned spacecraft.

Apollo propulsion systems design and development emphasizing performance, thrust chamber durability, combustion stability and leakage

Yodzis, C. W.↗