369 Matching Results

Search Results

Advanced search parameters have been applied.

Round Trip to Orbit: Human Spaceflight Alternatives

Description: This special report examines a wide range of potential improvements to the Space Shuttle, explores the future of space transportation for humans, and presents policy options for congressional consideration. It is one of a series of products from abroad assessment of space transportation technologies undertaken by OTA, requested by the Senate Committee on Commerce, Science, and Transportation, and the House Committee on Science, Space, and Technology.
Date: August 1989
Creator: United States. Congress. Office of Technology Assessment.
Partner: UNT Libraries Government Documents Department

Review of U.S. Human Space Flight Plans Committee

Description: This website contains information about the Review of U.S. Human Space Flight Plans Committee including their final report from October 2009. Acourding to their "About" page, "[t]he "Review of United States Human Space Flight Plans" is to examine ongoing and planned National Aeronautics and Space Administration (NASA) development activities, as well as potential alternatives, and present options for advancing a safe, innovative, affordable, and sustainable human space flight program in the years following Space Shuttle retirement."
Date: March 2, 2010
Creator: United States. National Aeronautics and Space Administration. Review of U.S. Human Space Flight Plans Committee.
Partner: UNT Libraries Government Documents Department

The utility of diamond sensors for space flight

Description: Los Alamos National Laboratory has developed diamond sensors with interdigitated electrodes that operate in a photoconducting mode. The specific application for this work was for the Department of Energy`s instruments flown on the Global Positioning System satellites. Sensors have been fabricated and tested for their response to low-energy x-rays. These sensors can be operated to extremely high volumetric radiation doses. We find that the sensors are extremely useful for situations where the surface radiation dose is not excessive, but that this limit is exceeded for the GPS orbit. It is possible that further studies and special detector arrangements or auxiliary heating of the sensor may push this limit to higher values.
Date: March 1996
Creator: Higbie, P. R.; Han, S. S. & Wagner, R. S.
Partner: UNT Libraries Government Documents Department

The Europa Ocean Discovery mission

Description: Since it was first proposed that tidal heating of Europa by Jupiter might lead to liquid water oceans below Europa`s ice cover, there has been speculation over the possible exobiological implications of such an ocean. Liquid water is the essential ingredient for life as it is known, and the existence of a second water ocean in the Solar System would be of paramount importance for seeking the origin and existence of life beyond Earth. The authors present here a Discovery-class mission concept (Europa Ocean Discovery) to determine the existence of a liquid water ocean on Europa and to characterize Europa`s surface structure. The technical goal of the Europa Ocean Discovery mission is to study Europa with an orbiting spacecraft. This goal is challenging but entirely feasible within the Discovery envelope. There are four key challenges: entering Europan orbit, generating power, surviving long enough in the radiation environment to return valuable science, and complete the mission within the Discovery program`s launch vehicle and budget constraints. The authors will present here a viable mission that meets these challenges.
Date: June 1, 1997
Creator: Edwards, B.C.; Chyba, C.F. & Abshire, J.B.
Partner: UNT Libraries Government Documents Department

Acceptability of risk from radiation: Application to human space flight

Description: This one of NASA`s sponsored activities of the NCRP. In 1983, NASA asked NCRP to examine radiation risks in space and to make recommendations about career radiation limits for astronauts (with cancer considered as the principal risk). In conjunction with that effort, NCRP was asked to convene this symposium; objective is to examine the technical, strategic, and philosophical issues pertaining to acceptable risk and radiation in space. Nine papers are included together with panel discussions and a summary. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.
Date: April 30, 1997
Partner: UNT Libraries Government Documents Department

Debris masses and areas inferred from the launch catalog

Description: Debris density and area can be determined as functions of altitude from the debris launch catalog. Those quantities can be used in an algebraic model to predict fragments and intact object density at each altitude. The measured spectrum of debris objects can be used to partition objects into fragments and intact object fractions that are consistent with the catalog and not overly sensitive to the choice of the defining boundary.
Date: January 1, 1997
Creator: Canavan, G. H.
Partner: UNT Libraries Government Documents Department

Debris growth sensitivity to launch and cascade rates

Description: Two-component models provide a good description of debris growth from the outset of launch to the present, predictions of future trends, and assessments of their sensitivity. Launch rate reductions produce less than proportional reductions in debris, for reasons that are discussed. The shift of debris to higher altitudes is assessed quantitatively, although the details of the growth are discussed elsewhere.
Date: October 24, 1996
Creator: Canavan, G. H.
Partner: UNT Libraries Government Documents Department

Solar particle events and their radiation threats

Description: Energetic particles from the Sun have only been studied in detail during the last three decades. The modern record is good, although the number of the largest solar particle events are very few. The nuclides made by solar energetic particles in lunar rocks have been used to extend the record of these particles {approximately} 10{sup 7} years. The modern and ancient records are similar. By combining both sets of data, it has been inferred that solar particle events much larger than the largest events observed during the last four solar cycles are very rare.
Date: March 1998
Creator: Reedy, R. C.
Partner: UNT Libraries Government Documents Department

Space age. Final report

Description: Space age had its world premiere at the large-screen Spaceport Theater at Cape Canaveral/Kennedy Spaceport. The first program was screened for invited guests who, that morning, also witnessed a launch of the Space Shuttle. Since that mission carried the first Japanese astronaut, it was a nice tie-in to the substantial co-production participation of space age by NHK Japan. A special press conference for the series and a twenty-minute preview reel was screened for journalists who were also at the Cape for the shuttle launch. Numerous first-hand newspaper articles were generated. CNN ran part of the preview reel. The first episode in the series, `The Quest for Planet Mars,` then ran twice a day for a week, prior to the Public Broadcasting Service broadcast on an Imax format screen at the Spaceport theater. The program was seen by thousands of visitors. Space age also had a special premier at the National Academy of Sciences in Washington, DC with some 400 special guests, including scientists and government agency representatives.
Date: May 1, 1998
Partner: UNT Libraries Government Documents Department

A study of cylindrical Hall thruster for low power space applications

Description: A 9 cm cylindrical thruster with a ceramic channel exhibited performance comparable to the state-of-the-art Hall thrusters at low and moderate power levels. Significantly, its operation is not accompanied by large amplitude discharge low frequency oscillations. Preliminary experiments on a 2 cm cylindrical thruster suggest the possibility of a high performance micro Hall thruster.
Date: July 27, 2000
Creator: Raitses, Y.; Fisch, N.J.; Ertmer, K.M. & Burlingame, C.A.
Partner: UNT Libraries Government Documents Department

Final Report 94ER75989 [U.S. DOE-FCCSET-Summer Teaching Enhancement Program]

Description: This is the final report for the interagency agreement between the Department of Energy and NASA, 94ER75989, titled U.S. DOE-FCCSET-Summer Teaching Enhancement Program. Our goal to enhance the classroom Instruction in the earth and environmental science programs in the secondary schools of the state of Maryland. The participation of 72 teachers of secondary school students were collaborative partners with the 24 local Maryland School System, the Maryland State Department of Education, the University of Maryland, and the Goddard Space Flight Center. The program enabled these teachers the opportunity to attend a four-week program to enhance the teaching of the earth and environmental sciences in the secondary schools of Maryland. Participants learned how earth systems are studied both from the ground station earth monitoring project and continued it during the school year with their students. Each teacher served as an ambassador for earth science teaching enhancement in their respective school and school system.
Date: November 6, 2001
Partner: UNT Libraries Government Documents Department

Determination and Modeling of Error Densities in Ephemeris Prediction

Description: The authors determined error densities of ephemeris predictions for 14 LEO satellites. The empirical distributions are not inconsistent with the hypothesis of a Gaussian distribution. The growth rate of radial errors are most highly correlated with eccentricity ({vert_bar}r{vert_bar} = 0.63, {alpha} < 0.05). The growth rate of along-track errors is most highly correlated with the decay rate of the semimajor axis ({vert_bar}r{vert_bar} = 0.97; {alpha} < 0.01).
Date: February 7, 1999
Creator: Jones, J.P. & Beckerman, M.
Partner: UNT Libraries Government Documents Department

Equilibrium fluid interface behavior under low- and zero-gravity conditions. II

Description: We describe here recent mathematical results that form the basis of our forthcoming space experiment, developed jointly with Mark Weislogel of NASA Lewis Research Center, which is scheduled for the Glovebox on the Mir 23 / NASA 4 Mission in December 1996. The mathematical basis for the Angular Liquid Bridge is described. The anticipated liquid behavior used in the apparatus is illustrated.
Date: May 1, 1996
Creator: Concus, P. & Finn, R.
Partner: UNT Libraries Government Documents Department

Space in Space: Privacy Needs for Long-Duration Spaceflight

Description: Space exploration is a uniquely human activity. As humans continue to push the limits of exploring the unknown, they have sought knowledge supporting the sustenance of life in outer space. New technologies, advancements in medicine, and rethinking what it means to be a “community” will need to emerge to support life among the stars. Crews traveling beyond the Moon will rely on the development of new technologies to support the technological aspects of their missions as well as their quality of life while away from Earth. Likewise, through advancements in medicine, scientists will need to address remaining questions regarding the effects of long-duration spaceflight on the human body and crew performance. Space explorers must learn to utilize these new technologies and medical advancements while learning to adapt to their new environment in space and as a space community. It is important that researchers address these issues so that human survival beyond Earth is not only achievable but so that life among the stars is worth living and sustaining. This thesis addressed these issues in an attempt to extend the trajectory of space exploration to new horizons.
Date: May 2014
Creator: Aiken, Jo
Partner: UNT Libraries

Thermal Radiative Heat Transfer to Space From a Body Enclosed by a Semitransparent Body

Description: Bumpers were proposed for protecting space radiator systems from penetration by meteoroids. The development of equations to determine the thermal energy dissipation to space by a hot body completely enclosed by a second body is presented. The particular case of heat dissipation from space radiators enclosed within the bumpers is considered, and the criteria for selection of bumper materials for a minimum weight radiator system are discussed. (auth)
Date: May 1, 1960
Creator: Hefner, R. J.
Partner: UNT Libraries Government Documents Department

LISK-BROOM: Clearing near-Earth space debris in 4 years using a 20-kW, 530-nm repetitively pulsed laser

Description: When space debris forced a change of plan for a recent US Space Shuttle mission, it finally reached the point of broad awareness. Almost a million pieces of debris have been generated by 35 years of spaceflight, and now threaten some long-term space missions. This problem can best a be solved by causing space debris items to re-enter and burn up in the atmosphere on a computed trajectory. Illumination of the objects by a repetitively-pulsed laser will easily produce a laser-ablation jet providing the impulse to de-orbit the object. For reasons we will discuss, we propose the use of a ground-based laser system, atmospheric-turbulence compensating beam director, computer and high resolution detection system to solve this problem. A laser of just 2OkW average power and state-of-the-art detection capabilities could clear near-Earth space below 1100km altitude of all space debris larger than 1 cm but less massive than 100kg in about 4 years. The LISK-BROOM laser would be located near the Equator above 5km elevation [e.g., the Uhuru site on Kilimanjarol, minimizing turbulence correction and absorption of the 530-nm wavelength laser beam. LISK-BROOM is a special case of Laser Impulse Space Propulsion (LISP), by which objects are propelled in space by the ablation jet due to a distant laser. We will also discuss active beam phase error correction during passage through the atmosphere and the object detection system which are necessary.
Date: October 1, 1994
Creator: Phipps, C. R. & Michaelis, M. M.
Partner: UNT Libraries Government Documents Department