Partner
Oklahoma Historical Society
1,004
UNT Libraries Government Documents Department
148
UNT Libraries
122
Abilene Library Consortium
66
Abilene Public Library
65
Sterling Municipal Library
56
Denton Public Library
24
Hopkins County Genealogical Society
23
University of Texas at El Paso
21
Cuero Public Library
20
118 More
Collection
Oklahoma Digital Newspaper Program
1,030
Texas Digital Newspaper Program
836
Tocker Foundation Grant
229
Chickasha Newspaper Collection
203
The Oklahoma City Times
198
Abilene Library Consortium
144
Altus Times-Democrat
104
Sapulpa Herald
100
Sapulpa Area Newspaper Collection
100
Office of Scientific & Technical Information Technical Reports
87
227 More
Country
Decade
Month
Language
2,027 Matching Results
Results open in a new window/tab. Unexpected Results? Search the Catalog Instead.
Results:
1 - 24 of
2,027
next
The Mars Hopper: a radioisotope powered, impulse driven, long-range, long-lived mobile platform for exploration of Mars
Planetary exploration mission requirements are becoming more demanding. Due to the increasing cost, the missions that provide mobile platforms that can acquire data at multiple locations are becoming more attractive. Wheeled vehicles such as the MER rovers have proven extremely capable but have very limited range and cannot traverse rugged terrain. Flying vehicles such as balloons and airplanes have been proposed but are problematic due to the very thin atmospheric pressure and the strong, dusty winds present on Mars. The Center for Space Nuclear Research has designed an instrumented platform that can acquire detailed data at hundreds of locations during its lifetime - a Mars Hopper. The Mars Hopper concept utilizes energy from radioisotopic decay in a manner different from any existing radioisotopic power sources—as a thermal capacitor. By accumulating the heat from radioisotopic decay for long periods, the power of the source can be dramatically increased for short periods. The platform will be able to "hop" from one location to the next every 5-7 days with a separation of 5-10 km per hop. Preliminary designs show a platform that weighs around 52 kgs unfueled which is the condition at deployment. Consequently, several platforms may be deployed on a single …
Date:
February 1, 2011
Creator:
Howe, Steven D.; O'Brien, Robert C.; Taitano, William; Crawford, Doug; Jerred, Nathan; Cooley, Spencer et al.
Object Type:
Article
System:
The UNT Digital Library
Advanced hybrid nuclear propulsion Mars mission performance enhancement
Nuclear electric propulsion (NEP), compared with chemical and nuclear thermal propulsion (NTP), can effectively deliver the same mass to Mars using much less propellant, consequently requiring less mass delivered to Earth orbit. The lower thrust of NEP requires a spiral trajectory near planetary bodies, which significantly increases the travel time. Although the total travel time is long, the portion of the flight time spent during interplanetary transfer is shorter, because the vehicle is thrusting for much longer periods of time. This has led to the supposition that NEP, although very attractive for cargo missions, is not suitable for piloted missions to Mars. However, with the application of a hybrid approach to propulsion, the benefits of NEP can be utilized while drastically reducing the overall travel time required. Development of a dual-mode system, which utilizes high-thrust NTP to propel the spacecraft from the planetary gravitational influence and low-thrust NEP to accelerate in interplanetary space, eliminates the spiral trajectory and results in a much faster transit time than could be obtained by either NEP or NTP alone. This results in a mission profile with a lower initial mass in low Earth orbit. In addition, the propulsion system would have the capability to …
Date:
February 1, 1992
Creator:
Dagle, J. E.; Noffsinger, K. E. & Segna, D. R.
Object Type:
Article
System:
The UNT Digital Library
Advanced hybrid nuclear propulsion Mars mission performance enhancement
Nuclear electric propulsion (NEP), compared with chemical and nuclear thermal propulsion (NTP), can effectively deliver the same mass to Mars using much less propellant, consequently requiring less mass delivered to Earth orbit. The lower thrust of NEP requires a spiral trajectory near planetary bodies, which significantly increases the travel time. Although the total travel time is long, the portion of the flight time spent during interplanetary transfer is shorter, because the vehicle is thrusting for much longer periods of time. This has led to the supposition that NEP, although very attractive for cargo missions, is not suitable for piloted missions to Mars. However, with the application of a hybrid approach to propulsion, the benefits of NEP can be utilized while drastically reducing the overall travel time required. Development of a dual-mode system, which utilizes high-thrust NTP to propel the spacecraft from the planetary gravitational influence and low-thrust NEP to accelerate in interplanetary space, eliminates the spiral trajectory and results in a much faster transit time than could be obtained by either NEP or NTP alone. This results in a mission profile with a lower initial mass in low Earth orbit. In addition, the propulsion system would have the capability to …
Date:
February 1, 1992
Creator:
Dagle, J. E.; Noffsinger, K. E. & Segna, D. R.
Object Type:
Article
System:
The UNT Digital Library
Feasibility of Ground Testing a Moon and Mars Surface Power Reactor in EBR-II
Ground testing of a surface fission power system would be necessary to verify the design and validate reactor performance to support safe and sustained human exploration of the Moon and Mars. The Idaho National Laboratory (INL) has several facilities that could be adapted to support a ground test. This paper focuses on the feasibility of ground testing at the Experimental Breeder Reactor II (EBR-II) facility and using other INL existing infrastructure to support such a test. This brief study concludes that the INL EBR-II facility and supporting infrastructure are a viable option for ground testing the surface power system. It provides features and attributes that offer advantages to locating and performing ground testing at this site, and it could support the National Aeronautics and Space Administration schedules for human exploration of the Moon. This study used the initial concept examined by the U.S. Department of Energy Inter-laboratory Design and Analysis Support Team for surface power, a lowtemperature, liquid-metal, three-loop Brayton power system. With some facility modification, the EBR-II can safely house a test chamber and perform long-term testing of the space reactor power system. The INL infrastructure is available to receive and provide bonded storage for special nuclear materials. Facilities …
Date:
February 1, 2006
Creator:
Morton, Sheryl; Baily, Carl; Hill, Tom & Werner, Jim
Object Type:
Article
System:
The UNT Digital Library
Science Priorities for Mars Sample Return
None
Date:
February 11, 2008
Creator:
Borg, L.; Des Marais, D. & Beaty, D.
Object Type:
Report
System:
The UNT Digital Library
A Flow-Channel Analysis for the Mars Hopper
The Mars Hopper is an exploratory vehicle designed to fly on Mars using carbon dioxide from the Martian atmosphere as a rocket propellant. The propellent gasses are thermally heated while traversing a radioisotope ther- mal rocket (RTR) engine’s core. This core is comprised of a radioisotope surrounded by a heat capacitive material interspersed with tubes for the propellant to travel through. These tubes, or flow channels, can be manu- factured in various cross-sectional shapes such as a special four-point star or the traditional circle. Analytical heat transfer and computational fluid dynamics (CFD) anal- yses were performed using flow channels with either a circle or a star cross- sectional shape. The nominal total inlet pressure was specified at 2,805,000 Pa; and the outlet pressure was set to 2,785,000 Pa. The CO2 inlet tem- perature was 300 K; and the channel wall was 1200 K. The steady-state CFD simulations computed the smooth-walled star shape’s outlet temper- ature to be 959 K on the finest mesh. The smooth-walled circle’s outlet temperature was 902 K. A circle with a surface roughness specification at 0.01 mm gave 946 K and at 0.1 mm yielded 989 K. The The effects of a slightly varied inlet pressure …
Date:
February 1, 2013
Creator:
Cooley, W. Spencer
Object Type:
Book
System:
The UNT Digital Library
Development of the Variable Atmosphere Testing Facility for Blow-Down Analysis of the Mars Hopper Prototype
Recent developments at the Center for Space Nuclear Research (CSNR) on a Martian exploration probe have lead to the assembly of a multi-functional variable atmosphere testing facility (VATF). The VATF has been assembled to perform transient blow-down analysis of a radioisotope thermal rocket (RTR) concept that has been proposed for the Mars Hopper; a long-lived, long-ranged mobile platform for the Martian surface. This study discusses the current state of the VATF as well as recent blow-down testing performed on a laboratory-scale prototype of the Mars Hopper. The VATF allows for the simulation of Mars ambient conditions within the pressure vessel as well as to safely perform blow-down tests through the prototype using CO2 gas; the proposed propellant for the Mars Hopper. Empirical data gathered will lead to a better understanding of CO2 behavior and will provide validation of simulation models. Additionally, the potential of the VATF to test varying propulsion system designs has been recognized. In addition to being able to simulate varying atmospheres and blow-down gases for the RTR, it can be fitted to perform high temperature hydrogen testing of fuel elements for nuclear thermal propulsion.
Date:
February 1, 2013
Creator:
Jerred, Nathan D.; O'Brien, Robert C.; Howe, Steven D. & O'Brien, James E.
Object Type:
Article
System:
The UNT Digital Library
Space Exploration: Overview of President Bush’s New Exploration Initiative for NASA, and Key Issues for Congress
This article discusses the new goals set for the National Aeronautics and Space Administration and asks important questions to congress. Updated February 17, 2004.
Date:
February 17, 2004
Creator:
Smith, Marcia S.
Object Type:
Report
System:
The UNT Digital Library
Thermal-hydraulics Analysis of a Radioisotope-powered Mars Hopper Propulsion System
Thermal-hydraulics analyses results produced using a combined suite of computational design and analysis codes are presented for the preliminary design of a concept Radioisotope Thermal Rocket (RTR) propulsion system. Modeling of the transient heating and steady state temperatures of the system is presented. Simulation results for propellant blow down during impulsive operation are also presented. The results from this study validate the feasibility of a practical thermally capacitive RTR propulsion system.
Date:
February 1, 2011
Creator:
O'Brien, Robert C.; Klein, Andrew C.; Taitano, William T.; Gibson, Justice; Myers, Brian & Howe, Steven D.
Object Type:
Article
System:
The UNT Digital Library
Development of a propulsion system and component test facility for advanced radioisotope powered Mars Hopper platforms
Verification and validation of design and modeling activities for radioisotope powered Mars Hopper platforms undertaken at the Center for Space Nuclear Research is essential for proof of concept. Previous research at the center has driven the selection of advanced material combinations; some of which require specialized handling capabilities. The development of a closed and contained test facility to forward this research is discussed within this paper.
Date:
February 1, 2011
Creator:
O'Brien, Robert C.; Jerred, Nathan D. & Howe, Steven D.
Object Type:
Article
System:
The UNT Digital Library
Small Body Exploration Technologies as Precursors for Interstellar Robotics
The scientific activities undertaken to explore our Solar System will be the same as required someday at other stars. The systematic exploration of primitive small bodies throughout our Solar System requires new technologies for autonomous robotic spacecraft. These diverse celestial bodies contain clues to the early stages of the Solar System's evolution as well as information about the origin and transport of water-rich and organic material, the essential building blocks for life. They will be among the first objects studied at distant star systems. The technologies developed to address small body and outer planet exploration will form much of the technical basis for designing interstellar robotic explorers. The Small Bodies Assessment Group, which reports to NASA, initiated a Technology Forum in 2011 that brought together scientists and technologists to discuss the needs and opportunities for small body robotic exploration in the Solar System. Presentations and discussions occurred in the areas of mission and spacecraft design, electric power, propulsion, avionics, communications, autonomous navigation, remote sensing and surface instruments, sampling, intelligent event recognition, and command and sequencing software. In this paper, the major technology themes from the Technology Forum are reviewed, and suggestions are made for developments that will have the largest …
Date:
February 15, 2012
Creator:
Noble, Robert & Sykes, Mark V.
Object Type:
Article
System:
The UNT Digital Library
The Embudito Mission: A Case Study of the Systematics of Autonomous Ground Mobile Robots
Ground mobile robots are much in the mind of defense planners at this time, being considered for a significant variety of missions with a diversity ranging from logistics supply to reconnaissance and surveillance. While there has been a very large amount of basic research funded in the last quarter century devoted to mobile robots and their supporting component technologies, little of this science base has been fully developed and deployed--notable exceptions being NASA's Mars rover and several terrestrial derivatives. The material in this paper was developed as a first exemplary step in the development of a more systematic approach to the R and D of ground mobile robots.
Date:
February 1, 2001
Creator:
EICKER,PATRICK J.
Object Type:
Report
System:
The UNT Digital Library
Laboratory Directed Research and Development Program FY98
The Ernest Orlando Lawrence Berkeley National Laboratory (LBNL or Berkeley Lab) Laboratory Directed Research and Development Program FY 1998 report is compiled from annual reports submitted by principal investigators following the close of the fiscal year. This report describes the supported projects and summarizes their accomplishments. It constitutes a part of the Laboratory Directed Research and Development (LDRD) program planning and documentation process that includes an annual planning cycle, projection selection, implementation, and review. The LBNL LDRD program is a critical tool for directing the Laboratory's forefront scientific research capabilities toward vital, excellent, and emerging scientific challenges. The program provides the resources for LBNL scientists to make rapid and significant contributions to critical national science and technology problems. The LDRD program also advances LBNL's core competencies, foundations, and scientific capability, and permits exploration of exciting new opportunities. All projects are work in forefront areas of science and technology. Areas eligible for support include the following: Advanced study of hypotheses, concepts, or innovative approaches to scientific or technical problems; Experiments and analyses directed toward ''proof of principle'' or early determination of the utility of new scientific ideas, technical concepts, or devices; and Conception and preliminary technical analyses of experimental facilities or …
Date:
February 5, 1999
Creator:
Hansen, T. & Chartock, M.
Object Type:
Report
System:
The UNT Digital Library
[National Aeronautics and Space Administration: Overview, FY2007 Budget in Brief, and Key Issues for Congress, February 27, 2007]
This report discusses the budget of the fiscal year of 2007 and the requests of the National Aeronautics and Space Administration. Updated February 27, 2007.
Date:
February 27, 2007
Creator:
Morgan, Daniel & Behrens, Carl E.
Object Type:
Report
System:
The UNT Digital Library
National Aeronautics and Space Administration: Overview, FY2009 Budget, and Issues for Congress
This report discusses the budget of the fiscal year of 2009 and the requests of the National Aeronautics and Space Administration.
Date:
February 26, 2008
Creator:
Morgan, Daniel & Behrens, Carl E.
Object Type:
Report
System:
The UNT Digital Library
Planning For Multiple NASA Missions With Use Of Enabling Radioisotope Power
Since the early 1960’s the Department of Energy (DOE) and its predecessor agencies have provided radioisotope power systems (RPS) to NASA as an enabling technology for deep space and various planetary missions. They provide reliable power in situations where solar and/or battery power sources are either untenable or would place an undue mass burden on the mission. In the modern era of the past twenty years there has been no time that multiple missions have been considered for launching from Kennedy Space Center (KSC) during the same year. The closest proximity of missions that involved radioisotope power systems would be that of Galileo (October 1989) and Ulysses (October 1990). The closest that involved radioisotope heater units would be the small rovers Spirit and Opportunity (May and July 2003) used in the Mars Exploration Rovers (MER) mission. It can be argued that the rovers sent to Mars in 2003 were essentially a special case since they staged in the same facility and used a pair of small launch vehicles (Delta II). This paper examines constraints on the frequency of use of radioisotope power systems with regard to launching them from Kennedy Space Center using currently available launch vehicles. This knowledge may …
Date:
February 1, 2013
Creator:
Johnson, S.G.; Lively, K.L. & Dwight, C.C.
Object Type:
Article
System:
The UNT Digital Library
SP-100 planetary mission/system preliminary design study. Final report, technical information report
This report contains a discussion on many aspects of a nuclear electric propulsion planetary science mission and spacecraft using the proposed SP-100 nuclear power subsystem. A review of the science rationale for such missions is included. A summary of eleven nuclear electric propulsion planetary missions is presented. A conceptual science payload, mission design, and spacecraft design is included for the Saturn Ring Rendezvous mission. Spacecraft and mission costs have been estimated for two potential sequences of nuclear electric propulsion planetary missions. The integration issues and requirements on the proposed SP-100 power subsystems are identified.
Date:
February 1, 1986
Creator:
Jones, R. M.
Object Type:
Report
System:
The UNT Digital Library
Prospecting for lunar ice using a multi-rover cooperative team
A multi-rover cooperative team or swarm developed by Sandia National Laboratories is described, including various control methodologies that have been implemented to date. How the swarm's capabilities could be applied to a lunar ice prospecting mission is briefly explored. Some of the specific major engineering issues that must be addressed to successfully implement the swarm approach to a lunar surface mission are outlined, and potential solutions are proposed.
Date:
February 11, 2000
Creator:
Klarer, Paul R.; Feddema, John T. & Lewis, Christopher L.
Object Type:
Article
System:
The UNT Digital Library
Evaporites as a source for oil
Organic matter, present in some sediments, acts as the source for hydrocarbons and has been studied at great length, but organic-rich sediments from hypersaline environments are just beginning to be understood. Many types of organic matter from such restricted environments have been identified, and in this study their maturation pathways and products are being explored. By collecting biologically-identified organic matter produced within modern evaporative environments from a number of different marine and nonmarine settings and carrying out detailed geochemical examination of samples we are gradually beginning to understand these materials. The organic samples collected were from evaporative marine, sabkha, and lacustrine deposits, and have been subjected to two types of artificial maturation, hydrous and confined pyrolysis, over a fairly wide range of temperatures (1500 to 350[degrees]C). The biomarker products of these treatments are being analyzed and followed in great detail. Analyses of saturate and aromatic hydrocarbons as well as sulfur compounds in the original and the matured samples provide a comprehensive view of the biomarker assemblages associated with these different depositional environments at different stages of maturity. Infrared spectroscopy and Rock Eval pyrolysis of both the isolated kerogens from both the original and pyrolyzed samples has permitted us to clearly …
Date:
February 1, 1993
Creator:
Schreiber, B.C.; Benalihioulhaj, S. (Queens Coll., Flushing, NY (United States). Dept. of Geology) & Philp, R.P. (Oklahoma Univ., Norman, OK (United States). School of Geology and Geophysics)
Object Type:
Report
System:
The UNT Digital Library
Evaporites as a source for oil. Progress report, November 15, 1988--November 15, 1992
Organic matter, present in some sediments, acts as the source for hydrocarbons and has been studied at great length, but organic-rich sediments from hypersaline environments are just beginning to be understood. Many types of organic matter from such restricted environments have been identified, and in this study their maturation pathways and products are being explored. By collecting biologically-identified organic matter produced within modern evaporative environments from a number of different marine and nonmarine settings and carrying out detailed geochemical examination of samples we are gradually beginning to understand these materials. The organic samples collected were from evaporative marine, sabkha, and lacustrine deposits, and have been subjected to two types of artificial maturation, hydrous and confined pyrolysis, over a fairly wide range of temperatures (1500 to 350{degrees}C). The biomarker products of these treatments are being analyzed and followed in great detail. Analyses of saturate and aromatic hydrocarbons as well as sulfur compounds in the original and the matured samples provide a comprehensive view of the biomarker assemblages associated with these different depositional environments at different stages of maturity. Infrared spectroscopy and Rock Eval pyrolysis of both the isolated kerogens from both the original and pyrolyzed samples has permitted us to clearly …
Date:
February 1, 1993
Creator:
Schreiber, B. C.; Benalihioulhaj, S. & Philp, R. P.
Object Type:
Report
System:
The UNT Digital Library
An alternative strategy for low specific power reactors to power interplanetary spacecraft, based on exploiting lasers and lunar resources
A key requirement setting the minimum electric propulsion performance (specific power ..cap alpha../sub e/ = kW/sub e//kg) for manned missions to Mars is the maximum allowable radiation dose to the crew during the long transits between Earth and Mars. Penetrating galactic cosmic rays and secondary neutron showers give about 0.1-rem/day dose, which only massive shielding (e.g., a meter of concrete) can reduce significantly. With a humane allowance for cabin space, the shielding mass becomes so large that it prohibitively escalates the propellant consumption required for reasonable trip times. This paper covers various proposed methods for using reactor power to propel spacecraft. 7 refs., 6 figs., 1 tab.
Date:
February 2, 1989
Creator:
Logan, B. G.
Object Type:
Report
System:
The UNT Digital Library
Views of the solar system
Views of the Solar System has been created as an educational tour of the solar system. It contains images and information about the Sun, planets, moons, asteroids and comets found within the solar system. The image processing for many of the images was done by the author. This tour uses hypertext to allow space travel by simply clicking on a desired planet. This causes information and images about the planet to appear on screen. While on a planet page, hyperlinks travel to pages about the moons and other relevant available resources. Unusual terms are linked to and defined in the Glossary page. Statistical information of the planets and satellites can be browsed through lists sorted by name, radius and distance. History of Space Exploration contains information about rocket history, early astronauts, space missions, spacecraft and detailed chronology tables of space exploration. The Table of Contents page has links to all of the various pages within Views Of the Solar System.
Date:
February 1, 1995
Creator:
Hamilton, C.
Object Type:
Report
System:
The UNT Digital Library
Final Report - Assessment of Testing Options for the NTR at the INL
One of the main technologies that can be developed to dramatically enhance the human exploration of space is the nuclear thermal rocket (NTR). Several studies over the past thirty years have shown that the NTR can reduce the cost of a lunar outpost, reduce the risk of a human mission to Mars, enable fast transits for most missions throughout the solar system, and reduce the cost and time for robotic probes to deep space. Three separate committees of the National Research Council of the National Academy of Sciences have recommended that NASA develop the NTR. One of the primary issues in development of the NTR is the ability to verify a flight ready unit. Three main methods can be used to validate safe operation of a NTR: 1) Full power, full duration test in an above ground facility that scrubs the rocket exhaust clean of any fission products; 2) Full power , full duration test using the Subsurface Active Filtering of Exhaust (SAFE) technique to capture the exhaust in subsurface strata; 3) Test of the reactor fuel at temperature and power density in a driver reactor with subsequent first test of the fully integrated NTR in space. The first method, …
Date:
February 1, 2013
Creator:
Howe, Steven D; McLing, Travis L; McCurry, Michael & Plummer, Mitchell A
Object Type:
Report
System:
The UNT Digital Library
NASA: Assessments of Selected Large-Scale Projects
A letter report issued by the Government Accountability Office with an abstract that begins "The National Aeronautics and Space Administration (NASA) plans to invest billions in the coming years in science and exploration space fl ight initiatives. The scientifi c and technical complexities inherent in NASA's mission create great challenges in managing its projects and controlling costs. In the past, NASA has had diffi culty meeting cost, schedule, and performance objectives for many of its projects. The need to effectively manage projects will gain even more importance as NASA seeks to manage its wide-ranging portfolio in an increasingly constrained fi scal environment. This report provides an independent assessment of selected NASA projects. In conducting this work, GAO compared projects against best practice criteria for system development including attainment of knowledge on technologies and design. GAO also identifi ed other programmatic challenges that were contributing factors in cost and schedule growth of the projects reviewed. The projects assessed are considered major acquisitions by NASA--each with a life-cycle cost of over $250 million. No recommendations are provided in this report; however, GAO has reported extensively and made recommendations on NASA acquisition management in the past. GAO has designated NASA's acquisition management as …
Date:
February 1, 2010
Creator:
United States. Government Accountability Office.
Object Type:
Report
System:
The UNT Digital Library