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Exploration of the Planets: A History, A Prospect, and Some Issues
This report discusses the history and future of planetary exploration programs by the U.S. and the Soviet Union. Topics covered are motivations for planetary exploration, unmanned missions sent to Mars and Venus by the U.S. and Soviet Union, plans for manned missions to planets such as Mars, technical needs and costs for planetary space missions, and long-term plans and ideas.
Date:
December 15, 1969
Creator:
Devoe, Barbara M. & Sheldon, Charles S., II
Object Type:
Report
System:
The UNT Digital Library
Space Exploration: Overview of President Bush's "Vision for Space Exploration," and Key Issues for Congress
Report detailing the vision for space exploration, including budget changes for NASA, public reaction, and more.
Date:
March 15, 2005
Creator:
Smith, Marcia S.
Object Type:
Report
System:
The UNT Digital Library
Basalt weathering rates on Earth and the duration of liquid water on the plains of Gusev Crater, Mars
Where Martian rocks have been exposed to liquid water, chemistry versus depth profiles could elucidate both Martian climate history and potential for life. The persistence of primary minerals in weathered profiles constrains the exposure time to liquid water: on Earth, mineral persistence times range from {approx}10 ka (olivine) to {approx}250 ka (glass) to {approx}1Ma (pyroxene) to {approx}5Ma (plagioclase). Such persistence times suggest mineral persistence minima on Mars. However, Martian solutions may have been more acidic than on Earth. Relative mineral weathering rates observed for basalt in Svalbard (Norway) and Costa Rica demonstrate that laboratory pH trends can be used to estimate exposure to liquid water both qualitatively (mineral absence or presence) and quantitatively (using reactive transport models). Qualitatively, if the Martian solution pH > {approx}2, glass should persist longer than olivine; therefore, persistence of glass may be a pH-indicator. With evidence for the pH of weathering, the reactive transport code CrunchFlow can quantitatively calculate the minimum duration of exposure to liquid water consistent with a chemical profile. For the profile measured on the surface of Humphrey in Gusev Crater, the minimum exposure time is 22 ka. If correct, this estimate is consistent with short-term, episodic alteration accompanied by ongoing surface …
Date:
March 15, 2008
Creator:
Steefel, Carl; Hausrath, E. M.; Navarre-Sitchler, A. K.; Sak, P. B.; Steefel, C. & Brantley, S. L.
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
Safety questions relevant to nuclear thermal propulsion
Nuclear propulsion is necessary for successful Mars exploration to enhance crew safety and reduce mission costs. Safety concerns are considered by some to be an implements to the use of nuclear thermal rockets for these missions. Therefore, an assessment was made of the various types of possible accident conditions that might occur and whether design or operational solutions exist. With the previous work on the NERVA nuclear rocket, most of the issues have been addressed in some detail. Thus, a large data base exist to use in an agreement. The assessment includes evaluating both ground, launch, space operations and disposal conditions. The conclusion is that design and operational solutions do exist for the safe use of nuclear thermal rockets and that both the environment and crews be protected against harmful radiation. Further, it is concluded that the use of nuclear thermal propulsion will reduce the radiation and mission risks to the Mars crews.
Date:
October 15, 1991
Creator:
Buden, D.
Object Type:
Article
System:
The UNT Digital Library
Safety questions relevant to nuclear thermal propulsion
Nuclear propulsion is necessary for successful Mars exploration to enhance crew safety and reduce mission costs. Safety concerns are considered by some to be an implements to the use of nuclear thermal rockets for these missions. Therefore, an assessment was made of the various types of possible accident conditions that might occur and whether design or operational solutions exist. With the previous work on the NERVA nuclear rocket, most of the issues have been addressed in some detail. Thus, a large data base exist to use in an agreement. The assessment includes evaluating both ground, launch, space operations and disposal conditions. The conclusion is that design and operational solutions do exist for the safe use of nuclear thermal rockets and that both the environment and crews be protected against harmful radiation. Further, it is concluded that the use of nuclear thermal propulsion will reduce the radiation and mission risks to the Mars crews.
Date:
October 15, 1991
Creator:
Buden, D.
Object Type:
Article
System:
The UNT Digital Library
Cooperative Robot Teams Applied to the Site Preparation Task
Prior to human missions to Mars, infrastructures on Mars that support human survival must be prepared. robotic teams can assist in these advance preparations in a number of ways. This paper addresses one of these advance robotic team tasks--the site preparation task--by proposing a control structure that allows robot teams to cooperatively solve this aspect of infrastructure preparation. A key question in this context is determining how robots should make decisions on which aspect of the site preparation t6ask to address throughout the mission, especially while operating in rough terrains. This paper describes a control approach to solving this problem that is based upon the ALLIANCE architecture, combined with performance-based rough terrain navigation that addresses path planning and control of mobile robots in rough terrain environments. They present the site preparation task and the proposed cooperative control approach, followed by some of the results of the initial testing of various aspects of the system.
Date:
June 15, 2001
Creator:
Parker, LE
Object Type:
Article
System:
The UNT Digital Library
Measurements of Materials Shielding Properties with 1 GeV/nuc56Fe
The design of future spacecraft such as the Crew ExplorationVehicle must take into account the radiation shielding properties of boththe structural components as well as dedicated shielding materials. Sincemodest depths of shielding stop the vast majority of Solar EnergeticParticles (SEP), the greater challenge is posed by the need to shieldcrew from the Galactic Cosmic Rays (GCR), which include highly-chargedand highly-energetic particles. Here, we report on results from testsperformed with beams of 1 GeV/nuc 56Fe at the Brookhaven NationalLaboratory. A wide variety of targets, both elemental and composite, wereplaced in the particle beams, and the spectra of particles emerging fromthe targets were measured using a stack of silicon detectors. Results arepresented primarily in terms of dose reduction per g cm-2 of targetmaterial, and support the conclusions of an earlier calculation by Wilsonet al. showing that performance improves as the shield's mass numberdecreases, with hydrogen being by far the most effective. The data alsoshow that, as depth increases, the incremental benefit of addingshielding decreases, particularlyfor aluminum and other elements withhigher atomic mass numbers.
Date:
May 15, 2006
Creator:
Zeitlin, Cary; Guetersloh, Stephen B.; Heilbronn, Lawrence H. & Miller, Jack
Object Type:
Article
System:
The UNT Digital Library
NASA: Briefing on National Aeronautics and Space Administration's Programs and Associated Activities
Correspondence issued by the Government Accountability Office with an abstract that begins "The National Aeronautics and Space Act of 1958, as amended, established the National Aeronautics and Space Administration (NASA) as the civilian agency that exercises control over U.S. aeronautical and space activities and seeks and encourages the fullest commercial use of space. NASA's activities span a broad range of complex and technical endeavors, from investigating the composition, evaluation, and resources of Mars; to working with international partners to complete and operate the International Space Station; to providing satellite and aircraft observations of Earth for scientific and weather forecasting; to developing new technologies designed to improve air flight safety. The agency currently engages in these endeavors against a backdrop of growing national government fiscal imbalance and budget deficits that are straining all federal agencies' resources. Although NASA's budget represents less than 2 percent of the federal government's discretionary budget, the agency is increasingly being asked to expand its portfolio to support important scientific missions, including the study of climate change. Therefore, it is important that these resources be managed as effectively and efficiently as possible. The National Aeronautics and Space Administration Authorization Act of 2008 (Pub. L. No. 110-422)--directed us …
Date:
October 15, 2009
Creator:
United States. Government Accountability Office.
Object Type:
Text
System:
The UNT Digital Library
NASA: Assessments of Selected Large-Scale Projects
Other written product issued by the Government Accountability Office with an abstract that begins "The National Aeronautics and Space Administration's (NASA) total portfolio of major projects saw cost and schedule growth that remains low compared to GAO's first review of the portfolio. Some projects in this year's portfolio launched within their cost and schedule baselines; however, several others are undergoing replans, which could temper the portfolio's positive performance. For example, the Mars Atmosphere and Volatile EvolutioN project launched on time and cost about $35 million less than its baseline estimate, but NASA officials are reporting that issues with the Ice, Cloud, and Land Elevation Satellite-2 project's primary instrument are driving costs to exceed the original baseline by at least 15 percent, and that the project will miss its committed launch date."
Date:
April 15, 2014
Creator:
United States. Government Accountability Office.
Object Type:
Text
System:
The UNT Digital Library
Information Security: NASA Needs to Remedy Vulnerabilities in Key Networks
A letter report issued by the Government Accountability Office with an abstract that begins "The National Aeronautics and Space Administration (NASA) relies extensively on information systems and networks to pioneer space exploration, scientific discovery, and aeronautics research. Many of these systems and networks are interconnected through the Internet, and may be targeted by evolving and growing cyber threats from a variety of sources. GAO was directed to (1) determine whether NASA has implemented appropriate controls to protect the confidentiality, integrity, and availability of the information and systems used to support NASA's mission directorates and (2) assess NASA's vulnerabilities in the context of prior incidents and corrective actions. To do this, GAO examined network and system controls in place at three centers; analyzed agency information security policies, plans, and reports; and interviewed agency officials."
Date:
October 15, 2009
Creator:
United States. Government Accountability Office.
Object Type:
Report
System:
The UNT Digital Library
The Wynnewood Gazette (Wynnewood, Okla.), Vol. 105, No. 33, Ed. 1 Thursday, November 15, 2007
Weekly newspaper from Wynnewood, Oklahoma that includes local, state, and national news along with advertising.
Date:
November 15, 2007
Creator:
unknown
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Research and Development Funding: Fiscal Year 2002
None
Date:
May 15, 2001
Creator:
Moteff, John D.
Object Type:
Report
System:
The UNT Digital Library
Commerce, Justice, Science, and Related Agencies: FY2014 Appropriations
This report will track and describe actions taken by the Administration and Congress to provide FY2014 appropriations for Commerce, Justice, and Science (CJS) accounts. It also provides an overview of FY2013 appropriations for agencies and bureaus funded as a part of the annual appropriation for CJS.
Date:
April 15, 2014
Creator:
James, Nathan; Williams, Jennifer D. & Sargent, John F., Jr.
Object Type:
Report
System:
The UNT Digital Library
Crosby County News (Ralls, Tex.), Vol. 129, No. 2, Ed. 1 Friday, January 15, 2016
Weekly newspaper from Ralls, Texas that includes local, state, and national news along with advertising.
Date:
January 15, 2016
Creator:
unknown
Object Type:
Newspaper
System:
The Portal to Texas History
Superpressure Stratospheric Vehicle
Our need for wide-band global communications, earth imaging and sensing, atmospheric measurements and military reconnaissance is extensive, but growing dependence on space-based systems raises concerns about vulnerability. Military commanders require space assets that are more accessible and under local control. As a result, a robust and low cost access to space-like capability has become a national priority. Free floating buoyant vehicles in the middle stratosphere can provide the kind of cost effective access to space-like capability needed for a variety of missions. These vehicles are inexpensive, invisible, and easily launched. Developments in payload electronics, atmospheric modeling, and materials combined with improving communications and navigation infrastructure are making balloon-borne concepts more attractive. The important milestone accomplished by this project was the planned test flight over the continental United States. This document is specifically intended to review the technology development and preparations leading up to the test flight. Although the test flight experienced a payload failure just before entering its assent altitude, significant data were gathered. The results of the test flight are presented here. Important factors included in this report include quality assurance testing of the balloon, payload definition and characteristics, systems integration, preflight testing procedures, range operations, data collection, and …
Date:
September 15, 1990
Creator:
Chocol, C.; Robinson, W. & Epley, L.
Object Type:
Report
System:
The UNT Digital Library
Brownwood Bulletin (Brownwood, Tex.), Vol. 65, No. 287, Ed. 1 Wednesday, September 15, 1965
Daily newspaper from Brownwood, Texas that includes local, state, and national news along with advertising.
Date:
September 15, 1965
Creator:
Gage, Larry
Object Type:
Newspaper
System:
The Portal to Texas History
Altus Times (Altus, Okla.), Vol. 65, No. 169, Ed. 1 Wednesday, July 15, 1987
Daily newspaper from Altus, Oklahoma that includes local, state, and national news along with advertising.
Date:
July 15, 1987
Creator:
unknown
Object Type:
Newspaper
System:
The Gateway to Oklahoma History
Federal Research and Development Funding: FY2005
None
Date:
October 15, 2004
Creator:
Davey, Michael E.
Object Type:
Report
System:
The UNT Digital Library
Nuclear shuttle system definition study. Phase III. Final review
None
Date:
April 15, 1971
Creator:
Littman, T.M.
Object Type:
Report
System:
The UNT Digital Library
Exploring the geophysical signatures of microbial processes in the earth
AGU Chapman Conference on Biogeophysics; Portland, Maine, 13-16 October 2008; Geophysical methods have the potential to detect and characterize microbial growth and activity in subsurface environments over different spatial and temporal scales. Recognition of this potential has resulted in the development of a new subdiscipline in geophysics called 'biogeophysics,' a rapidly evolving Earth science discipline that integrates environmental microbiology, geomicrobiology, biogeochemistry, and geophysics to investigate interactions that occur between the biosphere (microorganisms and their products) and the geosphere. Biogeophysics research performed over the past decade has confirmed the potential for geophysical techniques to detect microbes, microbial growth/biofilm formation, and microbe-mineral interactions. The unique characteristics of geophysical data sets (e.g., noninvasive data acquisition, spatially continuous properties retrieved) present opportunities to explore geomicrobial processes outside of the laboratory, at unique spatial scales unachievable with microbiological techniques, and possibly in remote environments such as the deep ocean. In response to this opportunity, AGU hosted a Chapman Conference with a mission to bring together geophysicists, biophysicists, geochemists, geomicrobiologists, and environmental microbiologists conducting multidisciplinary research with potential impact on biogeophysics in order to define the current state of the science, identify the critical questions facing the community, and generate a road map for establishing biogeophysics …
Date:
May 15, 2009
Creator:
Slater, L.; Atekwana, E.; Brantley, S.; Gorby, Y.; Hubbard, S. S.; Knight, R. et al.
Object Type:
Article
System:
The UNT Digital Library
The Ranger (San Antonio, Tex.), Vol. 79, No. 22, Ed. 1 Friday, April 15, 2005
Weekly student newspaper from San Antonio College in San Antonio, Texas that includes campus news along with advertising.
Date:
April 15, 2005
Creator:
San Antonio College
Object Type:
Newspaper
System:
The Portal to Texas History
Archer County News (Archer City, Tex.), No. 46, Ed. 1 Thursday, November 15, 1990
Weekly newspaper from Archer City, Texas that includes local, state, and national news along with advertising.
Date:
November 15, 1990
Creator:
Lobpries, F. Mike & Lobpries, Fran
Object Type:
Newspaper
System:
The Portal to Texas History
Surrogate-based optimization of hydraulic fracturing in pre-existing fracture networks
None
Date:
March 15, 2013
Creator:
Chen, M; Sun, Y; Fu, P; Carrigan, C R; Lu, Z & Tong, C H
Object Type:
Article
System:
The UNT Digital Library