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  • 1
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    Space Nuclear Thermal Propulsion Test Facilities Subpanel (1993)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: On 20 Jul. 1989, in commemoration of the 20th anniversary of the Apollo 11 lunar landing, President George Bush proclaimed his vision for manned space exploration. He stated, 'First for the coming decade, for the 1990's, Space Station Freedom, the next critical step in our space endeavors. And next, for the new century, back to the Moon. Back to the future. And this time, back to stay. And then, a journey into tomorrow, a journey to another planet, a manned mission to Mars.' On 2 Nov. 1989, the President approved a national space policy reaffirming the long range goal of the civil space program: to 'expand human presence and activity beyond Earth orbit into the solar system.' And on 11 May 1990, he specified the goal of landing Astronauts on Mars by 2019, the 50th anniversary of man's first steps on the Moon. To safely and ever permanently venture beyond near Earth environment as charged by the President, mankind must bring to bear extensive new technologies. These include heavy lift launch capability from Earth to low-Earth orbit, automated space rendezvous and docking of large masses, zero gravity countermeasures, and closed loop life support systems. One technology enhancing, and perhaps enabling, the piloted Mars missions is nuclear propulsion, with great benefits over chemical propulsion. Asserting the potential benefits of nuclear propulsion, NASA has sponsored workshops in Nuclear Electric Propulsion and Nuclear Thermal Propulsion and has initiated a tri-agency planning process to ensure that appropriate resources are engaged to meet this exciting technical challenge. At the core of this planning process, NASA, DOE, and DOD established six Nuclear Propulsion Technical Panels in 1991 to provide groundwork for a possible tri-agency Nuclear Propulsion Program and to address the President's vision by advocating an aggressive program in nuclear propulsion. To this end the Nuclear Electric Propulsion Technology Panel has focused it energies; this final report summarizes its endeavor and conclusions.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-105708 , E-7781 , NAS 1.15:105708
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    NASA TECHNICAL REPORTS
  • 2
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    Nuclear Propulsion Project Workshop summary (1991)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: NASA-Lewis has undertaken the planning and coordination of a joint NASA/DOE/DOD Nuclear Propulsion Project which will investigate both nuclear electric and nuclear thermal concepts. The three-agency team has been tasked with the development of an Interagency Agreement and Memorandum of Understanding, as well as the drafting of a statement as to astronaut crew guidelines and values, the assessment of human-rating requirements, the development of an interagency safety and environmental assessment plan, and the development of test facility requirements. Attention is to be given to the role of SP-100 for nuclear-electric propulsion applications.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: In: Space nuclear power systems; Proceedings of the 8th Symposium, Albuquerque, NM, Jan. 6-10, 1991. Pt. 1 (A93-13751 03-20); p. 84-91.
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    NASA TECHNICAL REPORTS
  • 3
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    The effect of nitrogen on xenon ion engine erosion (1990)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: Erosion studies were performed on a 30-cm diameter J-series ion engine modified for operation on xenon propellant. The erosion rates of molybdenum and tantalum badges placed at different locations within the discharge chamber were measured as a function of the percentage of nitrogen (by mass) added to the xenon propellant. Reductions in the erosion rates of these badges of a factor of 8 to 50 were observed at nitrogen addition fractions between 0.5 to 2.0 percent. Reductions in cathode-side baffle erosion were achieved by adding nitrogen to the xenon propellant or by increasing the cathode orifice diameter. Analyses show that no significant degradation in ion engine performance should be expected at these nitrogen mass fractions. XRD, XPS and Auger analyses indicate the existence of nitrogen and nitrides in the surface of some but not all of the badges used in the tests where nitrogen was added to the xenon. Difficulty in identifying surface nitrides in the samples may be due to the existence of surface oxides and contaminants, or to the small thicknesses of the nitride layers.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 90-2591
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    NASA TECHNICAL REPORTS
  • 4
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    NLS cycle 1 and NLS 2 base heating technical notes. Appendix 3: Preliminary cycle 1 NLS base heating environments. Cycle 1 NLS base heating environments. NLS 2 650K STME base heating environments (1992)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: A preliminary analysis of National Launch System ascent plume induced base heating environments has been completed to support the Induced Environments Panel's objective to assist in maturing the NLS vehicle (1.5 stage and heavy launch lift vehicle) design. Environments during ascent have been determined from this analysis for a few selected locations on the engine nozzles and base heat shield for both vehicles. The environments reflect early summer 1991 configurations and performance data and conservative methodology. A more complete and thorough analysis is under way to update these environments for the cycle 1 review in January 1992.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-192454 , NAS 1.26:192454 , RTN-218-01 , RTN-218-03 , RTN-218-04 , RTN-250-6-01
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    NASA TECHNICAL REPORTS
  • 5
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    Athena: Advanced air launched space booster (1994)
    In:  CASI
    Details
    Publication Date: 2019-06-28
    Description: The infrastructure for routine, reliable, and inexpensive access of space is a goal that has been actively pursued over the past 50 years, but has yet not been realized. Current launch systems utilize ground launching facilities which require the booster vehicle to plow up through the dense lower atmosphere before reaching space. An air launched system on the other hand has the advantage of being launched from a carrier aircraft above this dense portion of the atmosphere and hence can be smaller and lighter compared to its ground based counterpart. The goal of last year's Aerospace Engineering Course 483 (AE 483) was to design a 227,272 kg (500,000 lb.) air launched space booster which would beat the customer's launch cost on existing launch vehicles by at least 50 percent. While the cost analysis conducted by the class showed that this goal could be met, the cost and size of the carrier aircraft make it appear dubious that any private company would be willing to invest in such a project. To avoid this potential pitfall, this year's AE 483 class was to design as large an air launched space booster as possible which can be launched from an existing or modification to an existing aircraft. An initial estimate of the weight of the booster is 136,363 kg (300,000 lb.) to 159,091 kg (350,000 lb.).
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-CR-197148 , NAS 1.26:197148
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    NASA TECHNICAL REPORTS
  • 6
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    Dependence of hydrogen arcjet operation on electrode geometry (1992)
    In:  Other Sources
    Details
    Publication Date: 2019-06-28
    Description: The dependence of 2kW hydrogen arcjet performance on cathode to anode electrode spacing was evaluated at specific impulses of 900 and 1000 s. Less than 2 absolute percent change in efficiency was measured for the spacings tested which did not repeat the 14 absolute percent variation reported in earlier work with similar electrode designs. A different nozzle configuration was used to quantify the variation in hydrogen arcjet performance over an extended range of electrode spacing. Electrode gap variation resulted in less than 3 absolute percent change in efficiency. These null results suggested that electrode spacing is decoupled from hydrogen arcjet ignition. The dependence of breakdown voltage on mass flow rate and electrode agreed with Paschen curves for hydrogen. Preliminary characterization of the dependence of hydrogen arcjet ignition on rates of pulse repetition and pulse voltage rise were also included for comparison with previous results obtained using simulated hydrazine.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 92-3530
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    NASA TECHNICAL REPORTS
  • 7
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    Performance evaluation of the Russian SPT-100 thruster at NASA LeRC (1994)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Performance measurements of a Russian flight-model SPT-100 thruster were obtained as part of a comprehensive program to evaluate engineering issues pertinent to integration with Western spacecraft. Power processing was provided by a US Government developed laboratory power conditioner. When received the thruster had been subjected to only a few hours of acceptance testing by the manufacturer. Accumulated operating time during this study totalled 148 h and included operation of both cathodes. Cathode flow fraction was controlled both manually and using the flow splitter contained within the supplied xenon flow controller. Data were obtained at current levels ranging from 3 A to 5 A and thruster voltages ranging from 200 V to 300 V. Testing centered on the design power of 1.35 kW with a discharge current of 4.5 A. The effects of facility pressure on thruster operation were examined by varying the pressure via injection of xenon into the vacuum chamber. The facility pressure had a significant effect on thruster performance and stability at the conditions tested. Periods of current instabilities were noted throughout the testing period and became more frequent as testing progressed. Performance during periods of stability agreed with previous data obtained in Russian laboratories.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-106401 , E-8235 , NAS 1.15:106401 , IEPC-93-094 , IEPC Conference; Sep 13, 1993 - Sep 16, 1993; Seattle, WA; United States
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    NASA TECHNICAL REPORTS
  • 8
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    A soft-start circuit for arcjet ignition (1993)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: The reduced propellant flow rates associated with high performance arcjets have placed new emphasis on electrode erosion, especially at startup. A soft-start current profile was defined which limited current overshoot during the initial 30 to 50 ms of operation, and maintained significantly lower than the nominal arc current for the first eight seconds of operation. A 2-5 kW arcjet PPU was modified to provide this current profile, and a 500 cycle test using simulated fully decomposed hydrazine was conducted to determine the electrode erosion during startup. Electrode geometry and mass flow rates were selected based on requirements for a 600 sec specific impulse (mission average) arcjet system. The flow rate was varied throughout the test to simulate the blow down of a flight propellant system. Electrode damage was negligible at flow rates above 33 mg/s, and minor chamfering of the constrictor occurred at flow rates of 33 to 30 mg/s, corresponding to flow rates expected in the last 40 percent of the mission. The soft-start current profile significantly reduced electrode damage when compared to state-of-the-art starting techniques.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: AIAA PAPER 93-2396 , ; 23 p.|AIAA, SAE, ASME, and ASEE, Joint Propulsion Conference and Exhibit; Jun 28, 1993 - Jun 30, 1993; Monterey, CA; United States
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    NASA TECHNICAL REPORTS
  • 9
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    Prelaunch self-discharge and charge-acceptance characteristics of the Hubble Space Telescope nickel hydrogen batteries (1991)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: Tests performed at NASA/MSFC on the Hubble Space Telescope (HST) nickel-hydrogen batteries (flight spare module and flight spare battery) were used to determine self-discharge and charge-acceptance characteristics when the batteries were exposed to charged wet-stand conditions, pulse charging on the launch pad, and battery capacity at solar array deployment. An equation is presented which was used to predict the capacity that would be available in the HST NiH2 batteries after an extended stand time on the launch pad plus up to 2 days on orbit prior to solar array deployment (either ground power or orbiter power were used to supply HST loads until shortly before the solar arrays were deployed). It is shown that a fairly accurate estimate of the available capacity was made.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: IECEC ''91: Intersociety Energy Conversion Engineering Conference; Aug 04, 1991 - Aug 09, 1991; Boston, MA; United States
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    NASA TECHNICAL REPORTS
  • 10
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    NASA/DOE/DOD nuclear propulsion technology planning: Summary of FY 1991 interagency panel results (1992)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Interagency (NASA/DOE/DOD) technical panels worked in 1991 to evaluate critical nuclear propulsion issues, compare nuclear propulsion concepts for a manned Mars mission on a consistent basis, and to continue planning a technology development project for the Space Exploration Initiative (SEI). Panels were formed to address mission analysis, nuclear facilities, safety policy, nuclear fuels and materials, nuclear electric propulsion technology, and nuclear thermal propulsion technology. A summary of the results and recommendations of the panels is presented.
    Keywords: SPACECRAFT PROPULSION AND POWER
    Type: NASA-TM-105703 , E-7092 , NAS 1.15:105703 , Nuclear Technologies for Space Exploration; Aug 16, 1992 - Aug 19, 1992; Jackson Hole, WY; United States
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