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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 343 records · Page 19
All sourcesNASA NTRSDOE OSTI
NASA NTRS1998

AXAF-I Low Intensity-Low Temperature (LILT) Testing of the Development Verification Test (DVT) Solar Panel

The planned orbit of the AXAF-I spacecraft will subject the spacecraft to both short, less than 30 minutes for solar and less than 2 hours for lunar, and long earth eclipses and lunar eclipses with combined conjunctive duration of up to 3 to 4 hours. Lack of proper Electrical Power System (EPS) conditioning prior to eclipse may cause loss of mission. To avoid this problem, for short eclipses, it is necessary to off-point the solar array prior to or at the beginning of the eclipse to reduce the battery state of charge (SOC). This yields less overcharge during the high charge currents at sun entry. For long lunar eclipses, solar array pointing and load scheduling must be tailored for the profile of the eclipse. The battery SOC, loads, and solar array current-voltage (I-V) must be known or predictable to maintain the bus voltage within acceptable range. To address engineering concerns about the electrical performance of the AXAF-I solar array under Low Intensity and Low Temperature (LILT) conditions, Marshall Space Flight Center (MSFC) engineers undertook special testing of the AXAF-I Development Verification Test (DVT) solar panel in September-November 1997. In the test the DVT test panel was installed in a thermal vacuum chamber with a large view window with a mechanical "flapper door". The DVT test panel was "flash" tested with a Large Area Pulse Solar Simulator (LAPSS) at various fractional sun intensities and panel (solar cell) temperatures. The testing was unique with regards to the large size of the test article and type of testing performed. The test setup, results, and lessons learned from the testing will be presented.

Alexander, Doug↗
NASA NTRS1974

Asymptotic solution for solar electric low thrust orbit raising with eclipse penalty

This paper describes an analytic solution for the solar electric low thrust orbit raising problem derived by application of the two-variable asymptotic expansion method. Included in the formulation are the effects of (1) high initial eccentricity, (2) large change of inclination, (3) variable mass, and (4) earth shadow penalty including the rotation of the shadow axis relative to the osculating orbit. An advantage of this mathematical strategy is that the effects of various steering policies can be evaluated readily from a physical point of view.

Flandro, G. A.↗
NASA NTRS2012

EMI from Spacecraft Docking Systems Spacecraft Charging - Plasma Contact Potentials

The plasma contact potential of a visiting vehicle (VV), such as the Orion Service Module (SM), is determined while docking at the Orion Crew Exploration Vehicle (CEV). Due to spacecraft charging effects on-orbit, the potential difference between the CEV and the VV can be large at docking, and an electrostatic discharge (ESD) could occur at capture, which could degrade, disrupt, damage, or destroy sensitive electronic equipment on the CEV and/or VV. Analytical and numerical models of the CEV are simulated to predict the worst-case potential difference between the CEV and the VV when the CEV is unbiased (solar panels unlit: eclipsed in the dark and inactive) or biased (solar panels sunlit: in the light and active).

Norgard, John D.↗
NASA NTRS1992

Measurement of the solar limb brightness profile at 3 millimeters during the total eclipse of 1991 July 11

Observations of the solar limb at the point of first contact during the eclipse of 1991 July 11, with a spatial resolution of about 1.6 arcsec, are reported. The visibility amplitude and phase were modeled to yield the height of the 3-mm limb above the visible photosphere, and the data were differentiated to yield the brightness profile of the limb in strips about 1.6 arcsec wide. The 3-mm limb was found to extend 7.5 +/- 0.8 arcsec above the visible photosphere, with no evidence of a limb spike. The 3-mm limb, at a temperature of about 6500 K, extends to altitudes far beyond the expected location of the transition region in the model of Vernazza et al. (1981). A comparison of the 3-mm profile and an off-band H-alpha photograph of the limb reveals a close correspondence between the 3-mm limb and the height of H-alpha spicules.

Belkora, L.↗
NASA NTRS1988

A new Space Station power system

A new concept for a Space Station power system is proposed which reduces the drag effect of the solar panels and eliminates eclipsing by the Earth. The solar generator is physically separated from the Space Station, and power transmitted to the station by a microwave beam. The power station can thus be placed high enough that drag is not a significant factor. For a resonant orbit where the ratio of periods s:p is a ratio of odd integers, and the orbital planes nearly perpendicular, an orbit can be chosen such that the line of sight is never blocked if the lower orbit has an altitude greater than calculatable mininum. For the 1:3 resonance, this minimum altitude is 0.5 r(e). Finally, by placing the power station into a sun-synchronous orbit, it can be made to avoid shadowing by the Earth, thus providing continuous power.

Landis, Geoffrey A.↗
NASA NTRS1972

Delta-92 Telesat-A operations summary

Telesat-A, which is the first of the Canadian Telesat satellites to be launched for the domestic satellite communications system is described. The launch vehicle, designated Delta-92 consists of a DSV 3p-11 extended long tank first stage with an MB-3 engine, augmented by low-drag Castor 2 solid motors. The spacecraft has a spin-stabilized electronic system powered by 23,000 solar cells, with sufficient on-board battery capability to provide full capacity power during eclipse of the solar cells. A 60-inch wide circular directional antenna which remains constantly aimed at Canada is included.

Source record↗
NASA NTRS2013

Potential Applications for Radioisotope Power Systems in Support of Human Exploration Missions

Radioisotope power systems (RPS) for space applications have powered over 27 U.S. space systems, starting with Transit 4A and 4B in 1961, and more recently with the successful landing of the Mars Science Laboratory rover Curiosity in August 2012. RPS enable missions with destinations far from the Sun with faint solar flux, on planetary surfaces with dense or dusty atmospheres, and at places with long eclipse periods where solar array sizes and energy storage mass become impractical. RPS could also provide an enabling capability in support of human exploration activities. It is envisioned that with the higher power needs of most human mission concepts, a high efficiency thermal-to-electric technology would be required such as the Advanced Stirling Radioisotope generator (ASRG). The ASRG should be capable of a four-fold improvement in efficiency over traditional thermoelectric RPS. While it may be impractical to use RPS as a main power source, many other applications could be considered, such as crewed pressurized rovers, in-situ resource production of propellants, back-up habitat power, drilling, any mobile or remote activity from the main base habitat, etc. This paper will identify potential applications and provide concepts that could be a practical extension of the current ASRG design in providing for robust and flexible use of RPS on human exploration missions.

Cataldo, Robert L.↗
NASA NTRS1987

Development of an integrated heat pipe-thermal storage system for a solar receiver

The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low Earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the Earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at the potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube.

Keddy, E. S.↗
NASA NTRS1985

The 1984 eclipse of the symbiotic binary SY Muscae

Data from IUE spectra obtained with the 10 x 20-arcsec aperture on May 13, 1984, and optical spectrophotometry obtained with an SIT vidicon on the 1.5-m telescope at CTIO on April 29-May 1, 1984, are reported for the symbiotic binary SY Mus. The data are found to be consistent with a model of a red-giant secondary of 60 solar radii which completely eclipses the hot primary every 627 d but only partially eclipses the 75-solar-radius He(+) region surrounding the primary. The distance to SY Mus is estimated as 1.3 kpc. It is suggested that the large Balmer decrement in eclipse, with (H-alpha)/(H-beta) = 8.3 and (H-beta)/(H-gamma) = 1.5, is associated with an electron density of about 10 to the 10th/cu cm.

Kenyon, S. J.↗