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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 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1977

Summary of the CTS Transient Event Counter data after one year of operation

The environmental charging of satellite surfaces during geomagnetic substorms is the apparent cause of a significant number of anomalous events occurring on geosynchronous satellites since the early 1970's. Electromagnetic pulses produced in connection with the differential charging of insulators can couple into the spacecraft harness and cause electronic switching anomalies. An investigation conducted to determine the response of the spacecraft surfaces to substorm particle fluxes makes use of a harness transient detector. The harness transient detector, called the Transient Event Counter (TEC) was built and integrated into the Canadian-American Communications Technology Satellite (CTS). A description of the TEC and its operational characteristics is given and the obtained data are discussed. The data show that the satellite surfaces appear to be charged to the point that discharges occur and that the discharge-induced transients couple into the wire harnesses.

Stevens, N. J.↗
NASA NTRS1978

CTS attenuation and cross polarization measurements at 11.7 GHz

The results of data obtained at The University of Texas at Austin during a total of 551 days of righthand circularly polarized transmission at 11.7 GHz from the CTS satellite are presented. Measured were attenuation, cross-polarization and rain rate. Results indicate that ice depolarization can be of significant importance.

Vogel, W. J.↗
NASA NTRS1978

CTS-type variable conductance heat pipes for SEP FM/PPU

The development effort for, and the fabrication and testing of, six CTS-type variable conductance heat pipes is described. The heat pipes are constructed of stainless steel, use methanol as a working fluid, and a nitrogen/helium mixture as the control gas. The wicking structure consists of interior wall grooves, a metal-felt diametral slab wick, and two wire-mesh arteries. The heat pipes are used to cool two Functional Model/Power Processing Units in a Solar Electric Propulsion prototype BIMOD thruster subsystem assembly. The Power Processing Units convert the electric power from a spacecraft solar array system to the voltages required to operate the electric thrusters which are part of the BIMOD assembly.

Antoniuk, D.↗
NASA NTRS1979

CTS 11.7 GHz isolation data for the calendar year 1978

Monthly and annual percent-of-time data on polarization isolation measured for the CTS spacecraft 11.7 GHz downlink are presented. The relationship between isolation and attenuation and the degree to which isolation can be predicted from attenuation data are discussed.

Bostian, C. W.↗
NASA NTRS1979

CTS attenuation and cross polarization measurements at 11.7 GHz

Attenuation and cross-polarization isolation at 11.7 GHz, measured at Austin, Texas by receiving the circularly polarized emissions from the CTS satellite are presented. A 12 month summary for Feb 78 to Jan 79 is presented. For .016 percent of the time the attenuation was greater than 10 dB, the isolation was less than 21 dB and the rainrate exceeded 55 mm/hr. Ice depolarization was observed frequently.

Vogel, W. J.↗
NASA NTRS1981

The CTS 11.7 GHz angle of arrival experiment

The objective of the experiment was to determine the statistical behavior of attenuation and angle of arrival on an Earth-space propagation path using the CTS 11.7 GHz beacon. Measurements performed from 1976 to 1978 form the data base for analysis. The statistics of the signal attenuation and phase variations due to atmospheric disturbances are presented. Rainfall rate distributions are also included to provide a link between the above effects on wave propagation and meteorological conditions.

Kwan, B. W.↗
NASA NTRS1981

Cloud Top Scanning radiometer (CTS): User's guide

The CTS maps the Earth's surface with a resolution of 0.1 km from an altitude of 18km with 60km side-to-side coverage of the field. It has three spectral channels. The 0.625 micrometer centered visual channel detects reflectance to within 1 percent. The 6.75 micrometer centered water vapor channel detects changes in temperature of less than one degree Kelvin at 175 K. The 11.5 micrometer centered infrared window channel detects changes of less one half degree Kelvin at 175 K. The data can be converted graphically into three display images of the scene. Values for scene temperature and albedo are calculated from calibration equations. The equations were derived from in-situ and laboratory measurements. Intercomparisons of the flight data temperatures with ground based and other remote sensor results established the certainty of the derived temperature values to within 3 K over a wide temperature range (180 to 320 K). The system performance, calibration, and operation is successful and the engineering information describing this system should prove useful to scientists and potential users of the data.

Brown, K. S.↗
NASA NTRS1975

Performance characteristics of the 12 GHz, 200 watt transmitter experiment package for CTS

The experiment package consists of a 200 W output stage tube (OST) powered by a power processing system (PPS). Descriptions of both the PPS and OST are given. The PPS provides the necessary voltages with a measured dc/dc conversion efficiency of 89 percent. The OST, a traveling wave tube with multiple collectors, has a saturated rf output power of 224 W and operates at an overall efficiency exceeding 40 percent over an 85 MHz bandwidth at 12 GHz. OST performance given includes frequency response, saturation characteristics, group delay, AM to PM conversion, inter-modulation distortion, and two channel gain suppression. Single and dual channel FM video performance is presented. It was determined that for 12 MHz peak to peak frequency deviation on each channel, dual channel FM television signals can be transmitted through the TEP at 60 W, each channel, with 40 MHz channel spacing (center to center).

Miller, E. F.↗
NASA NTRS1976

Dual frequency feed system for the CTS communications link characterization experiment

The developing, testing and installation of a dual frequency feed assembly were described. The feed has been designed to receive signals in the frequency range 11.7 to 12.2 GHz and transmit signals in the frequency range 14.12 GHz plus or minus 250 MHz. Complete performance data of the feed alone and installed in the 15 foot antenna is included herein. Drawings and descriptive information of the feed assembly are also given.

Gill, G. J.↗
NASA NTRS1975

Performance characteristics of the 12 GHz, 200 watt Transmitter Experiment Package for CTS

Measured performance characteristics from ground test of the Transmitter Experiment Package (TEP) for the Communications Technology Satellite are presented. The experiment package consists of a 200 W Output Stage Tube (OST) powered by a Power Processing System (PPS). Descriptions of both the PPS and OST are given. The PPS provides the necessary voltages with a measured dc/dc conversion efficiency of 89 per cent. The OST, a traveling wave tube with multiple collectors, has a saturated rf output power of 224 W and operates at an overall efficiency exceeding 40 per cent over an 85 MHz bandwidth at 12 GHz. OST performance given includes frequency response, saturation characteristics, group delay, AM to PM conversion, intermodulation distortion, and two channel gain suppression. Single and dual channel FM video performance is presented. It was determined that for 12 MHz peak to peak frequency deviation on each channel, dual channel FM television signals can be transmitted through the TEP at 60 W, each channel, with 40 MHz channel spacing (center to center).

Miller, E. F.↗
NASA NTRS1975

CTS reference book

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NASA NTRS1976

Preliminary report on the CTS transient event counter performance through the 1976 spring eclipse season

The transient event counter (TEC), senses and counts transients having a voltage rise of greater than five volts in three separate wire harnesses: the attitude control harness, the solar array instrumentation harness and the solar array power harness. The operational characteristics of TEC are defined and the preliminary results obtained through the first 90 days of operation including the spring 1976 eclipse season are presented. The results show that the Communications Technology Satellite was charged to the point where discharges occurred. The discharge induced transients did not cause any anomalous events in spacecraft operation. The data indicate that discharges can occur at any time during the day without preference to any local time quadrant. The number of discharges occurring in the one second sample interval are greater than anticipated. The compilation and review of the data is continuing.

Stevens, N. J.↗
NASA NTRS1976

CTS United States experiments. A progress report

The results are presented of the United States experiments activity to date. Wide segments of the population are involved in the Experiments Program including the scientific community, other government agencies, industry, and the education and health entities. The experiments are associated with both technological objectives and the demonstration of new community and social services via satellite.

Robbins, W. H.↗
NASA NTRS1976

OSU participation in the CTS communications link characterization experiment

A four element self phased array was developed for propagation measurements utilizing the Communication Technology Satellite 11.7 GHz downlink. The parameters of interest in measurements were attenuation, amplitude scintillation, and angle of arrival variability. Simultaneous scintillation measurements were also conducted at 360 MHz, 2.075 GHz, and 30 GHz utilizing ATS-6. The unique movement of ATS-6 during 1976 permitted extensive measurement of scintillation characteristics as a function of path elevation angle.

Hodge, D. B.↗
NASA NTRS1976

University resources sharing using the CTS

NASA-Ames Research Center and Stanford University in California, and Carleton University in Ottawa, Canada, are designing a curriculum-sharing experiment which will use compressed digital television. The experiment will permit evaluation of the potential of curriculum sharing by two universities which are geographically distant, but capable of transmitting and receiving television signals. The evaluation of the curriculum sharing per se will include inputs from faculty, staff and students at both institutions. Accessibility to and acceptability of each other's curriculum will be studied and recorded. Adjustments to differences in academic terms, class meeting times, teaching styles and similar issues will be closely monitored. It is hoped that this experiment will provide long-range planners the kind of information which they will need when designing large-scale educational telecommunications systems for the future.

Down, K. S.↗
NASA NTRS1977

A Depolarization and Attenuation Experiment Using the CTS and COMSTAR Satellites. Mathematical Formulations and Definitions for Dual Polarized Reception of a Wave Passing Through a Depolarizing Medium (A Polarization Primer)

The theoretical fundamentals and mathematical definitions for calculations involved with dual polarized radio links are given. Detailed derivations and results are discussed for several formulations applied to a general dual polarized radio link.

Stutzman, W. L.↗
NASA NTRS1977

CTS (Hermes): United States experiments and operations summary

The Communications Technology Satellite, launched in January 1976 and embodying the highest power transmitter in a communications satellite, was considered. As a joint program between the U.S. and Canada, close coordination of the two countries was necessitated since the management and control of experiments were done in real time. Criteria used by NASA for acceptance of the United States experiments are noted and acceptance procedures are discussed. The category for each accepted experiment is given. The modus operandi employed for the U.S. experiments in the areas of management, coordination, liaison, and real time operation are described. Some of the highlights associated with satellite utilization are given.

Donoughe, P. L.↗