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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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NASA NTRS1982

LANDSAT-4 post launch report 1

LANDSAT-4 (formerly LANDSAT-D) was launched successfully at 1:59 p.m. EDT on July 16, 1982, from Vandenberg Air Force Base. The Delta 3920 launch vehicle performed flawlessly and placed the satellite into the planned three sigma low orbit of 694 km. The lower orbit was selected to eliminate a retrograde maneuver for the orbit adjust burns necessary to place the satellite into its planned operational 16-day repeat track at 705 km. Spacecraft separation and the initiation of solar array depolyment occurred, over the Indian Ocean tracking station. Spacecraft attitude rates at separation were low, allowing the Earth sensor to immediately acquire the Earth with the momentum wheels and without use of the propulsion system. All systems activated as of noon on July 18, 1982, are performing well with no significant discrepancies reported.

Source record↗
NASA NTRS1982

Evaluation of LANDSAT-D Orbit Determination Using a Filter/Smoother (PREFER)

Simulated range and range rate data for five tracking stations were first generated using batch least squares orbit determination (GTDS). Then GTDS was used (in the differential correction mode) to produce a nominal trajectory which was input to PREFER. The GTDS differential correction (DC) run was made using models which differed from those used to produce the simulated data. These model differences were chosen to be fairly realistic approximations to the errors in the models actually used for operational orbit determination. Several different simulation runs were made with different types of model errors in order to determine the sensitivity to these errors. The nominal trajectory and the simulated measurement data were input to PREFER to produce a smoothed ephemeris file. Numerous runs of PREFER were made in which parameters describing the statistics of the model errors were varied. The likelihood function computed by the Kalman filter determined the ""best'' choice of input parameters. There was strong negative correlation between the likelihood function and the errors in the smoothed ephemeris.

Gibbs, B. P.↗
NASA NTRS1982

A refined gravity model from Lageos /GEM-L2/

Lageos satellite laser ranging (SLR) data taken over a 2.5 yr period were employed to develop the Goddard Earth Model GEM-L2, a refined gravity field model. Additional data was gathered with 30 other satellites, resulting in spherical harmonics through degree and order 20, based on over 600,000 measurements. The Lageos data was accurate down to 10 cm, after which the GEM 9 data were used to make adjustments past order 7. The resolution of long wavelength activity, through degree and order 4, was made possible by the Lageos data. The GEM-L2 model features a 20 x 20 geopotential, tracking station coordinates (20), 5-day polar motion and A1-UT1 values, and a GM value of 398,600.607 cu km/sq sec. The accuracy of station positioning has been raised to within 6 cm total position globally and within 1.8 cm in baselines. It is concluded that SLR is useful for measuring tectonic plate motions and inter-plate deformations.

Lerch, F. J.↗
NASA NTRS1983

Radio metric orbit determination for the Giotto mission to Comet Halley

An international fleet of five spacecraft will fly past Comet Halley as it travels through the inner solar system in early 1986. This paper discusses orbit determination problems associated with the Giotto spacecraft, sponsored by the European Space Agency. The large number of spin axis precession maneuvers required to maintain the desired spacecraft attitude creates a new kind of radio metric orbit determination problem for this mission. This paper investigates the accuracy with which the Giotto spacecraft orbit can be determined relative to the earth or the sun, and establishes the sensitivity of this accuracy to the selection of the parameters to be estimated, the form of estimator used, the number of tracking stations employed, the length of the data arc, the selection of data types processed, and the levels of various error sources.

Wood, L. J.↗
NASA NTRS1983

The IRAS project organisation and mission operations

The project organisation of IRAS is described, showing the tasks assigned to each project group during post-launch operations. The satellite is described, emphasizing the detectors. In the task division, the role of the U.S. is to construct the telescope and survey instrument, launch the satellite, process final science data for the survey instrument, and provide certain standard satellite items. The Netherlands construct the spacecraft and three additional instruments, integrates and tests the overall satellite, and designs and participates in the development of the operational system. The U.K. provides the operational control center and primary tracking station, generates a system for preliminary science analysis of the survey data, provides housekeeping analysis software and science data distribution software, and staffs the control center operations. The teams involved in mission planning and operations, and their roles, are identified, and a block diagram of the operations organisation is presented.

Van Holtz, R. C.↗
NASA NTRS1984

Geosynchronous orbiter tracking by VLBI - Demonstration design

A demonstration has been designed to determine the three dimensional position of a satellite in geosynchronous earth orbit, with 5 meter accuracy, using tracking techniques based on very-long-base-line interferometry (VLBI). Two experiments are analyzed: the first uses tracking stations in California, Australia, and Guam, and the second uses stations in California, Australia, and Japan. Satellite VLBI observables are defined and measurement errors are predicted. Both experiments employ alternate observations between the satellite and extra-galactic radio sources to determine the satellite plane-of-sky position. Positional accuracy resulting from various combinations of data acquired over the satellite's orbital period is discussed. A strategy is devised for resolving integer cycle phase ambiguities, inherent in VLBI, without relying on an externally provided reference trajectory.

Border, J. S.↗
NASA NTRS1985

Measurement of the nighttime infrared luminosity of Spacelab 1 in the H- and K-bands

Infrared measurements of the Spacelab 1, Space Transportation System 9, were made from the Maui Optical Station tracking facility using a sensitive photometer n two infrared bands, the H-band centered at a wavelength of 1.6 microns and the K-band centered at 2.3 micrometers. The objective was to measure radiation from the vicinity of the Shuttle arising from interaction of Shuttle surfaces with atmospheric particles. It was necessary to include the Shuttle itself in the field of view of the photometer. The integrated brightness of the entire Shuttle at a distance of 400 km was found to be equivalent to that of a star of magnitude +6.6 or 1.6 microns; it was much fainter in the visible. Most of the emission at 1.6 microns appears to be attributable to the Shuttle glow phenomenon. It is hundreds of times brighter than the zodiacal background. The radiation at 2.3 microns can be accounted for primarily by diffusely scattered thermal radiation from Earth's surface.

Witteborn, F. C.↗
NASA NTRS1985

Relating the Planetary Ephemerides and the Radio Reference Frame

The positions of Venus, Mars, and Jupiter were obtained in the VLBI radio reference frame by measuring the position of a satellite (natural or artificial) of each planet relative to an extragalactic source in the radio catalogue. From the results for Mars and Venus it is concluded that the offset in right ascension of the radio frame from the dynamical equinox defined in DE200 is 0.00 sec +/- 0.04 sec. The observations for Jupiter imply a correction to its position from DE200 of -0.18 sec +/- 0.04 sec in right ascension and -0.06 +/- 0.05 sec in declination on 1983 April 29. The right ascension of Jupiter relative to the inner planets has been measured independently using Doppler tracking data near Jupiter encounter from Pioneers 10 and 11 and from Voyagers 1 and 2 by tying the tracking station positions, through previous spacecraft missions, to the DE200 ephemerides of the inner planets. This technique yielded a correction to Jupiter's right ascension of -0.22 +/- 0.05 sec, in good agreement with the results from the direct radio measurements.

Niell, A. E.↗
NASA NTRS1985

Geodetic and geophysical results from Lageos

Seven years of laser tracking of the Lageos spacecraft have been used to derive geodetic quantities describing the earth and its rotational motion. The dynamical motions of the solid-earth on its axis have been derived continuously since launch and changes in the length-of-day show very high correlation with variations in the atmospheric zonal winds between 1000 and 50 mbars. A significant improvement in the determination of the product of the earth's mass and the gravitational constant has been made. The high accuracy of the orbit determination of Lageos over the 7 years since launch has permitted the identification of a small deceleration in the nodal precession of the orbit. This deceleration is being caused by a small reduction in the flattening of the earth arising from the rebound of the earth after the last ice age. Measurements of the distances between the tracking stations over several years are showing changes consistent with tectonic plate motion and with general ideas of vertical movements.

Smith, D. E.↗
NASA NTRS1986

Intercontinental antenna arraying by symbol stream combining at ICE Giacobini-Zinner encounter

Deep space tracking stations on different continents were arrayed during the encounter of the International Cometary Explorer (ICE) spacecraft with the comet Giacobini-Zinner during September 9 through 12, 1985. This is the first time that telemetry signals received on different continents have been combined to enhance signal to noise ratio. The arraying was done in non-real time using the method of symbol stream combining. The improvement in signal to noise ratio was typically 2 dB over the stronger of the two stations in each array.

Hurd, W. J.↗
NASA NTRS1986

Precise interferometric tracking of the DSCS II geosynchronous orbiter

A demonstration of the precise tracking of a geosynchronous orbiter by radio metric techniques based on very-long-baseline interferometry (VLBI) has been jointly conducted by the Jet Propulsion Laboratory and Japan's Radio Research Laboratory. Simultaneous observations of a U.S. Air Force communications satellite from tracking stations in California, Australia, and Japan have determined the satellite's position with an accuracy of a few meters. Accuracy claims are based on formal statistics, which include the effects of errors in non-estimated parameters and which are supported by a chi-squared of less than one, and on the consistency of orbit solutions from disjoint data sets. A study made to assess the impact of shorter baselines and reduced data noise concludes that with a properly designed system, similar accuracy could be obtained for either a satellite viewed from stations located within the continental U.S. or for a satellite viewed from stations within Japanese territory.

Border, J. S.↗
NASA NTRS1985

White-light and radio sounding observations of coronal transients

A concerted search for coronal transients was conducted with the 'Solwind' coronagraph during the solar occultations of the two Helios spacecraft in October/November 1979. The polarization angle and bandwidth of the linearly polarized S-band downlink signal were monitored at the three 64-m tracking stations of the NASA Deep Space Network to determine coronal Faraday rotation and spectral broadening. A one-to-one correspondence could be established between abrupt disturbances in the two signal parameters and the passage of a white-light transient through the signal ray path from spacecraft to earth. The white-light morphology and the additional information provided by the radio sounding coverage are presented for each of the five distinct events recorded. Although no specific example could be observed in sufficient detail in both white light and Faraday rotation to derive the small-scale magnetic structure, some qualitative descriptions of the orientation and rough estimates of the magnitude of the transient magnetic field could be made.

Bird, M. K.↗
NASA NTRS1985

Navigation systems

The elements of the measurement and communications network comprising the global deep space navigation system (DSN) for NASA missions are described. Among the measurement systems discussed are: VLBI, two-way Doppler and range measurements, and optical measurements carried out on board the spacecraft. Processing of navigation measurement is carried out using two modules: an N-body numerical integration of the trajectory (and state transition partial derivatives) based on pre-guessed initial conditions; and partial derivatives of simulated observables corresponding to each actual observation. Calculations of velocity correction parameters is performed by precise modelling of all physical phenomena influencing the observational measurements, including: planetary motions; tracking station locations, gravity field structure, and transmission media effects. Some of the contributions to earth-relative orbit estimate errors for the Doppler/range system on board Voyager are discussed in detail. A line drawing of the DSN navigation system is provided.

Jordan, J. F.↗
NASA NTRS1987

Measurement technique of the Giotto radio science experiment

The paper describes the technique used to record time delay and waveform measurements for the Giotto radio science experiment of ESA's mission to comet Halley. The data were taken by using either two-way measurements (during pre- and post-encounter) or one-way measurements (during encounter with comet Halley), the downlink of the radio signal of the Giotto spacecraft being received at 8.4 GHz by the 64 m tracking stations of NASA's Deep Space Network (DSN). The waveform measurements were obtained at a sampling frequency of 50 kHz with an open-loop receiver assembly at DSN station Canberra as recently used for the Voyager/Uranus fly-by. Performance and calibration data are given as relevant to the radio subsystems on the ground and aboard Giotto.

Edenhofer, P.↗
NASA NTRS1988

Specification for IBM/IBM compatible 3480 tape cartridge

This document establishes the same kinds of standards and controls that are currently in use for the procurement on new analog and digital magnetic tapes. The Magnetic Tape Certification Facility (MTCF) currently maintains a Quality Products List (QPL) for all new analog and digital magnetic tapes purchased by NASA-GSFC. Extensive tests are conducted in the MTCF on an annual basis to determine the manufacturer's tape types to be added to or deleted from the current QPL. The MTCF currently maintains two specifications for magnetic tapes: NASA TM-79724 is used for the QPL and acceptance testing of new analog tapes; and NASA TM-80599 is used for the QPL and acceptance testing of new digital tapes. This specification will be used for the QPL and acceptance testing of new 3480 cartridges. The magnetic tapes used by GSFC, LaRC, ARC/Dryden, WFF, and the Network Tracking Stations are covered by the NASA-GSFC specifications. The 3480 cartridge was introduced approximately 3.5 years ago and is becoming an increasingly attractive alternative to digital magnetic tapes. Many users have already converted to the 3480 system and have more tape drives on order.

Perry, Jimmy L.↗
NASA NTRS1987

Development and implementation of a programmable telemetry processor

A programmable telemetry processor was designed for the NASA Goddard Space Flight Center in support of the Systems Utilization Enhancement (SUE) upgrade of the NASA tracking stations at Merritt Island, FL, and Bermuda. The processor is an integrated hardware and software system that performs the front-end telemetry synchronization and decommutation functions and provides for application-specific data processing. This paper presents the design, architecture, and features of the microprocessor controlled unit.

Flagg, Howard S.↗
NASA NTRS1987

S-Band ranging system for NASA mission support

The NASA Ground Network (GN) provides range and Doppler data for orbit determination of Space Shuttle and scientific missions from the Merritt Island, FL, Bermuda, and Wallops Island, VA, tracking stations. This paper describes a new generation of S-Band tone ranging equipment developed under the Goddard Space Flight Center, System Utilization Enhancement (SUE) Project. The Ranging Equipment incorporates several novel design features, emphasizing reliability and maintainability for support of NASA missions during the next decade.

Zilliig, David J.↗
NASA NTRS1987

Collaborative VLBI experiments with Radioastron

The USSR is planning to launch a 10-m radio telescope into earth orbit for use in VLBI observations. This mission (Radioastron) will be the first opportunity for astronomically important VLBI experiments with baselines much longer than can be obtained between telescopes on the earth. This paper describes the potential scientific advantages of combining data from the orbiting telescope with data from some of the very sensitive radio telescopes in western Europe, Australia, Japan, and the U.S. The advantages of using NASA's Space Network telescopes to track the Radioastron spacecraft when it is not visible from Soviet tracking stations are considered.

Jones, D. L.↗