A discussion on orbital analysis - Radio tracking at Winkfield

1967 ◽  
Vol 262 (1124) ◽  
pp. 46-49
Keyword(s):  
Space Flight ◽  
Joint Venture ◽  
Radio Telemetry ◽  
Research Station ◽  
Radio Tracking ◽  
Goddard Space Flight Center ◽  
Telemetry Measurements ◽  
Orbital Analysis ◽  
The U.S

Winkfield is one of the stations in the Space Tracking and Data Acquisition Network (Stadan) of the U.S. National Aeronautics and Space Administration (N.A.S.A.) and is operated by the Radio and Space Research Station as a joint venture with N.A.S.A. The stations in the network, using standardized equipment supplied by N.A.S.A., receive by radio telemetry measurements from the various experiments in the satellites, they command the functioning of satellites and they track them. Tracking, with which this paper is concerned, means the measurement of quantities which contribute to the determination of the positions of satellites as a function of time. About ten stations in the network use tracking equipment and methods identical with those used at Winkfield. The network operates 24 h a day, its functioning being coordinated by the Goddard Space Flight Center of N.A.S.A. by means of teleprinter circuits which also serve to convey the raw tracking information from the stations to the N.A.S.A. computer facilities.

An assessment of radio telemetry for monitoring shorebird chick survival and causes of mortality

2019 ◽  
Vol 46 (7) ◽  
pp. 622 ◽  
Author(s):  
Daniel Lees ◽  
Tom Schmidt ◽  
Craig D. H. Sherman ◽  
Grainne S. Maguire ◽  
Peter Dann ◽  
...  
Keyword(s):  
Radio Telemetry ◽  
Radio Tracking ◽  
Chick Survival ◽  
Promising Technique ◽  
Free Living ◽  
Data Loggers ◽  
Significant Difference ◽  
Radio Transmitters ◽  
Causes Of Mortality

Abstract ContextMonitoring survival of free-living precocial avian young is critical for population management, but difficult to achieve. Perhaps the most promising technique available to track survival is the deployment of devices such as radio-transmitters or data loggers, which allow for tracking of the individuals. AimsTo understand if the deployment of radio-transmitters or the process of radio-tracking negatively impact chick survival by analysing survival of tagged chicks. MethodsFifty masked lapwing (Vanellus miles), 42 red-capped plover (Charadrius ruficapillus) and 27 hooded plover (Thinornis cucullatus) chicks were radio-tracked. Mortality between tagged and untagged chicks within broods was compared to examine whether radio-telemetry influenced chick survival. Key resultsThere was no statistically significant difference in survival between chicks with and without radio-transmitters. Radio-transmitters enabled the determination of cause of death for 0–28% of radio-tagged chicks. ConclusionThe survival of shorebird chicks does not appear to be affected by attachment of transmitters. ImplicationsRadio-tracking remains a promising way of studying the movement and survival of shorebird chicks, and is helpful but not reliable for assigning the cause of mortality.

scholarly journals A Laser Polar Motion Experiment

1972 ◽  
Vol 48 ◽  
pp. 121-122
Author(s):  
David E. Smith ◽  
Peter J. Dunn ◽  
Ronald Kolenkiewicz
Keyword(s):  
Space Flight ◽  
New York State ◽  
Earth Tides ◽  
Systematic Change ◽  
Orbital Inclination ◽  
Laser Tracking ◽  
Goddard Space ◽  
Chord Distance ◽  
Goddard Space Flight Center

SummaryFor three months in 1970, NASA, Goddard Space Flight Center conducted an experiment to try and detect the motion of the Earth's pole of rotation by laser ranging to an Earth satellite. Two laser tracking stations were used, one at Goddard Space Flight Center and one near Seneca in New York State, 408 km away and on the same meridian as the Goddard station. The objective of the experiment was to precisely measure the orbital inclination of the Beacon Explore C spacecraft, on a daily basis and with a resolution of a few hours, to a few hundredths of an arc second by the simultaneous tracking of the spacecraft as it passed between the two stations. During the experiment over fifty thousand range measurements on over two hundred revolutions of the satellite were obtained and on fifty occasions the satellite was simultaneously tracked at both stations. The noise accuracy of the tracking varied between 20 and 60 cm during most of the experiment and the orbital inclination obtained from the measurements showed a systematic change of about 25 arc sec, due primarily (about 80%) to the gravitational perturbation of the orbit by the Sun and the Moon. Perturbations by solar radiation pressure and the solid-Earth tides appear to account for most of the remaining systematic changes in the inclination and from which it has been possible to derive a value of Love's number for the Earth as A preliminary determination of the motion of the pole in the meridian containing the stations by subtracting the known perturbations (including tides) from the observed perturbation suggests that an accuracy of 3 to 5 m has been obtained, over periods of about 6 hr, during the latter part of the experiment. The experiment has also demonstrated that the present laser tracking systems are able to measure the chord distance between the two tracking stations with a repeatability of 25 to 30 cm.The present analysis of the data is directed towards an improved extraction of the gravitational perturbations and an improved determination of the Love number k2.A full account of the experiment and its results so far will be published elsewhere.

A Study of the Geoid in Canada

1974 ◽  
Vol 28 (3) ◽  
pp. 259-272
Author(s):  
Gérard Lachapelle
Keyword(s):  
New Brunswick ◽  
Satellite Data ◽  
Space Flight ◽  
Goddard Space ◽  
Goddard Space Flight Center ◽  
Map Service

An astrogeodetic determination of the geoid in certain parts of Canada was made with data available at the end of 1970. The astrogeodetic leveling method was used. The western and eastern parts of Canada were adjusted independently owing to the lack of data in the Province of Ontario. Five satellite stations located across Canada were chosen as initial points of the astrogeodetic geoid. Comparisons with two other astrogeodetic geoids — U.S. Army Map Service 1967 and University of New Brunswick 1973 — and one geoid obtained from a combination of gravimetric and satellite data— Goddard Space Flight Center 1972 — were made. A relative agreement of about five metres was found in every case for most parts covered by the present astrogeodetic geoid except in Newfoundland and Yukon.

scholarly journals Technical Note: Quantification of interferences of wet chemical HONO LOPAP measurements under simulated polar conditions

2008 ◽  
Vol 8 (22) ◽  
pp. 6813-6822 ◽  
Author(s):  
J. Kleffmann ◽  
P. Wiesen
Keyword(s):  
Technical Note ◽  
Swiss Alps ◽  
Pollution Level ◽  
Research Station ◽  
Polar Regions ◽  
Alpine Research ◽  
Absorption Photometer ◽  
Present Pilot Study ◽  
Good Agreement

Abstract. In the present pilot study, an optimized LOPAP instrument (LOng Path Absorption Photometer) for the detection of nitrous acid (HONO) in the atmosphere (DL 0.2 pptV) was tested at the high alpine research station Jungfraujoch at 3580 m altitude in the Swiss Alps under conditions comparable to polar regions. HONO concentrations in the range <0.5–50 pptV with an average of 7.5 pptV were observed at the Jungfraujoch. The diurnal profiles obtained exhibited clear maxima at noon and minima with very low concentration during the night supporting the proposed photochemical production of HONO. In good agreement with recent measurements at the South Pole, it was demonstrated, that interferences of chemical HONO instruments can significantly influence the measurements and lead to considerable overestimations, especially for low pollution level. Accordingly, the active correction of interferences is of paramount importance for the determination of reliable HONO data.

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