Instrument Information
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| IDENTIFIER |
urn:nasa:pds:context:instrument:rss.vo2::1.2
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| NAME |
Viking Orbiter 2 Spacecraft Radio Science Subsystem
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| TYPE |
Radio Science
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| DESCRIPTION |
The Viking Orbiter 2 Spacecraft (VO2) Radio Science Subsystem (RSS) consisted of four distinct sets of Viking radio science data, three using orbiter data and one primarily using lander data with calibrations from orbiter data. The orbiter tracking data, obtained from the two-way, orbiter-earth S-band and X-band radio links, consisted of Doppler frequencies and time-of-flight range measurements. These determined the position and motion of the orbiters, and were used to study the Mars gravitational field, the plasma in interplanetary space, and the structure of the solar corona when the spacecraft was on the opposite side of the sun. The occultation data were obtained from these same radio links by analog recording of the signal when a spacecraft was passing into or out of occultation with Mars. The data were used to produce altitude profiles of the temperature, density, and pressure of the atmosphere (including the ionosphere) and to measure the radius of the planet using a large number of surface points. The surface properties aspect of this investigation utilized the UHF (381 MHz) signal on which the landers transmitted data to the orbiters. At the beginning or end of a data transmission session, when the orbiter was near the lander's horizon, the strength of the received signal was recorded as a function of time. These signal "fading patterns," resulting from interaction of the radio waves with the Martian surface, contained information about the physical properties of the surface near the landers. The lander tracking data from the two-way direct lander-earth S-band links permitted determination of the location of the landers and studies of the motion of the planet.
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| MODEL IDENTIFIER |
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| NAIF INSTRUMENT IDENTIFIER |
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| SERIAL NUMBER |
not applicable
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| REFERENCES |
Sjogren, W.L., Mars Gravity: High-resolution results from Viking Orbiter 2, Science, 203, 1006-1010, 1979.
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