Yatharagga: Satellite Laser Ranging (SLR) Station

Moblas 5 site: Photo - NASA
Moblas 5 site: Photo - NASA

This space station has had two names and two lives. Its first name was Yarragadee space station on Yarragadee pastoral property, but when the property was divided into two parts – Yarragadee and Yatharagga – the space station ended up on the Yatharagga property. NASA however still calls the space station, by its old name. The most correct way to describe it is as the Yarragadee SLR Station on the Yatharagga property.

The Yarragadee space station was opened in 1975 as an out-station of the Orroral Valley Tracking station to provide a VHF voice link to support the Apollo-Soyuz mission in July 1975 to fill the hole left by closure of the Carnarvon Tracking Station. A VHF quad-helix array was fixed to a relocated Carnarvon AcqAid tower and antenna mount. The voice link continued to be used for NASA’s Shuttle missions beyond the closure of Orroral Valley Tracking Station until the Tracking and Data Relay Satellite System (TDRSS) was in full operation. By then the station had been expanded to include a Moblas 5, a mobile Satellite Laser Ranging (SLR) facility, in October 1979.

Image:SLR system.bmp
: Image – Geoscience Australia

Moblas-5 is a NASA station using laser ranging to establish the relative position and velocities of the satellite being ranged to an accuracy of better than 1 cm with a single laser shot. A pulsed Laser light source is fired at the satellite, refected by a corner reflector and received by a powerful optical telescope with low level light sensors.

The Yarragadee site is important because of the relative paucity of locations in the Southern Hemisphere. The primary purpose of its measurements are to help define a geopotential field model of the Earth, the centre of its mass, the northwards drift of the Australian continental plate and its stability. The site facilities also include DORIS, a European Space Agency (ESA) Doppler satellite tracking system, GLONASS a Russian Federation Global Positioning system, and a GPS facility.

For more information see:

http://envisat.esa.int/instruments/doris/ for the ESA DORIS and

http://www.ga.gov.au/geodesy/gps/gpsoverview.jsp for GPS and GLONASS details

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