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 best way to label it would be 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. A VHF quad-helix array was fixed to a relocated Carnarvon AcqAid tower and antenna mount to fill the hole left by closure of the Carnarvon Tracking Station. 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 and made the voice link obsolete. By then the station had been expanded to include a Moblas 5, a mobile Satellite Laser Ranging (SLR) facility, in October 1979.

The SLR system:Image – Geoscience Australia
The SLR system:
Image – Geoscience Australia

Moblas is a NASA system using laser ranging to establish the relative position and velocity of a satellite and the tracking station to an accuracy of better than 1 cm with a single laser shot. A pulsed Laser light source is fired at the satellite, 'echoed' by a corner reflector and then received by a powerful optical telescope fitted 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 system; and

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

Return to WA in Space

Thanks to Trevor Mosel and Stan Parkes for thier help in defining the various dates in this account.

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