Yatharagga: Satellite Laser Ranging (SLR) Station

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The station was expanded to include '''Moblas 5''', a mobile '''Satellite Laser Ranging (SLR''') facility in mid 1978. The station was expanded to include '''Moblas 5''', a mobile '''Satellite Laser Ranging (SLR''') facility in mid 1978.
-[[Image:SLR system.jpg|left|thumbnail|210px|The SLR method:<BR>''Image – Geoscience Australia'']]+[[Image:SLR system.jpg|left|thumbnail|250px|The SLR method:<BR>''Image – Geoscience Australia'']]
[[Image:Laser.jpg|right|thumbnail|150px|The Mobile Laser:<BR>''Image – NASA'']] [[Image:Laser.jpg|right|thumbnail|150px|The Mobile Laser:<BR>''Image – NASA'']]
'''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 a reflecting satellite, 'echoed' by a corner reflector and then received by a powerful optical telescope fitted with low level light sensors. The prime satellite supported is '''Lageos''' (Laser Geodynamic Satellite) launched on 4 may 1976 and expected to stay in orbit for 8 million years. It is encrusted with 426 highly precise corner reflectors. '''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 a reflecting satellite, 'echoed' by a corner reflector and then received by a powerful optical telescope fitted with low level light sensors. The prime satellite supported is '''Lageos''' (Laser Geodynamic Satellite) launched on 4 may 1976 and expected to stay in orbit for 8 million years. It is encrusted with 426 highly precise corner reflectors.

Revision as of 07:17, 2 May 2007


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

This space station has had two names - Yarragadee and Yatharagga - and two functions: ‘astronaut voice communications’ and ‘Laser ranging’. In both manifestations it was part of NASA’s Satellite and Data Tracking Network (STDN) operating as a sub-station from Orroral Valley Tracking Station, Canberra, until that closed in 1985. It now operates as part of the International Laser Ranging Service (ILRS).

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 astronaut 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.

The station was expanded to include Moblas 5, a mobile Satellite Laser Ranging (SLR) facility in mid 1978.

The SLR method:Image – Geoscience Australia
Enlarge
The SLR method:
Image – Geoscience Australia
The Mobile Laser:Image – NASA
Enlarge
The Mobile Laser:
Image – NASA

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 a reflecting satellite, 'echoed' by a corner reflector and then received by a powerful optical telescope fitted with low level light sensors. The prime satellite supported is Lageos (Laser Geodynamic Satellite) launched on 4 may 1976 and expected to stay in orbit for 8 million years. It is encrusted with 426 highly precise corner reflectors.

The station also housed a Laser Protection Surveillance Radar to ensure that aircraft would not enter the beam of the laser transmitter. The ‘radar log’ shows it was operational in July1978 but laser tracking may not have started until December ‘78.

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 geo-potential 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 DORIS system; and

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


Return to WA in Space


Thanks to Trevor Mosel and Stan Parkes for their help in defining the various dates in this account, and to Soula Veyrader for access to the surveillance radar records held by Melville City Council, Perth.

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