Hi Folks;
I've just returned from a short break in Tassie where I was fortunate enough to have the time to drop in on some Radio Astronomers at the Mt Pleasant facility just outside of Hobart.
These guys are active participants in the Federal Government's National Collaborative Research Infrastructure Strategy (NCRIS). They tie Australian geodesy into the International Geospatial Reference Frame, which is tied to the International Celestial Reference Frame.
These guys are into Very Long Baseline Interferometry (VLBI) measurements, which provide the fundamental reference frame for all other types of geographic positioning techniques such as GPS. (VBLI was the first technique that directly measured the motions of the tectonic plates, and since 1998 is the only technique used to fix the Earth’s reference frame to celestial reference frames replacing the previous optical astronomy techniques). Mt Pleasant Observatory provides the fundamental position reference point for all of Tasmania.
They are doing precise measurements of the Australian continental drift which then spins off into other areas of astronomical research.
The overall project background is
here. So far, they have accurately measured the precise location of the Mt Pleasant 26m and 12m telescopes, with respect to other world-wide telescopes to centimetre precision (one part in a billion). They've measured the Australian continental plate, which is apparently, the fastest moving plate on Earth, (moving north-northeast at a rate of 5.779 cm per year and colliding with the Pacific and Eurasian Plates to the north).
There's a lot more they're up to as well.
This PDF gives a great outline of the full picture of what the overall project is about (albeit a bit out of date .. Sept 2008).
Notice the "Gravity Program" description:
Quote:
The FG5 gravimeter can measure gravitational acceleration (g) to one part in 109 (8th decimal place in m s-2), or the equivalent of ~3 millimetres of height change. Therefore, monitoring small gravity changes over long time periods will allow changes in surface height to be accurately measured independently of other survey techniques.
…
The relative gravity program consists of a series of relative gravimeters suited to tidal gravimetry that will be used to improve the understanding of temporal gravity variations caused by tidal forces. Currently researchers rely on predictive models that have yet to be tested over most of the Australian continent {note: as at Sept 2008}. Currently there is some doubt about the accuracy of the models, particularly in the northern part of the continent. The greatest improvement to the understanding of the tidal models will come from observing the dominant tidal frequencies (which are in the diurnal and semi-diurnal tidal bands, around one and two periods/cycles per day respectively).
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All measurements make use of measurements by the Satellite Laser Ranging Program which is used to accurately determine the variation of Earth’s centre of mass (over time), as the origin of the global reference frame.
If anyone could disprove a nonsense proposition like EE, these guys could do it in a heartbeat … and back it up with hard measurement data.
Cheers