The geospatial component of AuScope will establish and operate a comprehensive national geodetic infrastructure at increased levels of accuracy and time resolution. The new geospatial infrastructure will generate a significant quantity of data that will be used to improve the accuracy of Australia’s Reference Frame, as well as allow Australian scientists to investigate pressing questions such as sea-level variation. 

AuScope’s key geospatial infrastructure investment comprises new and upgraded:

• Very Long Baseline Interferometry (VLBI) systems;
• Satellite Laser Ranging (SLR) facilities;
• Global Navigation Satellite Systems (GNSS) ground stations and receivers; and
• Gravity measurement (GM) instruments.

VLBI and SLR are the key techniques to provide the long-term accurate determination of the fundamental components of a reference frame. VLBI is the most accurate technique available to define the scale and orientation of a reference frame, whereas SLR is the best technique to determine the origin of the reference frame and can also make a contribution to the scale. GNSS is the primary means in which the users can access the reference frame, and is the most effective way to provide a density of sites that allows accurate modelling of reference frame deformation. Gravity provides a link that is needed between the Cartesian coordinate system and the dynamic height system defined by level surfaces.

Very Long Baseline Interferometry (VLBI)

The AuScope investments include:

New VLBI sites at Yarragadee (WA) and Katherine (NT) and a replacement for the ageing Hobart (TAS) system consisting of 12m radio telescopes, atomic clocks, signal receivers and processing equipment. There may also be some building in frastructure at the Yarragadee and Katherine sites. This investment will link with the new VLBI antennae being acquired concurrently by our New Zealand collaborators.

A software interferometric signal correlator and associated dedicated hardware will be purchased, permitting near-real time ana lysis of the data collected under this program and will ultimately allow data from many VLBI sites to be streamed into the system via high speed internet and be correlated in near real time.

Satellite Laser Ranging (SLR)

An upgrade of components at the Mt Stromlo SLR site, including larger power modules and increased laser pulse fire rates, will enhance the ability of the system by increasing the distance it can range to high-orbit satellites thus permitting the GNSS system to be calibrated. This power upgrade will significantly improve ranging to the GNSS constellations (GPS, Glonass and the proposed Galileo System) allowing both optical ranging via SLR and radiometric ranging via GNSS to the same satellites; thus allowing for direct technique inter-comparisons and system calibrations.

NCRIS funding will also be used to bring a French mobile SLR system to Burnie (TAS) during 2007 as a pilot study for a possible future acquisition, enabling a continued presence in international altimeter programs. A mobile system will also allow for further co-location experiments with VLBI and GNSS sites.

Global Navigation Satellite Systems (GNSS Approximately 100 Sites)

The new GNSS network will be distributed across continental Australia. NCRIS funds combined with State funding will build approximately 100 new stations. Each site has one instrument package include GNSS receiver, antenna and meteorology equipment. This will compliment the existing Australian Regional Geodetic Network and State networks. Additional sites will add higher resolution to strain monitoring and have a direct beneficial impact on the refinement of the National Geospatial Reference System.

The minimum configuration required to meet the sea-level monitoring goals is 14 new permanent GNSS sites located near existing tide gauges.  The minimum configuration for creating a basic network for strain monitoring is about 30 sites distributed along two transects.  The final choice of transect will be decided in consultation with the Earth Imaging part of AuScope but a possible outcome is one east-west line at about the latitude of Perth and a north-south line at a longitude of about Alice Springs.

GNSS receivers will be acquired with the ability:

• To track the existing GPS and GLONASS constellations and their new signals (i.e. L2C), with the possibility of also tracking the Galileo constellation should it become operational later on.
• Be capable of streaming data in real-time and meteorological stations will be installed on site to aid atmospheric studies.

Gravity measurement

New absolute and relative gravimeters will be acquired, permitting regular gravity measurements to be made at strategic sites across the country.  The investment consists of upgrades to the gravity building at Mt Stromlo, the purchase of a relative gravimeter for the ANU and the purchase of a portable FG5 absolute gravimeter. The ANU in collaboration with Geoscience Australia will establish a national gravity observation program using the acquired equipment.

For more information on current and potential projects or accessing AuScope's Geospatial framework and earth dynamics infrastructure component for a project of your own please contact the program Director.

Program Director- Gary Johnston
Gary.Johnston@ga.gov.au