New Radio Telescope Improves Spatial Views
19 December 2008
New Zealand's first radio telescope promises new possibilities for national and global geodesy. As an important astronomical instrument, the radio telescope also boosts New Zealand's chance of co-hosting with Australia the megascience project the Square Kilometre Array (SKA).
The new $NZ1 million radio telescope was opened near Warkworth, north of Auckland, by the Auckland University of Technology (AUT) in October 2008. For geodesy, it is the atomic clock at the centre of the new telescope that offers an important opportunity.
In a technique called Very Long Baseline Interferometry (VLBI), AUT is able to measure the time difference between two or more earth-based radio telescopes when they receive data. The atomic clock, which provides the most accurate possible time-stamps when data is sent and received, means this difference can be translated into a physical distance with an accuracy of a few millimetres.
To harness this capability for geospatial precision, Land Information New Zealand (LINZ) installed a Global Positioning System (GPS) station at the site of the telescope in November 2008. An accurate tie will now be possible between the telescope antenna and the GPS antenna, which feeds data into PositioNZ, a LINZ network for tracking Global Navigation Satellite Systems like GPS.
Combining the data from the telescope and other PositioNZ stations will result in having more precise global reference frames, which are used to determine points on the Earth in relation to each other. This includes the International Terrestrial Reference Frame, which New Zealand uses to define the national coordinate system, the New Zealand Geodetic Datum 2000.
A more stable global reference frame also means measurements of changing sea levels and shifts in tectonic plates, as well as other Earth observations, will be more accurate.
Astronomical advantages
There are 15 radio telescopes operating around the world that make VLBI measurements, though few are operating in the southern hemisphere.
The SKA project could see the number of southern hemisphere telescopes expand greatly. Named for the total dish surface area involved, one square kilometre's worth, the project would see up to 5000 radio telescopes working as one, virtual super radio telescope.
For the astronomical sciences, radio telescopes and the SKA project can help us better understand the history of the universe and our place in it.
A major advantage of radio telescopes is that they can penetrate dust clouds in outer space that otherwise obscure views of important objects, such as the centre of our galaxy, the Milky Way.
The combined power of the SKA's telescopes would also enable scientists to observe radiation sources originating as far back as 13 billion years ago, close to the birth of the universe.
In Australia, 44 dishes will soon go live in a $Aus150 million trial. The core site of the Australian bid will be in Western Australia, with radio telescopes spread across the rest of Australia and several throughout New Zealand.
A working group supporting the SKA project has been formed in New Zealand, called Square Kilometre Array New Zealand, and is looking for support.
The successful bid will be chosen in 2011 by an independent panel, the International SKA Advisory Committee.
