Issue: September 2004
News
Measuring the impact of solar disturbances and detecting echoes from meteors...
Space eye reaches across the Tasman
The New Zealand component of the Tasman International Geospace Environment Radar (TIGER) will become operational in November. This follows the completion at La Trobe University of a radar to be installed near Invercargill, NZ, in October.
A ceremony was held at La Trobe's main Melbourne campus at Bundoora recently to mark the completion of the radar's construction.
Headed by La Trobe's Physics Department, TIGER is an important Australian contribution to space physics, facilitating research and providing services in space physics and space weather. La Trobe operates TIGER on behalf of a consortium of universities, government departments and commercial firms.
TIGER's first component to go into operation was a similar ionospheric radar with a 300 metre long antenna, installed on Bruny Island, Tasmania in 1999. It probes a fifty-two degree sector in azimuth with a range from 200 km south of Tasmania to the Antarctic coast 3,000 km away.
The New Zealand component is a similar but improved 'stereo' version of the Bruny Island radar. The radar electronics has just been completed at La Trobe and the antenna component is already installed on a farming property 15 km from Invercargill.
When the system becomes fully operational in November, TIGER's capability will be greatly enhanced. Each radar will emit beams that will cross, giving different line of sight velocities that can be combined to provide scientists with accurate 'vector' velocities of motions in the highly disturbed auroral ionosphere.
TIGER is part of an international network of similar radars called SuperDARN (Super Dual Auroral Radar Network) operated by ten nations to provide simultaneous coverage of both southern and northern polar regions.
The head of La Trobe's Physics Department, Professor Peter Dyson, and Dr John Devlin, an Associate Professor in the Department of Electronic Engineering, developed TIGER. Professor Dyson is TIGER's principal investigator and Dr Devlin its scientist-engineer and is responsible for the development of the radar system.
The NZ radar has been named 'Unwin' after New Zealander Dr Bob Unwin, who was a pioneer in ionospheric studies. He set up an auroral radar in Southland in 1957 and later explored the possibility of having a second radar in Tasmania.
TIGER will explore the impact of solar disturbances on Earth by monitoring the location of aurora and related phenomena occurring in the ionosphere - 100 to 300 km above the earth.
It explores an area half the size of Australia by directing HF radio signals via the ionosphere towards Antarctica and detecting weak echoes from structures in the ionosphere. These echoes are used to form images of the ionospheric structures and measure their speed and direction of motion.
It also detects echoes from meteors which are used to calculate wind speeds at heights of around 100km. It can also detect signals from the sea and methods of deducing the sea-state from these signals are being developed.
Results from the full operation of TIGER will include greater knowledge of space physics and space weather processes which is required to improve management of radio communications and navigation systems such as GPS. It also has relevance to satellite operations and magnetic surveying for minerals and electricity supplies.
When the sun's corona ejects huge amounts of matter that reach the Earth, there are rapid changes in wind speed and temperature in the ionosphere as well as the magnetosphere - that region where the earth's magnetic field interacts with the solar wind.
Auroras are caused by electrons striking molecules and atoms after entering the earth's atmosphere near the poles. The location of aurora can move 500 km in less than a minute during magnetic storms and can disrupt communication and navigation systems. TIGER monitors such storms and can provide real-time data on space weather storms.
TIGER uses HF radio waves in the 8 - 20 MHz range. It consumes only 2 kW of power, the same as some electric kettles, and transmits an average power of 200 W - the same as two bright light globes.
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