Opinion- 26 May 2012 |
Bryan Gaensler* Comments on the |
Professor Bryan Gaensler Director Centre for All-sky
Astrophysics, Sydney
University |
The Square Kilometre Array is
a concept that's been slowly growing and evolving since 1991. But today this
ambitious project took a sudden giant leap towards reality with the announcement
of the SKA site decision. The decision is a complex one, which recognises the
enormous amount of international investment that will be needed to make the SKA
happen: the array will be split between Africa and Australia/New Zealand.
What this does not mean is that half the telescope will be
built in each continent. Each site gets a full square kilometre of collecting
area, with the full scientific functionality originally envisaged. However, the
SKA's science goals require a facility that can tune into radio waves ranging
from 70 MHz up to above 10,000 MHz. It's impossible for any single technology to
cover this vast range, so the plan has always been to build two or even three
different types of antennas, which together can span the full range needed.
What the SKA project has decided is to put different
technologies in different places, playing to the strengths of each site.
The lowest frequency component, consisting of antennas that
do not move or steer and that can collect signals from the whole sky at once,
will be built in Australia and New Zealand. This capitalises on the superb radio
quietness of the SKA core planned for Murchison in outback Western Australia -
one of the few places on the planet that isn't polluted by FM radio and other
artificial signals in this low frequency band.
The higher frequency technology, consisting of more
traditional steerable dishes like the one at Parkes, will be built in Africa.
This naturally extends on the MeerKAT array of dishes already under construction
at the SKA core site in the Karoo desert region of South Africa.
The remaining piece of the puzzle are "phased array feeds",
the fish-eye lens technology being developed by CSIRO for their Australian SKA
Pathfinder (ASKAP) in Western Australia. These will be further developed and
expanded in Australia and NZ, and then possibly later installed on dishes in
Africa. Aus/NZ technology on an African telescope is truly a win-win scenario.
Going forward, what this all means is that the money
committed to construction by all the SKA's international partners can now begin
to flow. The hard-working engineers and scientists in Aus/NZ and in Africa can
go back to collaborating rather than competing. And the SKA will attract
brilliant young researchers from around the world to help solve the daunting
technological challenges ahead of us.
Few people will appreciate the small teams at the heart of
the two site bids who have sunk years of their lives into this project. For
Australia and NZ, special mention must go to the extraordinary CSIRO team lead
by Brian Boyle, Michelle Storey, Phil Diamond and Lisa Harvey-Smith, who made a
superb case for Aus/NZ to host the SKA. Africa, led by Justin Jonas and Bernie
Fanaroff, must also be congratulated, for creating a thriving African radio
astronomy community and a stellar SKA site bid from scratch in barely 10 years.
The governments involved have also all been extremely supportive: a positive
sign that amidst all the other pressures and challenges, basic research and
cosmic discovery still have a place in our nations' priorities.
I am excited that the SKA now looks like it's really going to happen. I can't wait to point it at my favourite stars and galaxies, and to get the data in my hands!
Credit Science: The Square Kilometre Array timeline and split.
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*Professor Gaensler's webesite is http://www.physics.usyd.edu.au/~bmg/