Quote:
Originally Posted by AstralTraveller
So, they are going to share it?  If it is technically possible they could wind up with a baseline from NZ to SA. But where will the computing centre be?
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Hi David,
The original SKA architecture called for a 5km central core of antennas, a further mid-region
of a smaller number of dishes extending out 180km and then five spiral arms with dishes
spaced logarithmically out to 3000km.
Firstly keep in mind that in order to be useful, stations at the furthest distance
from the core need to have the target above the horizon.
Since the hour angle between West Australia and South Africa is approximately
six and three quarter hours, if the core was in one country and a long
baseline station in the other, targets would either have to be circumpolar
from both sites or have an appropriate range of limited zenith distances.
Keep in mind it is some 8500km between the two sites, much longer than
the original baseline proposal.
Secondly, the amount of data produced by the core is astronomical, exceeding the
current entire world internet traffic. This is sent by dedicated optical cables in trenches
to the on-site correlator. It is then distilled down where it is transferred to
the data center but still the amount of data is enormous.
In the Australian proposal, longer baseline stations will use fibres leased from the
NBN, possibly dark fibre. An optical fibre link to New Zealand would also be leased.
So in a nutshell, because of the enormous amount of data involved, the computing
center will need to be located in the same country as the core.
If one country was to act as a long baseline site for the other, dark fibre would
need to be leased connecting the countries. If it is available, it would be expensive,
as it is leased by the km.
Based on current trends, global internet traffic is presently increasing about 100 fold
every 12 years. One of the hopes therefore is that over the timescale of the SKA
construction, a leased dark fibre between the two countries may become less expensive
in relative terms.
However, whichever country the core is sited will also host the main computing
center and they will be fortunate indeed as they will be hosting the most powerful
purpose-built data handling system in existence.
Information is already one of the most important commodities of the 21st Century.
Those countries that fully embrace information and communications technologies
will have a large competitive edge over those that don't and exposure to a system
such as that proposed for the SKA could have enormous spin-offs.
But at the end of the day, it is all about the best science outcome and that is what
the new working group would have been charged with to investigate.