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The array covers over 3000km.

But 81% of the antennas are within a 4km radius of the centre. At least for SKA Phase 1, which is the part they're seriously planning at this point; and for the mid-frequency array, which is the part being sited in South Africa. The reasons for this are fairly technical: the optimum distribution has a dense cluster of antennas near the centre, with a gradually sparser array as you go further out.

Source: this document (5.6 MB PDF), table 6, under the "Array Configuration" heading.

It's not a line. It's roughly a spiral. See https://www.skatelescope.org/l.... 3000 sqkm is probably the area of the radio-quiet park. But it's population, apart from the astronomers and engineers is tiny

Whoah. Are you even remotely aware of what is being done in cosmology these days?

Planck Sloan Digital Sky Survey
Square Kilometer Array
Ice Cube
Large Synoptic Survey Telescope
Euclid

Hardly "ideologically/branding driven pseudoscience". Who the hell modded you up?

can handle 10 times the traffic of today's Internet

Yeah, you can get something on the front page of slashdot if you use stupid, misleading metrics like this. Soulskill has his head buried in the sand.

A single computer, probably not.
Otherwise, the entire SKA will indeed produce 10 times the amount of data trafficking the today's internet.

And for good measure, now the actual paper:

http://www.skatelescope.org/uploaded/31235_139_Memo_Ford.pdf

Funny thing, I was reading this last night.

The location in WA is pretty damn close to the tropic. The SKA guys have a pretty concise list of site requirements (See http://www.skatelescope.org/the-sites/) - officially they care about noise floor, ionosphere/troposphere, climate, comms, costs, long term prospects of the noise floor. If I were selecting the site I'd care more about a location being politically stable.

GPS does not provide a good enough time reference for an application like this. Typically you need a hydrogen maser; these cost about $300K. The problem is that GPS has pretty poor short term stability - about +- 20 ns at 1 s for a low cost timing receiver. Averaged over one day GPS gives you a decent frequency reference but to average, you need another oscillator like a rubidium atomic clock. The rubidium gives you better short term stability and then you improve its long term stability by comparing it with GPS and adjusting it. But a rubidium isn't good enough either for the application. Providing suitable timing references to a distributed system is an active area of research. The paper "Phase transfer ..." http://www.skatelescope.org/publications/ gives you an idea of the timing requirements.

Looks like some people are jumping the gun a bit...

Typical, like when the Aussie's volunteered to host the World Cup Soccer because they 'knew' that South Africa was not up to it.

Better tell us when's the date the SkyNet is supposed to become self-aware.

August 29, 1997 July 25, 2003 July 25, 2004 sometime in 2005 April 21, 2011

Fear not, judgment day is like the rapture. It is always more profitable to rescheduled it the next year.

(See? See? Given the circumstances, wasn't it a non-trivial question?)

On a more serious line, I looked for when the SKA will become operational. It seems this is not too frequently asked one.

SKA - The SKA will give astronomers insight into the formation and evolution of the first stars and galaxies after the Big Bang, the role of cosmic magnetism, the nature of gravity, and possibly life beyond Earth.

SETI, the Search for Extraterrestrial Intelligence, is an exploratory science that seeks evidence of life in the universe by looking for some signature of its technology.

Exaflop computing is a requirement for the Square Kilometre Array. There is still a long way to go until there might be an upper limit, especially in Radio Astronomy.

http://www.skatelescope.org/
http://en.wikipedia.org/wiki/Square_Kilometre_Array
http://www.ska.gov.au/

"With the central core of the SKA located in this south-western part of the country the remote antenna stations would be located on easterly and northerly log spirals up to 3000 km away (Namibia, Botswana, Mozambique, Madagascar Mauritius, Kenya and Ghana)." skatelescope.org

That claim actually comes straight from the Square Kilometer Array website.

Sorry, by article I meant the journal article, not the press release type article, which I fully admit to not bothering to read.

Also, the hundreds of parsec possibility mentioned are not currently feasible because they depend on the Square Kilometer Array (SKA) which at the moment only exists on paper. It currently is in the early design phase and is not yet funded. Thus, if they try to get telescope time for this SETI project today, they will only be able to detect a signal out to 30pc according to one of the figures in the paper.

It's part of Astron's Square Kilometer Array (SKA) radio telescope project.

It's part of Astron's Square Kilometer Array (SKA) radio telescope project.

Not as impressive as Arecibo though. I was expecting more like an array but it really is just one giant dish.

It is *just* one big dish.. but it's also the world's largest full steerable telescope (aricebo isn't fully steerable). Also, it's one of very few off-axis paraboloid telescopes. (One of the nice things about this is the collection unit doesn't block any of the light that would be incident on the reflector.)

For impressive arrays, check out the VLA, ALMA (soon), or SKA (later). I was at the VLA last summer as part of my research (I do astronomy), it is very impressive. I was able to go into the dishes.. they're huge.

In practice, the Square Kilometer Array is intended to have a collecting area close to the physical area of one million square meters - requiring almost no gaps to exist between dishes.

My first calculation would be for dishes with a wider gap, which would give you much greater flexibility on pointing the damn thing, as you can't see through the other dishes. Personally, I consider this to be a much superior design, even though it would cost on the collecting area. Unfortunately, they are the ones being paid, even if I am the one who is right...

By way of comparison, Jodrell Bank Radio Telescope is a paltry 76 meters across, for a total collecting area of 4560 square meters, and that's one of the largest single steerable telescopes out there.

I'm going to guess that a collecting area about nine times that of Jodrell Bank, combined with a resolving ability that is, well, astronomical, you would get a very respectable image of Earth-like planets around other stars. If we accept the SKA group's claims, then you've a collecting area 250 times that of Jodrell Bank.

I first heard the 100LY=1 pixel resolution with SKA from Jill Tarter, head of the SETI Institute at a talk she gave at NASA Langley. From crunching the numbers, I can see nothing that could seriously contradict the claim. Even if you assume my model is the more reasonable implementation, the complete MERLIN network that has been detecting jovian planets for some time has only a fraction of that collecting area - probably something like a quarter or a fifth. (Aside from Jodrell Bank, the next-largest radio telescope in the UK is a paltry 32 meters across.)

If we go with SKA's claims, then we're talking about collecting possibly hundreds of times the total radiation, which would definitely be enough to spot even the tiniest of worlds - provided it had some characteristic reflected in the radio spectrum.

(It's also worth bearing in mind that networks such as MERLIN, which are hundreds of kilometers across, are set up for VLBI - very long baseline interferometry. That's fine, when you're talking about gas clouds or stars, but is probably none-too-hot for spotting very fast pulsars or rocky inner planets. On the other hand, a kilometer would let you use regular interferometry, which means these things would show up quite nicely.)

There are three drawbacks to all of this, and I'm surprised none of the posters has commented on them (so far). First, interferometry requires very exact timing of all the delays in the system, or it won't work. Let's go with the SKA estimate and say the dishes are 1 meter apart. Your clock must count an integral number of ticks for every meter the signal travels from the dishes, even after allowing for the natural variation in the data lines varying the speed of the signal. This is some astonishingly serious timekeeping.

The second problem is to keep the signal noise-free. Easy, for a giant single steerable dish - you plunk it in the middle of nowhere and surround it with a huge Faraday cage that only obscures the horizon. When you've a few tens of thousands - or millions - of very small dishes, the problem isn't so easy. The terrestrial radio sources will be far harder to screen out - not just

Go metric (Square Kilometer Array). Those from the US will think it's the biggest ever, will double its size in miles and fail horribly because somebody will have mixed up the miles with inches.

That's right. Canadians are also planning a Arecibo-scale steerable radio telescope, http://www.drao.nrc.ca/science/ska/, as a prototype element for the Square Kilometer Array, http://www.skatelescope.org/.

More indirect data on galaxy clustering and galaxy dynamics (especially of small galaxies) to help constrain the properties of dark matter (in particular the interaction of dark matter with other dark matter) would also be useful, as is noted in the paper.

This probably requires a number of astronomical surveys (mainly Sunyaev-Zeldovich effect surveys for galaxy clusters at microwave/mm-wave frequencies, and optical and radio surveys for galaxy dynamics) to give large datasets from which the statistical properties can be used to infer properties of dark matter over a range of length scales.

In Oxford we're also developing the instruments to carry out these surveys. In particular, various people will be developing the Square Kilometer Array http://www.skatelescope.org/ which will be the primary radio survey instrument from 2020, extremely large optical telescopes such as OWL, and technology for the next generation of S-Z effect surveys at mm wavelengths.

Dark matter particle direct search experiments, such as CRESST II are also under development, and should start operating on a similar timescale to the LHC.

When Lofar Meets Stella

350 KM Diameter Radio Telescope Array

I was talking to a professor in astronomy here and he mentioned about some of the conflicts between US and Europe regarding the plan. That is one of the reasons why US is also working on Square Kilometer Array. LOFAR imaging telescope are designed for the 10-240 MHz frequency range where as SKA will cover 0.15-20GHz or higher. Hopefully the two efforts will complement each other.

in Australia.

Site are here, here, and here.

Some technical details are here.

From the later,
The antenna has "...a proposed collecting area at low frequencies (150 MHz to 1.5 GHz) of roughly 1 km2 (or 106 m2) - the equivalent of more than one hundred dishes of 100 m diameter. In contrast, the largest and most sensitive existing array has a physical area approximately one hundred times smaller than this."

That's pretty big. :)