The Square Kilometre Array ( SKA), is an international radio telescope project; fifty times more powerful than the world's largest existing telescope with a collecting 'dish' of over a square kilometre. This means it will be the world's biggest and most powerful telescope.


The SKA will be able to reach out into the universe and address unanswered questions about our Universe. Dr Brian Boyle, CSIRO's SKA Director for Australia and New Zealand, explained that



This means we'll get an understanding of how we came to be....and who else might be out there! The SKA will also explore the role of magnetism in the cosmos, the nature of gravity, and the search for life beyond Earth. There are 70 institutes from 20 countries and their industry partners which are contributing to the project. Construction is due to start in 2016 and will cost nearly US $2 billion!
Technical facts about SKA
It's a multi-purpose radio telescope, covering the frequency range from 70 MHz to >25 GHz.
It's expected to be fully operational in 2024

It will play a key role in exploring or answering the Key Five Science Projects:

1. Probing the Dark Ages: investigating the formation of the early Universe as it made the transition from largely neutral to its largely ionized state today.
2. Galaxy Evolution, Cosmology and Dark Energy: probing the structure of the Universe and its fundamental constituent, galaxies, by carrying out all-sky surveys of continuum emission and of HI to a redshift z ~ 2. HI surveys can probe both cosmology (including dark energy) and the properties of galaxy assembly and evolution.
3. The Origin and Evolution of Cosmic Magnetism: magnetic fields are an essential part of many astrophysical phenomena, but fundamental questions remain about their evolution, structure, and origin. The goal of this project is to trace magnetic field evolution and structure across cosmic time.
4. Strong Field Tests of Gravity Using Pulsars and Black Holes: identifying a set of pulsars on which to conduct high precision timing measurements. The gravitational physics that can be extracted from these data can be used to probe the nature of space and time.
5. The Cradle of Life: probing the full range of astrobiology, from the formation of prebiotic molecules in the interstellar medium to the emergence of technological civilisations on habitable planets.

Three receptor technologies are under consideration for the SKA:

1. Dishes + Wide-band single pixel feeds. This implementation of the mid-band SKA represents a low risk approach to cover the 500 MHz to 10 GHz frequency range. The eventual upper frequency limit will depend on the outcomes of cost-effectiveness studies now being undertaken by a number of regional SKA projects.

This design approach is capable of supporting both the Phase 1 science case and most of the Phase 2 key science projects. It is currently the most appropriate technology for implementing the key science topics that require high fidelity imaging observations. 

2. Dishes & Phased Array Feeds. Many of the main SKA science projects involve surveys of the sky made at frequencies below ~3 GHz. To implement these surveys within a reasonable time frame requires a high survey speed.

By the use of a Phased Array Feed, a single telescope is able to view a considerably greater area of sky than would be the case with a single feed system. This greatly reduces the time to undertake a survey and can provide a cost effective way of reaching the SKA design goals.

3. Aperture arrays. An aperture array is a large number of small, fixed antenna elements coupled to appropriate reciever systems which can be arranged in a regular or random pattern on the ground. A beam is formed and steered by combining all the received signals after appropriate time delays have been introduced to align the phases of the signals coming form a particular direction.

By simultaneously using different sets of delays, this can be repeated many times to create many independent beams, yielding very large total Field of Views. The number of useful beams produced, or total Field of View, is essentially limited by signal processing, data communications and computing capacity.

Aperture arrays can readily operate at low frequencies and can provide large effective areas. Arrays using substantial digital processing systems are inherently very flexible since the system can 'trade' Field of View and bandwidth and hence provide an instrument that can be matched to that required by the experiment. 

http://www.skatelescope.org/

Ref: http://www.astronomywa.net.au/General-news/ska-updates.html
http://www.news.com.au/technology/sci-tech/ska-telescope-a-new-view-of-the-outback/story-fn5fsgyc-1226027358795
http://www.jb.man.ac.uk/ (for details of dishes and images)