Square Kilometre Array

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The Square Kilometre Array (SKA) is a radio telescope in development which will have a total collecting area of approximately one square kilometre.  It will operate over a wide range of frequencies and its size will make it 50 times more sensitive than any other radio instrument. It will require very high performance central computing engines and long-haul links with a capacity greater than the current global Internet traffic. It will be able to survey the sky more than ten thousand times faster than ever before.

With receiving stations extending out to distance of at least 3,000 kilometres (1,900 mi) from a concentrated central core, it will continue radio astronomy’s tradition of providing the highest resolution images in all astronomy. The SKA will be built in the southern hemisphere, in South Africa, Australia and New Zealand, where the view of our own galaxy, the Milky Way, is best and radio interference least.

With a budget of €1.5 billion, construction of the SKA is scheduled to begin in 2016 for initial observations by 2019 and full operation by 2024.[4][5] The project has its headquarters in Manchester, UK.

The organisation

The Square Kilometre Array is a global science and engineering project to build the world’s largest radio telescope. The project is led by the SKA Organisation, a not-for-profit company with its headquarters in Manchester, UK. The organisation was established in December 2011 to formalise relationships between the international partners and centralise the leadership of the project.

The Office of the SKA Organisation is growing rapidly and during 2012 staff will relocate from central Manchester into purpose built offices at Jodrell Bank in Cheshire, UK.

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The SKA Organisation is a private UK company limited by guarantee. The company does not have a share capital, but has members who are guarantors (with limited liability) instead of shareholders. Directors of the Board are appointed by the members.

Members of the SKA Organisation:

• Australia: Department of Innovation, Industry, Science and Research

• Canada: National Research Council

• China: National Astronomical Observatories, Chinese Academy of Sciences

• Italy: National Institute for Astrophysics

• New Zealand: Ministry of Economic Development

• Republic of South Africa: National Research Foundation

• The Netherlands: Netherlands Organisation for Scientific Research

• United Kingdom: Science and Technology Facilities Council

Associate member:

India: National Centre for Radio Astrophysics

The technology

In order to provide a million square metres of collecting area, the Square Kilometre Array demands a revolutionary break from traditional radio telescope design.

To achieve both high sensitivity and high-resolution images of the radio sky, the antennas (radio wave receptors), of the SKA will be densely distributed in the central region of the array and then positioned in clusters along five spiral arms – the clusters will become more widely spaced further away from the centre.

Three antenna types: dishes, mid frequency aperture arrays and low frequency aperture arrays, will be used by the SKA to provide continuous frequency coverage from 70 MHz to 10 GHz.

Combining the signals from all the antennas will create a telescope with a collecting area equivalent to a dish with an area of about one square kilometre.

The SKA will drive technology development particularly in information and communication technology.

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Spin off innovations in this area will benefit other systems that process large volumes of data from geographically dispersed sources. The energy requirements of the SKA also present an opportunity to accelerate technology development in scalable renewable energy generation, distribution, storage and demand reduction.

Pivotal SKA technology is being demonstrated with a suite of precursor and pathfinder telescopes and with design studies by SKA groups around the world. Key SKA technologies will be determined from these and many solutions will be selected and integrated into the final instrument.

The science

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 even life beyond Earth. If history is any guide, the SKA will make many more discoveries than we can imagine today.

Five key science projects have been selected:

1. How do galaxies evolve and what is dark energy?

The acceleration in the expansion of the Universe has been attributed to a mysterious dark energy. The SKA will investigate this expansion after the Big Bang by mapping the cosmic distribution of hydrogen. The map will track young galaxies and help identify the nature of dark energy.

2. Strong-field tests of gravity using pulsars and black holes

The SKA will investigate the nature of gravity and challenge the theory of general relativity.Pulsars, the collapsed spinning cores of dead stars, will be monitored to search for gravitational waves – ripples in the fabric of space-time. The SKA will also use pulsars to test general relativity in extreme conditions, for example close to black holes.

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3. Cosmic magnetism

The origin and evolution of Cosmic Magnetism

Everybody knows that the Earth is magnetic. The Earth’s magnetic field acts as a shield which protects us against energetic solar and interstellar particles; the Earth’s magnetism is vital for navigation, both for humans and for many other species too.

4. Cradle of Life

Searching for life and planets

Life on other worlds? A fundamental issue in astronomy and biology and an important question for humankind. Recent discoveries have shown that gas-giant planets (similar to Jupiter) are common around other stars like the Sun, though there is no direct evidence yet for potentially habitable, small, rocky planets like Earth. However, they probably exist. Remote sensing of young stars shows they are surrounded by dusty disks that contain the materials needed to form Earth-like planets. By observing the process of planet building, the SKA will tell us how Earth-like planets are formed. In addition, the SKA offers the possibility of detecting radio transmissions that would provide evidence for intelligent life among the stars.

5. Probing the Dark Ages

The first black holes and stars

Our understanding of cosmology has expanded greatly in recent years. On the one hand, detailed observations of the cosmic microwave background have shown us a ‘baby picture’ of the universe as it was only 300 000 years after the Big Bang.

Square Kilometre Array: IAS Preparation Online: Courtesy: AUT University



Square Kilometre Array : IAS preparation Online:

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