South African pre-cursor to Square kilometer array radio telescope is already best in the southern hemisphere

The South African MeerKAT radio telescope, currently being built some 90 km outside the small Northern Cape town of Carnarvon, is a precursor to the Square Kilometer Array (SKA) telescope

The MeerKAT First Light image of the sky, released on July 16, 2016 by Minister of Science and Technology, Naledi Pandor, shows unambiguously that MeerKAT is already the best radio telescope of its kind in the Southern Hemisphere. Array Release 1 (AR1) being celebrated today provides 16 of an eventual 64 dishes integrated into a working telescope array. It is the first significant scientific milestone achieved by MeerKAT, the radio telescope under construction in the Karoo that will eventually be integrated into the Square Kilometer Array.

The Square Kilometer Array (SKA) is a large multi radio telescope project aimed to be built in Australia and South Africa. If built, it would have a total collecting area of approximately one square kilometer. It would operate over a wide range of frequencies and its size would make it 50 times more sensitive than any other radio instrument.

MeerKAT is a South African project to build an array of sixty-four 13.5-meter diameter dishes as a world class science instrument, and also to help develop technology for the SKA.

The Australian SKA Pathfinder, or ASKAP, is an A$100 million project to build a telescope array of thirty-six twelve-metre dishes. It will employ advanced, innovative technologies such as phased array feeds to give a wide field of view (30 square degrees). All 36 antennas and their technical systems were officially opened in October 2012.

Even operating at a quarter of its eventual capacity, South Africa’s MeerKAT radio telescope showed off its phenomenal power Saturday, revealing 1,300 galaxies in a tiny corner of the universe where only 70 were known before.

First Meerkat array images shows previously unseen galaxies and blackholes

MeerKAT Schedule

Array Release 1 (6 receptors) Engineering Verification completed by 5 April 2016
16 receptors and correlator available
Array Release 1 Science Commissioning completed 31 May 2016
once 6 done, the additional antennas gets added on a rolling basis (i.e. array commissioning significantly simplified)
16 Antenna Array Science capable by 30 June 2016 (Commissioning done and science capability, but science on PI projects not scheduled to start by then)

Array Release 2 (32 receptors) Engineering Verification completed Dec 2016 (additional single receptors Engineering Verification completed)
Array Release 2 (32 receptors) Science commissioning completed 31 March 2017
Early Science (PI projects) starts
WB Imaging
Pulsar Timing
additional science modes to follow
Array Release 3 (64 antennas) Engineering Verification completed mid 2017
Array Release 3 (64 antennas) Science Commissioning completed in 2017
WB Imaging
Pulsar Timing
additional science modes to follow

MeerKAT’s make-up

The MeerKAT telescope will be an array of 64 interlinked receptors (a receptor is the complete antenna structure, with the main reflector, sub-reflector and all receivers, digitisers and other electronics installed).

The configuration (placement) of the receptors is determined by the science objectives of the telescope.
48 of the receptors are concentrated in the core area which is approximately 1 km in diameter.

The longest distance between any two receptors (the so-called maximum baseline) is 8 km.

Each MeerKAT receptor consists of three main components:

  1. The antenna positioner, which is a steerable dish on a pedestal;
  2. A set of radio receivers;
  3. A set of associated digitisers.

The antenna positioner is made up of the 13.5 meter effective diameter main reflector, and a 3.8 meter diameter sub-reflector. In this design, referred to as an ‘Offset Gregorian’ optical layout, there are no struts in the way to block or interrupt incoming electromagnetic signals. This ensures excellent optical performance, sensitivity and imaging quality, as well as good rejection of unwanted radio frequency interference from orbiting satellites and terrestrial radio transmitters. It also enables the installation of multiple receiver systems in the primary and secondary focal areas, and provides a number of other operational advantages.

The combined surface accuracy of the two reflectors is extremely high with a deviation from the ideal shape being no more than 0.6 mm RMS (root mean square). The main reflector surface is made up of 40 aluminium panels mounted on a steel support framework.

This framework is mounted on top of a yoke, which is in turn mounted on top of a pedestal. The combined height of the pedestal and yoke is just over 8 m. The height of the total structure is 19.5 m, and it weighs 42 tons.

Meerkat array is one of four square kilometer precursor arrays that are currently being built

5 July 2016 – The Hydrogen Epoch of Reionisation Array (HERA) was granted the status of SKA precursor telescope by SKA Organisation, joining the three other SKA precursor telescopes located on the SKA sites in Australia and South Africa.

The SKA will combine the signals received from thousands of small antennas spread over a distance of several thousand kilometers to simulate a single giant radio telescope capable of extremely high sensitivity and angular resolution, using a technique called aperture synthesis.

The SKA will provide continuous frequency coverage from 50 MHz to 14 GHz in the first two phases of its construction. A third phase will then extend the frequency range up to 30 GHz.

Phase 1: Providing ~10% of the total collecting area at low and mid frequencies by 2023 (SKA1).
Phase 2: Completion of the full array (SKA2) at low and mid frequencies by 2030

The SKA is projected to cost €2 billion, this includes €650 million for Phase 1 completing 2020. The funding will come from many international funding agencies. The SKA and the European Extremely Large Telescope (E-ELT) are the two flagship facilities for ground-based astronomy in the future. They were formally equal high priority projects in the ASTRONET roadmap for European astronomy, but the E-ELT is now mostly funded.

SKA Search for extraterrestrial life
This key science program, called “Cradle of Life”, will focus on three objectives: protoplanetary discs in habitable zones, search for prebiotic chemistry, and the search for extraterrestrial intelligence (SETI).

The SKA will be able to probe the habitable zone of Sun-like protostars, where Earth-like planets or moons are most likely to have environments favourable for the development of life. The signatures of forming Earth-like planets imprinted on circumstellar dust may be the most conspicuous evidence of their presence and evolution, and may even detect planets capable of supporting life.
Astrobiologists will also use the SKA to search for complex organic compounds (carbon-containing chemicals) in outer space, including amino acids, by identifying spectral lines at specific frequencies.
The SKA will be capable of detecting extremely weak radio emissions “leakage” from nearby extraterrestrial civilizations, if existing

SKA mapping of Galaxies, cosmology, dark matter and dark energy

The sensitivity of the SKA in the 21 cm hydrogen line will map a billion galaxies out to the edge of the observable Universe. The large-scale structure of the cosmos revealed will give constraints to determine the processes resulting in galaxy formation and evolution. Imaging hydrogen through the Universe will provide a three-dimensional picture of the first ripples of structure that formed individual galaxies and clusters. This may also allow the measurement of effects hypothetically caused by dark energy and causing the increasing rate of expansion of the universe.

The cosmological measurements enabled by SKA galaxy surveys include testing models of dark energy, gravity, the primordial universe, fundamental cosmology tests, and they are summarized in a series of papers available online

SKA Epoch of re-ionization
The SKA is intended to provide observational data from the so-called Dark Ages (between 300,000 years after the Big Bang when the radiation stops and the universe cools) and the time of First Light (a billion years later when young galaxies are seen to form for the first time). By observing the primordial distribution of gas, the SKA should be able to see how the Universe gradually lit up as its stars and galaxies formed and then evolved. This period between the Dark Ages and First Light is considered the first chapter in the cosmic story of creation and the distance to see this event is the reason for the Square Kilometre Array’s design. To see back to First Light requires a telescope 100 times more powerful than the biggest radio telescopes currently in the world, taking up 1 million square metres of collecting area, or one square kilometer

SOURCES- Meerkat, Wikipedia

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