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Astronomie - Radioteleskop (Square Kilometre Array) SKA) in Südafrika-Update-5

25.06.2018

Swedish receiver to catch cosmic waves in the world's largest radio telescope

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In the South African Karoo Desert, the MeerKAT telescope’s 64 dish antennas will eventually become part of the world's largest radio telescope SKA. On one of the antennas the Swedish-built Band 1 feed is now being tested.

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​Just arrived in South Africa, Chalmers’ most advanced radio receiver is Sweden's main contribution to the record-breaking telescope SKA (Square Kilometre Array). The advanced prototype, now being tested in the Karoo Desert, is not only shiny and new. It’s also an important step towards a radio telescope that will challenge our ideas of time and space.
Onsala Space Observatory has delivered its largest technology contribution to the SKA (Square Kilometre Array) project. A metre (3 ft) across, the 180 kg (400 lb) instrument is the first in place of over a hundred to be mounted on dish antennas in the Karoo Desert, today home to the 64-dish-strong new MeerKAT telescope.
The Band 1 receiver, as it is called, allows the dish to measure radio waves with a frequency between 0.35 and 1.05 Gigahertz (wavelength 30-85 cm).
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The receiver is being tested on one of the 64 antennas in MeerKAT, one of today's largest radio telescopes and is in the same location in the Karoo desert where the SKA's antennas will be located. The instrument is a prototype manufactured in Sweden by Chalmers University of Technology in collaboration with Swedish industry, and it is designed to be mass-produced.
 
Sweden is one of 11 countries in the international SKA project, which will build the world's largest radio telescope at radio-quiet sites in Africa and Australia. The project is approaching the end of its design phase and construction is expected to start in the early 2020s.
 
As part of the SKA, Swedish receivers will participate in measurements of radio waves from many different sources in space. Scientists expect to make most sensitive radio measurements ever. They plan to test Einstein's theories to their limits and to explore the history of the universe by measuring millions of galaxies at distances of millions of light years.
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"This is a proud moment for us, getting a first glimpse of what the world's biggest radio telescope will be like. We work with developing the world's best receiver technology and hope that our contribution to the telescope will make it possible for humanity to see things we have never seen before", says Miroslav Pantaleev, project manager for SKA at Onsala Space Observatory.
 
The receiver’s journey to Africa has been preceded by intensive collaboration between researchers and engineers at Onsala Space Observatory together with industrial partners, to ensure both performance and resilience. Before its trip, the instrument underwent tough environmental tests in Sweden, both in Onsala and at Saab Bofors Test Centre in Karlskoga.
 
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John Conway, professor of observational radio astronomy at Chalmers and director of Onsala Space Observatory, looks forward beyond MeerKAT to the future dish array, SKA-mid.
"When the dishes in SKA-mid are operational, the world's astronomers will be able to access the world's most sensitive radio telescope and many exciting projects will be possible. We hope, among other things, to find new pulsars to test Einstein's theories, to study in detail how galaxies like the Milky Way were built during the history of the universe – and, of course, to make unexpected discoveries”, he says.
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1a (top). The Band 1 receiver has been installed on one of MeerKAT’s antennas. Out in the Karoo Desert in South Africa, 64 dishes today constitute the MeerKAT telescope. Later, these will be incorporated into the world's largest radio telescope, the SKA. On one of these antennas, Swedish technology is now being tested which will make the telescope the world’s most sensitive yet. In this image, the Swedish-built Band 1 receiver can be seen mounted underneath the dish's round white secondary mirror.
(Credit: SARAO)
  
1b. The Band 1 receiver’s protective cover reflects the desert Sun. To the right is the MeerKAT antenna’s secondary mirror.
(Credit: SARAO)
 
2. The Band 1 receiver captures a wide range of radio waves. A radio telescope with a dish antenna needs one or more feeds to guide radio waves with a wide range of frequencies up to the receiver equipment.
The Band 1 feed has a curved profile with four ridges on the inside. This Quadridge design was be adapted to SKA project requirements using mathematics, physics and optimisation algorithms, explains Jonas Flygare, PhD student at Chalmers.
“We determined the feed’s curved lines using algorithms that stochastically search for those shapes that best receive the radio waves, given our specifications. To find the optimum design you need to simulate a great number of different shapes of the antenna. The feed’s performance on the telescope has been evaluated together with EMSS Antennas in South Africa, and with a system simulator developed by Marianna Ivashina and colleagues at the Department of Electrical Engineering at Chalmers" says Jonas Flygare.
(Credit: Chalmers / Johan Bodell)
 
3. The engineers in the Band 1 project at Onsala Space Observatory. From left: Lars Wennerbäck, Miroslav Pantaleev, Jan Karaskuru, Per Björklund, Christer Hermansson, Leif Helldner, Bo Wästberg, Jonas Flygare, Lars Pettersson, Ronny Wingdén, Magnus Dahlgren and Ulf Kylenfall.
(Credit: Chalmers / Johan Bodell)
  
4. Vibration tests in Karlskoga. The receiver is subjected to tough vibration tests at Bofors Test Centre in Karlskoga. Video (10 sec) available.
Credit: Chalmers / Leif Helldner
 
5. Low noise amplifiers in the Band 1 feed for SKA. The Gothenburg company Low Noise Factory developed the unique low noise amplifiers (LNA) for SKA Band 1 that are visible in the middle of this image. They are specially designed for optimal performance without the need for cooling the feed.
(Credit: Chalmers / Johan Bodell)
 
More about the SKA project
 
The Square Kilometre Array (SKA) project is an international effort to build the world’s largest radio telescope, led by SKA Organisation. The SKA will conduct transformational science to improve our understanding of the Universe and the laws of fundamental physics, monitoring the sky in unprecedented detail and mapping it hundreds of times faster than any current facility.
 
The SKA is not a single telescope, but a collection of telescopes or instruments, called an array, to be spread over long distances. The SKA is to be constructed in two phases: Phase 1 (called SKA1) in South Africa and Australia; Phase 2 (called SKA2) expanding into other African countries, with the component in Australia also being expanded.
 
The SKA Organization is supported by 11 member countries - Australia, Canada, China, India, Italy, New Zealand, South Africa, Spain, Sweden, The Netherlands and the United Kingdom - and has brought together some of the world’s finest scientists, engineers and policy makers and more than 100 companies and research institutions across 20 countries in the design and development of the telescope. 
Sweden is represented in the SKA Organisation by Onsala Space Observatory, Chalmers University of Technology. Onsala Space Observatory is Sweden’s national facility for radio astronomy. The observatory is hosted by the Department of Space, Earth and Environment at Chalmers University of Technology, and is operated on behalf of the Swedish Research Council.
 
SKA's Dish Consortium is responsible for the design and testing of the dish that will be SKA-mid, one of two instruments in SKA. Chalmers and Onsala Space Observatory represent the Sweden Consortium, led by China and consisting of engineers and researchers at research institutes and companies in France, Italy, Canada, China, Great Britain, Sweden, South Africa and Germany.
 
More about SKA is available at http://www.skatelescope.org
 
 
More about the Band 1 receiver and Swedish industry in the SKA project
 
The receiver has been developed to capture the longest radio waves for which SKA's dish antennas are sensitive. The frequency range is called Band 1 and extends between 350 and 1050 MHz (wavelength 30-85 cm).
 
The project was led by Onsala Space Observatory, Chalmers. The design and system design of the feed was performed by Onsala Space Observatory and funded by the Swedish Research Council.
 
In industrial liaison for the project Chalmers has worked together with Big Science Sweden and Vinnova.
 
Several companies from both Sweden and abroad have also contributed to the project. Leax Arkivator, Gothenburg, Sweden, was responsible for the mechanical design of the feed. The metal parts were manufactured at Ventana Group in Hackås, Sweden, and at MegaMeta, in Kaunas, Lithuania. South Africa’s EMSS has delivered control electronics. System engineering work was coordinated by EMSS Antennas in South Africa and the South African Radio Astronomy Observatory (SARAO). The receiver’s amplifiers are developed by Low Noise Factory in Gothenburg, and were built in the clean room of Chalmers Nanofabrication Laboratory in Gothenburg. Industrial partners for the SKA project also include Omnisys, Gothenburg, Sweden, who developed design concepts early in the project. The overall project work was managed by CSIRO (Australia), CETC54 (China) and the SKA Organisation project office (UK).
Quelle: CHALMERS UNIVERSITY OF TECHNOLOGY - SE-412 96 GOTHENBURG, SWEDEN
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Update: 14.07.2018
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South Africa celebrates completion of gigantic, super-sensitive telescope

MeerKAT has drawn astronomers, engineers and data scientists from around the world.
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This image, based on observations made with South Africa’s MeerKAT radio telescope, shows the clearest view yet of the central regions of our galaxy.Credit: South African Radio Astronomy Observatory

Scientists and politicians in South Africa are together celebrating the official opening of a gigantic telescope that is already transforming astronomy research in the nation.

A ceremony that was live-streamed on national television stations on 13 July from a remote site in Northern Cape province marked the completion of the powerful MeerKAT radio telescope, which was designed in, and funded by, South Africa.

An array of 64 dishes, each 13.5 metres in diameter, MeerKAT is the most sensitive telescope of its kind in the world and will map the radio sky in unprecedented detail.

The 4.4-billion-rand (US$330-million) project will eventually form part of a future intercontinental facility called the Square Kilometre Array(SKA), which when complete will be the world’s largest radio telescope.

“With this new instrument, South Africa stands poised to be at the forefront of astronomy and data science,” SKA Organisation director-general Phil Diamond said at the launch. “The anticipated success of the SKA relies heavily on the MeerKAT.”

David Mabuza, the country’s deputy president, attended the ceremony, along with numerous members of his cabinet including the current science minister and four previous science ministers who all had a hand in driving the project.

“MeerKAT is an iconic instrument,” said Mabuza. “We take pride in the fact that a project of this magnitude was completed on time, within the projected budget.”

Milky Way imaged

Parts of MeerKAT have been collecting data since they were erected in 2016. At the ceremony, scientists unveiled an image made using all 64 dishes: the most detailed radio image of the centre of the Milky Way, which contains a supermassive black hole (see picture, above).

MeerKAT is expected to be completely science-ready in the next few months; two projects, one looking at fleeting astronomical events known as transients and another surveying hydrogen abundance in galaxies, are already underway. Transients include fast radio bursts, which can last for little as a few seconds and are one of the most perplexing phenomena in astronomy, while astronomers are interested in hydrogen because the abundant element is the fuel of stars, among other things, and can be used to trace the universe’s history.

MeerKAT uses a technique called interferometry in which many dishes or antennas together act as a single telescope. Each dish collects the relatively weak radio signals from space, which must be combined, filtered and turned into data that is useful to astronomers.

Astronomy ambitions

The project has spurred the country’s astronomy ambitions, which take advantage of conditions in places such as the Northern Cape, a sparsely populated area selected for its reliably cloudless skies. Those ambitions — and the allure of the SKA — have already attracted astronomers, engineers and data scientists from all over the world. Many of its SKA- and astronomy-specific research chairs – university positions dedicated to research and postgraduate training — have been conferred on foreign scientists, or attracted local scientists back from other countries.

"MeerKAT is what attracted me to South Africa," says Fernando Camilo, chief scientist at the South African Radio Astronomy Observatory, who moved from the United States in 2016 to South Africa to join the MeerKAT project.

In the early 2000s, before the country threw its hat into the ring to host the SKA and began a concerted effort to grow its astronomy-researcher base, there were about 10 dedicated radio astronomers, says Justin Jonas, chief technologist at the South Africa Radio Astronomy Observatory and an initial driver of the SKA project in South Africa. Many of its universities now have strong radio astronomy groups. “Back in the day, our astronomers went abroad to do astronomy, now we’re the attraction,” he says.

Scientists and officials expect that MeerKAT will continue to raise the profile of South African science. For now, scientists are itching to get their hands on the MeerKAT data "The provisional data is better than we expected," says Michael Kramer, director of the Max-Planck-Institut für Radioastronomie in Germany, who is involved in a project looking for transients and pulsars using MeerKAT.

He says that some of his colleagues have moved to South Africa to be part of the project, while others visit regularly. “Having the best telescope of its kind will do that.”

MeerKAT will accommodate eight ‘large survey’ projects, some headed by South Africans, some by foreign scientists, each allocated more than 1,000 hours of observing time over five years. More than half of these will investigate hydrogen, says Camilo. The remaining observing time, about one-third, will be allocated to astronomers worldwide through an open call.

The 64 MeerKAT dishes will eventually be absorbed into the first phase of the SKA, which will consist of another 130 dishes in South Africa and up to a 130,000 antennae in Australia. Construction is expected to begin in 2020.

Quelle: nature

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