Giant Camera Heads to Hawaii

Photonics.comFeb 2008
EDINBURGH, Scotland, Feb. 22, 2008 -- The UK Astronomy Technology Centre (UK ATC) at the Royal Observatory Edinburgh yesterday shipped its biggest and most complex instrument ever -- a four-ton camera the size of a car that is expected to make major discoveries about the origins of the universe.

The giant camera known as Scuba-2 is being transported to the James Clerk Maxwell Telescope (JCMT) atop a 14,000-ft mountain in Hawaii where astronomers expect it to reveal new information about the origins of galaxies, stars and planets. The camera will arrive at the telescope on the dormant volcano Mauna Kea in mid-March and begin initial science operations this summer. The Scuba-2, a four-ton camera that took seven years to build, is expected to make major discoveries about the origins of the universe once it is installed at the James Clerk Maxwell Telescope in Hawaii. (Images courtesy Science and Technology Facilities Council/UK ATC)
Rather than detecting visible light, Scuba-2 will detect submillimeter radiation, which is sensitive to the heat emitted by extremely cold dust in the universe. This material is associated with the mysterious earliest phases of the formation of galaxies, stars and planets. Typically the dust is at temperatures of about -200 °C and so detecting its extremely weak emissions presents a huge technological challenge.

"Submillimeter astronomy is a relatively new science and one where the UK has led the world over the past two decades. Our latest camera is the most powerful yet: Scuba-2 on the JCMT should detect the equivalent of the heat from a candle on the surface of the moon," said Wayne Holland, the project leader at the UK ATC.

In order to detect such low levels of heat, the detectors inside the camera must be as sensitive as possible. To achieve this they must be cooled to within a tenth of a degree above absolute zero (or about -273 °C), a huge technical challenge. To prevent the detectors being swamped by heat from the camera itself, the internal optics of the camera must also be cooled. As a result, the complete camera is the size of a car and weighs about 8000 lbs. Scuba-2 will be used with the James Clerk Maxwell Telescope on Mauna Kea, a dormant volcano in the Hawaiian Islands.
The superconducting detectors are the most sensitive thermal detectors ever built. Their design and construction was the result of a collaboration with the National Institute of Standards and Technology (NIST) in Boulder, Colo., and the Scottish Microelectronics Centre of the University of Edinburgh.

Professor Ian Robson, director of the UK ATC, said, "Scuba-2 is an incredible achievement; it is almost certainly one of the most complex projects that UK astronomers have ever attempted but it is also a project that is expected to produce amazing results. After seven years of construction in Edinburgh, the world's most powerful submillimeter camera by a huge margin is poised to open up a new frontier in astronomical research."

One of the most exciting astronomical discoveries of the past decade was made by Scuba, the predecessor to Scuba-2. Astronomers were surprised to detect a population of distant galaxies completely enshrouded in dust that had never been seen before. These galaxies are usually invisible to telescopes that detect visible light and can only be seen using submillimeter telescopes. They are known as primeval galaxies because they represent some of the earliest structures observable in the universe.

Over its eight-year lifetime, Scuba was able to produce images of only a hundred or so of these galaxies with each one taking several nights of valuable telescope time. In contrast, Scuba-2 is expected to be able to pinpoint and image many hundreds of these in a single night.

Pixel count in astronomical instruments is important, especially for surveying large areas of the sky, and Scuba-2 contains more than 10,000 pixels. "The closest rival camera has only a few hundred pixels. Scuba-2 will survey the sky 1000 times faster than any other instrument out there, with the exciting prospect of producing the first detailed map of the sky -- a true atlas of the cold universe," Robson said. Survey simulation: The large square is a simulation of a patch of sky covering an area of about four full moons -- the kind of area that Scuba-2 will explore with ease. The insets show the tiny areas that have been studied so far in the submillimeter, revealing superluminous primeval galaxies hidden from optical telescopes. Scuba-2 will be able to map the sky 1000 times faster than any other instrument and find thousands of these galaxies and explore their properties in great detail.
Professor John Peacock, head of the Institute for Astronomy at the University of Edinburgh, said he is excited about the prospect of using the new camera. "Earlier submillimeter cameras such as Scuba have taught us that galaxies like the Milky May formed most of their stars in an early dust-rich episode that we can't study with visible light. Scuba-2 will let us find thousands of galaxies in the earliest act of assembly, and study them in detail. It will be like moving from black-and-white film to 10-megapixel digital cameras. Astronomers can't wait for this wonderful machine to start producing results," he said.

Closer to home, Scuba-2 will survey giant molecular clouds where stars are currently being born and will search for the imprints of planetary systems on the cold dusty debris found around many nearby stars. This will entail observing around 500 stars and searching for the telltale signs that that planetary systems exist.

"One of the most exciting things Scuba-2 will do is to probe regions similar in size to our own solar system around nearby stars," Holland said. "This will tell us if there are other such systems out there and whether our solar system is unique."

The seven-year project to build Scuba-2 is the result of collaboration between the Science and Technology Facility Council's UK ATC, NIST, the University of Edinburgh, Cardiff University, the Joint Astronomy Center in Hawaii, and a consortium of Canadian universities, including the universities of Waterloo and British Columbia.

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