By Jonathan Amos

Science reporter, BBC News

Planck builds up a picture of the whole sky, one strip at a time

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The European telescope sent far from Earth to study the oldest light in the Universe has returned its first images. The Planck observatory, launched in May, is surveying radiation that first swept out across space just 380,000 years after the Big Bang. The light holds details about the age, contents and evolution of the cosmos. The new images show off Planck's capabilities now that it has been set up, although major science results are not expected for a couple of years. "The images show first of all that we are working and that we are able to map the sky," said Planck project scientist Dr Jan Tauber. "They show that in areas where we expect to see certain things, we do indeed see them, that we are able to image very faint emission, and finally that the two instruments are working in tandem well," he told BBC News. Background information Planck is a European Space Agency (Esa) endeavour. It was launched on an Ariane rocket and thrown out to an observing position some 1.5 million km from Earth. PLANCK SPACE TELESCOPE The Planck observatory always points away from the Sun and rotates once per minute As it rotates, it gathers precise temperature information from a narrow "strip" of the sky The strips are then fitted together to form an unprecedented thermal picture of our Universe It will take about six months to cover the whole sky. The aim is to map the sky at least twice

Planck achieves ultra-cold state It is trying to make the finest-ever measurements of what has become known as the Cosmic Microwave Background (CMB). This is light that was finally allowed to move out across space once a post-Big-Bang Universe had cooled sufficiently to permit the formation of hydrogen atoms. Before that time, scientists say, the Universe would have been so hot that matter and radiation would have been "coupled" - the cosmos would have been opaque. Researchers can detect temperature variations in this ancient heat energy that give them insights into the early structure of the Universe. With Planck, they also hope to find firm evidence of "inflation", the faster-than-light expansion that cosmologists believe the Universe experienced in its first, fleeting moments. Theory predicts this event ought to be "imprinted" in the CMB and the detail should be retrievable with sufficiently sensitive instruments. Planck is designed to have that capability. Its detectors, or bolometers, are the most sensitive ever flown in space, and operate at a staggering minus 273.05C - just a tenth of a degree above what scientists term "absolute zero". "In terms of the instrumental performance, we are getting what we expected from ground testing," explained Dr Tauber. Stripped-down The work to fully commission and optimise Planck for science was completed in mid-August. It was then immediately followed by the "first light" survey that produced the new images. The pictures are essentially maps of a strip of the sky, one for each of the nine frequencies Planck uses. Each map is a ring, about 15 degrees wide, stretching across the full sky. The telescope is kept phenomenally cold to carry out its work The telescope has now begun routine operations. It will take the observatory roughly six months to assemble a complete map of the sky. The mission objectives call for at least two of these maps to be made. It will be at least a couple of years before the Planck research teams are able to present some of their major scientific findings. "The mission has gone much better than I expected so far," said Dr Tauber. "It's been an unexpectedly smooth ride. We've had the usual minor hitches here and there, but I think overall it is doing fantastically well. Everything is chugging away and we are collecting data." Planck's co-passenger on May's Ariane launch was the Herschel Space Observatory. It views the cosmos at shorter wavelengths, in the far-infrared, allowing it to peer through clouds of dust and gas to see stars at the moment they are born. It is currently still in its demonstration phase, collecting images designed to show off its capabilities. Two of its instruments are working well. A third, however, is currently down after experiencing a fault. Engineers can switch to a back up system to reactivate the Heterodyne Instrument for the Far Infrared (HiFi) but they do not intend to do that until they can understand the cause the anomaly. HiFi is a spectrometer that will identify elements and molecules in the clouds of gas and dust which give rise to stars. Jonathan.Amos-INTERNET@bbc.co.uk



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