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Space 'time machine' takes first glimpse into the past

Cosmic Microwave Background

First images from the Planck space observatory<em> - News</em>

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By Danielle Reeves
Thursday 17 September 2009

The Planck space observatory, the European Space Agency's mission to study the early Universe, has successfully completed its initial test survey of the sky, it was announced today. The test confirms that Planck's sophisticated cooling system and scientific instruments, which Imperial College London physicists played a key role in developing, are working well.

Following the successful survey, Planck has now embarked on its 15 month mission to map the structure of the Cosmic Microwave Background radiation (CMB) – the relic radiation from the Big Bang.

Researchers from the astrophysics group in Imperial's Department of Physics have been involved in the Planck mission since it was first planned over 10 years ago. In particular, the Imperial team has been closely involved with developing software and systems for the high frequency data collection instrument on the observatory.

Over the course of the next 15 months, as the mission progresses, Imperial physicists will be responsible for determining determining the precise pointing of Planck's detectors, and for ensuring the 'sharpness' of its vision. This ongoing task will enable the international Planck team overall to extract the best possible measurements and science from Planck.


The images capture the plane of our own Milky Way galaxy running across the middle, and away from the plane are tiny fluctuations in the CMB shining through.

Imperial astrophysicists are involved in many aspects of that science, from measuring the primordial fluctuations that grew into the large-scale CMB structure seen in the Universe today, to Planck's ability to see galaxies in the more nearby Universe over an unprecedented range of wavelengths.

The 'first light' test survey that started on August 13 2009 lasted two weeks, during which time Planck surveyed the sky continuously, producing maps of a strip of the sky, one for each of Planck's nine frequencies. The images capture the plane of our own Milky Way galaxy running across the middle, and away from the plane are tiny fluctuations in the CMB shining through. These fluctuations are the main target of the Planck mission.

The properties of the tiny fluctuations in the CMB provide information about the earliest moments of the Universe's existence and how it evolved to become the Universe we see today. Planck is looking with finer resolution and greater sensitivity than previous satellites, and will allow the details of the Universe's age and composition to be calculated more precisely than ever before.

In addition, observing at nine frequencies means Planck can separate the CMB from the light emitted by the Galaxy at the same frequencies. As a result, Planck will also make unprecedented observations of our own Galaxy, detecting and characterising both gas and dust. Having maps at all nine frequencies allows the individual sources of microwave frequency light to be distinguished better than ever before.

Professor Andrew Jaffe from Imperial's Department of Physics, who will use data from Planck to study the CMB, wrote on his blog today:

"The last few months since the launch have been a lot of fun, getting to play with Planck data ourselves. Here at Imperial, our data-processing remit is fairly narrow: we compute and check how well the satellite is pointing where it is supposed to, and calculate the shape of its beam on the sky – ie. how blurry its vision is. Nonetheless, just being able to work at all with this incredibly high-quality data is satisfying."

Dr David Clements, also from Imperial, whose involvement in the Planck mission focuses on studying nearby galaxies, added:

"These images are fantastic. Planck is already doing better than the previous generation of CMB experiments. We've a while to wait before we finish the all sky survey, but these first results show we'll get spectacular results and new insights into the birth of the universe once it's done."

The Planck satellite was launched along with the Herschel satellite on May 14 2009 from Kourou, French Guiana, on an Ariane V rocket. During its six week journey to its observation point 1 million miles from Earth, the scientific instruments were cooled to extremely low temperatures, making Planck the coldest object in space at just 0.1 degrees above absolute zero. It took around six weeks for Planck to cool down to these low temperatures, after which a further six weeks were spent calibrating the instruments.

Routine operations started as soon as the First Light Survey was completed, and surveying will now continue for at least 15 months without a break. In approximately six months time, the first all-sky map will be assembled.

Within its allotted operational life of 15 months, Planck will be able to gather data for two full independent all-sky maps. To fully exploit the high sensitivity of Planck, the data will require a great deal of delicate adjustment and careful analysis. It promises to contain a treasure trove of data that will keep both cosmologists and astrophysicists busy for decades to come.

Professor Keith Mason, Chief Executive of the Science and Technology Facilities Council, which provides the UK funding for Planck, said, "It's great news that Planck is operating so effectively. UK researchers have invested a great deal of time and skill in this mission and we are all eager to find out what secrets Planck will reveal."

Images courtesy of the European Space Agency

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