Imperial physicists get ready for the launch of major new space telescopes<em> - News</em>

By Danielle Reeves
Thursday 14 May 2009

Physicists from Imperial College London are today celebrating the launch of two new multi-million euro space telescopes, which could transform our view of how planets, stars and galaxies are born, and give new insights into what the universe was like shortly after the Big Bang.

European Space Agency (ESA) space telescopes Herschel and Planck were launched together into space on an Ariane V rocket from French Guiana, today.

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Scientists from Imperial's Astrophysics research group have been involved with the two missions since they were first proposed 20 years ago. Now they are keen to see the software and instrumentation they have designed at work in space.

The larger of the two telescopes, Herschel, is the largest astronomical telescope ever to be put into space. It has a 3.5 metre wide super-strong ceramic mirror to capture long wavelength light from some of the coldest objects in the universe.

This 'far infrared' light makes up half the energy generated in the universe since the Big Bang, but it cannot be seen by the human eye or the Hubble space telescope. It can, however, penetrate the gas and dust clouds that hide some of the most interesting regions of the universe, where stars are formed, and where stars come together to form galaxies.

This means Herschel will provide scientists with a new way of looking at parts of the universe, and even our local galactic neighbourhood that they thought they knew quite well, explains Dr Dave Clements who leads Imperial's Herschel team:

"The great thing about Herschel is that it will reveal more about what's going on deep inside those massive dusty towers where stars and planets are formed, which we've seen with the Hubble telescope. There are tiny stars and cold molecular clouds in there that simply cannot be seen without a far infrared space telescope like Herschel, and it's important to see them, because they're part of the puzzle of how our galaxy and others like it were formed and have evolved."

Dr Clements and his colleagues at Imperial have been involved with the design of the SPIRE instrument on Herschel, which will take far infrared pictures of the sky, looking through freezing cold dust to reveal never- before-seen objects as cold as -268 degrees Celsius.

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The second telescope, Planck, shared a ride into space on the same rocket. Once up through the Earth's atmosphere, the two telescopes will break away from each other and the rocket, and begin their two-month journey to their chosen operational locations at the so-called "Lagrange Point 2", a spot in space where they can stay fixed in the same location relative to the Earth and the Sun.

Once operational, Planck will look at even longer wavelength radiation than Herschel. This radiation, known as the cosmic microwave background, is a relic or echo of the Big Bang itself. Once 1,000 times hotter than it is now, the cosmic microwave background has cooled over billions of years to 2.7 Kelvin or –270.45 degrees Celsius - close to absolute zero.

Fluctuations in the temperature of the cosmic microwave background can give scientists clues to what the universe's early years, after the Big Bang, were like. Planck will measure the temperature variations across this microwave background with much better sensitivity, angular resolution and frequency range than any previous satellite. The combination of these factors will give astronomers an unprecedented view of the universe when it was extremely young: just 380,000 years old.

Planck's 15 month mission will allow for two surveys of the entire sky. The data collected will help answer fundamental questions about the evolution of the universe, the amount and nature of dark matter, and the nature of dark energy – a hypothetical form of energy that may account for the universe's expansion at an accelerating rate.

Professor Andrew Jaffe from Imperial's Department of Physics, explains the significance of the mission, saying: "Planck's surveys of the whole sky will create the most detailed ever maps of microwave background radiation, and the ripples in it, that relate to cosmic activity in the aftermath of the Big Bang. From this data we will be able to learn more about how the fundamental characteristics of the universe, such as its shape, rate of expansion, and the density of matter, were determined."

On reaching their operating locations, both Herschel and Planck will undergo instrument tests and calibration before scientists on the ground can begin gathering data from the coldest regions of the Universe. The first results are expected in early 2010 for Herschel, with findings from Planck expected around three years after launch. Watch this space.....