February 9, 2009

Herschel, Planck Set To Launch This Month

The European Space Agency is in the final stages of preparing to launch its Herschel spacecraft after more than 20 years of development.

Herschel will soon become the largest telescope mirror in space, overshadowing the Hubble space telescope.

"The mirror is an enormous piece of hardware," Thomas Passvogel, ESA's program manager on the Herschel space observatory, told BBC News.

"It's a ceramic mirror; it's the biggest piece ever made from silicon carbide. It's very hard but much, much lighter than glass and the performance is excellent."

Built by Thales Alenia Space, Herschel will study the formation of stars and galaxies like never before. Its vision is enhanced by infrared that uses longer wavelength radiation to see beyond what the naked eye can see.

"Very simply, the science pillars of Herschel are to understand better how stars and galaxies form and how they evolve," Göran Pilbratt, ESA's project scientist on Herschel, told BBC News.

Herschel will be sent in to an orbiting height of a million-and-a-half kilometers above Earth.

But in order for Herschel to detect objects in distant frigid climates, the space observatory must be kept extremely cold. The spacecraft itself is covered by a large shield that will keep it out of the sun. Scientists are also using a cryostat filled with more than 2,000 liters of liquid helium that cools the instruments and detectors to almost absolute zero (-273 degrees Celsius).

Herschel's instruments have been thoroughly tested at ESA's Space Research and Technology Centre (ESTEC) in Noordwijk, the Netherlands.

"Imagine one million, million, millionth of the brightness of a 60W light bulb - that's what we can detect with one of our detectors," said Professor Matt Griffin, who leads the international consortium behind SPIRE (Spectral and Photometric Imaging Receiver), one of Herschel's three instruments.

"Turning that around - imagine observing one of our very faint sources; let's say a very distant galaxy. If we were to observe it with SPIRE for a billion years, we would collect enough energy to light that 60W light bulb for just one-twentieth of a second," he added.

Herschel is expected to provide an unprecedented glimpse into how the Solar System began during the Big Bang 4.5 billion years ago.

"Herschel is not about studying mature stars or galaxies; it is really about studying the processes by which they are created," said Griffin.

"We know very little about that and we need to understand it in order to put together a picture of how the Universe we live in today grew from the earliest stages after the Big Bang."

On Feb. 6, ESA reviewed data collected during test campaigns over the past year. Following the review, teams from Herschel and Planck missions were given the green light to start the launch campaign.

Herschel will be transported to Kourou by plane on Feb. 11, and Planck will be transported to Kourou by plane on 18 February 2009. Both crafts are scheduled to launch into space in a dual launch configuration by an Ariane ECA rocket on April 16.

"Both spacecraft share the same service module, so there is an economy in building them together. And because you build them together, you have basically the same timing on each mission. So, overall, I think it is a good strategy, but a risky strategy," said Jacques Louet, Esa's head of science projects.


Image 1: Herschel in space, close up on its mirror. Credits: ESA (Image by AOES Medialab)

Image 2: Artist's impression of the Planck spacecraft Credits: ESA (Image by AOES Medialab)


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