March 6, 2009

ESA Prepares To Launch Two Cousin Telescopes Into Orbit

The Kourou spaceport in French Guiana is gearing up to send Europe's Herschel and Planck space telescopes into orbit next month, BBC News reported.

The satellite observatories are part of a 10-year joint program worth over $2 billion and will come face to face for the first time during their arrival in the S1 preparation hall at Kourou.

Thomas Passvogel, the Herschel-Planck project manger with the European Space Agency (ESA), said the two were once at a technical center in Holland at the same time, but there was a wall separating them.

"It's great to have them finally in the same room," he told BBC News.

A single Ariane rocket is set to carry the satellites"”Europe's most valuable payload in the name of science"”into orbit on April 16.

The largest satellite, Herschel, is a far-infrared and sub-millimeter telescope that will help researchers discover how stars and galaxies form and how they evolve.

The Cosmic Microwave Background "” a "fossil light" that pervades the entire Universe and is detectible at radio wavelengths "” will be the primary focus for Planck. Scientists hope it will provide new insights into the development of the cosmos and why it looks the way it does now.

The telescope's sensitive mirrors have been covered to protect them from contamination; before the launch, ground crews will check them over to make sure they weren't damaged in transit from Europe.

The observatories' instrument teams are finishing up any last minute inspections and leaving Kourou.

"It's been many years of work to build and test the instrument. And to see it here with its telescope, constructed and ready to go - it's wonderful," said Tanya Lim, from the STFC-Rutherford Appleton Laboratory, who built Herschel's SPIRE instrument.

Pending inspection approval, the satellites will be moved to the spaceport's fuelling hall, where their tanks will be pumped full of hydrazine in order to power the thrusters the spacecraft will use to make orbital corrections.

Cooling systems will also need to be primed, since both observatories' instruments are required to operate at extremely cold temperatures. More than 2,000 liters of super-fluid helium will be loaded into Herschel's cryogenic tank.

Planck will sit underneath its larger cousin at the top of the Ariane during their rapid ascent through the Earth's atmosphere.

The integration phase for the Ariane vehicle is nearing completion, as the solid rocket boosters have been attached to the central core stage. Next week, crews will move the whole structure to the final assembly shed to await the arrival of the passengers.

Jean-Jacques Auffret, from rocket operator Arianespace, said once Herschel and Planck are assembled onto payload adaptors, the fairing would be closed and hoisted on top of the launcher.

"After that there will be tests to ensure that all electrical links are OK. And then we roll out," Auffret said.

This will be the first time Ariane has sent spacecraft to the second Lagrangian point (L2)"”a gravitational "sweet-spot" that lays away from Earth in the direction opposite the Sun"”meaning the satellites will make fewer orbital corrections over their lifetimes.

ESA officials are hopeful in their decision to fuse the Herschel and Planck programs.


Image 1: The gigantic telescope of ESA's space-based infrared observatory, Herschel, is being prepared to be assembled with its spacecraft. Herschel's telescope, which will carry the largest mirror ever flown in space, has been delivered to ESA's European Space Research and Technology Centre, ESTEC, where engineers and scientists are busy with the final steps that will prepare the infrared observatory for launch in late 2008. Credits: ESA

Image 2: This artist's impression shows the focal plane of the two instruments on board ESA's Planck spacecraft. The instruments detect the collected radiation differently. The Low Frequency Instrument (LFI) is designed to convert the lower energy microwaves into electrical voltages, rather like a transistor radio. The High Frequency Instrument (HFI) works by converting the higher energy microwaves to heat, which is then measured by a tiny electrical thermometer. The instruments share a common telescope. Credits: ESA (Image by AOES Medialab)


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