The Ariane 5 was delivered by industrial prime contractor EADS Astrium SpaceTransportation, which assembled the vehicle inside the Launcher Integration Building at Europe's Spaceport. This Ariane 5's handover occurred on March 9th when it was transferred to the Spaceport's Final Assembly Building, where Arianespace took over responsibility for payload integration and the final launch operations. The European Space Agency's Herschel space telescope and Planck observatory will be lofted by Ariane 5.
Planck was built by a Thales Alenia Space-led industrial team, and will measure the temperature variations across this microwave background with much better detail than any previous spacecraft —providing astronomers with an unprecedented view ofthe universe's first moments and the formation of galaxies. The observatory will have a liftoff mass of approximately 1,900 kg. for its launch by Ariane 5. The 3,300-kg. Herschel telescope will yield new data on how stars and galaxies are formed, as well as offer insights on how they continue to evolve. This spacecraft also was built under the responsibility of Thales Alenia Space, and it will have a mass at launch of about 3,300 kg. Both Herschel and Planck are to follow transfer trajectories for a 1.5 million-kilometer voyage to the second Lagrange point (L2) of the Sun-Earth system, where they will conduct their space science missions. The planned April 16 flight will be Arianespace's second Ariane 5 mission of 2009, with a total of seven launches targeted this year with the workhorse vehicle.