In preparation for what the BBC describes as the biggest European spaceflight launch in history, the two satellites Herschel and Planck are on the launch pad ready for lift off today at 1312 GMT.
Carrying the largest telescope to be flown in space, the Herschel Space Observatory will view the Universe at far infrared wavelengths. The Planck satellite will study the Cosmic Microwave Background (CMB) - the relic radiation from the Big Bang. Its mission is to understand the origin and evolution of our Universe and look for the seeds of modern day structures, such as galaxies and galaxy clusters, in the subtle variations in the CMB.
Photo credit: ESA
The satellites are at the launch site in French Guiana ready to be taken into space by the European Space Agency rocket Ariane 5, used for launching satellites into geostationary orbit, medium and low-Earth orbits and sun-synchronous orbits.
Photo credit: ESA S. Corvaja, 2009
Like NASA's recent shuttle launch, the ESA will be broadcasting the launch live online for free. To watch click here.
More info see the European Space Agency website