The second Ariane 5 launch of 2009 is now scheduled for a May 6 liftoff, following additional flightworthiness checks performed on one of its two payloads: the Herschel space telescope.
These verifications — requested by the mission's customer, the European Space Agency — were made to ensure the Herschel telescope's mirror structure has sufficient design margins for the flight loads it will experience during Ariane 5's ascent. The telescope mirror will be the largest ever launched into space, and was built by brazing 12 silicon carbide petals into a single piece. Both Herschel and its Planck co-passenger on the upcoming Ariane 5 mission will study the universe's origins. With a liftoff mass of 3,300 kg., Herschel is designed to investigate how stars and galaxies are formed, as well as provide information on how they continue to evolve. Planck was conceived to observe the Cosmic Microwave Background radiation and will have a mass at liftoff of approximately 1,900 kg.