Scientists at the European Space Agency (ESA) are anxiously awaiting the results of an investigation into the explosion of an Ariane 5-ESCA rocket over the Atlantic just 3 minutes after its launch from the spaceport in Kourou, French Guiana, on 11 December. The ESA's most daring mission to date--a rendezvous with a comet by an unmanned spacecraft called Rosetta--depends on the successful launch of a similar Ariane rocket from Kourou on 12 January.
"The loss of Rosetta would be the unthinkable," says Marcello Coradini, head of solar system missions for ESA. According to a statement today from the French rocket company Arianespace, ESA can relax because Rosetta will be taken aloft by an older Ariane 5 version that has a long track record of success. The larger Ariane 5-ESCA was designed for the 10-ton payload of two French commercial satellites lost in the accident. Arianespace suspects that the fault occurred in the newly designed upper stage of the rocket.
In spite of the ongoing investigation, Rosetta is still scheduled for its January launch, says Coradini. "Everything is ready to go." However, ESA is exploring later launch dates in case fault is found in a component that Rosetta's rocket shares with the Ariane 5-ESCA. Gerhard Schwehm, ESA coordinator of the Rosetta team, adds that backups exist of Rosetta's critical components, should the worst happen.
If Rosetta is successfully launched, it will orbit Earth twice and Mars once before meeting up with Comet Wirtanen, an ancient 1.2-km-diameter chunk of ice that circles the sun every 5.5 years. "No one has tried to land on a comet before," says Schwehm. The 21 experimental modules within Rosetta will probe Wirtanen's hard core and its dusty halo, looking for signs of life and clues to the early origins of the solar system.