Ariane 5 Launch Of Rosetta Satellite Remains In Limbo

A second review panel is assessing the Ariane 5 rocket before it is cleared to launch the European Space Agency’s (ESA) Rosetta scientific satellite.

That mission needs to occur by month’s end for the satellite to rendezvous with Comet Wirtanen, industry officials said. The Rosetta spacecraft will be the first to undertake the long-term exploration of a comet at close quarters.

The rocket has been cleared for launch by the Arianespace review board that issued findings last week on the Dec. 11 failure of an Ariane 5 to launch satellites into orbit. The panel concluded that the failure was the result of hardware that only is on the 10-ton version of the Ariane 5 and not the basic Ariane 5 model that will be used to launch the Rosetta satellite.

Specifically, the Arianespace-led inquiry board concluded that the Dec. 11 launch failure was caused by a leak in the Vulcain 2 engine nozzle’s cooling circuit, followed by a critical overheating of the nozzle. The basic Ariane 5 uses the Vulcain 1 engine. After reviewing operating data from the Vulcain 1 engine, the inquiry board concluded that there was no problem with the functioning and resistance of its nozzle.

Awaiting Approval

A decision about a new launch date for the Rosetta mission is expected by Jan. 14.

The Rosetta mission has been in the planning stages for years and holds great significance for astronomers. ESA’s Rosetta spacecraft will be the first to orbit and land on a comet.

For the Rosetta to keep its planned rendezvous during 2012 with Comet Wirtanen, the launch must occur no sooner than Jan. 12 and no later than the end of the month, ESA officials said. The timing for the interplanetary mission’s launch window is much more rigid than for satellites that orbit the Earth.

To send a spacecraft from Earth to a planet or a comet that follows a different path through space is highly complicated, ESA officials said.

Prior to reaching the comet, Rosetta must complete a series of fly-bys of planets to gain an energy boost by taking advantage of their gravitational pull. The spacecraft is due to pass by Mars in August 2005, then carry out high-speed fly-bys of the Earth in November 2005 and November 2007, ESA officials said.

Unless each planetary fly-by is completed on time, the spacecraft will miss later ones. If the mission began after Jan. 31, Rosetta would be unable to reach the target comet, ESA officials said.

–Paul Dykewicz

(Suzy Chambers, Arianespace, 202/628-3936; Franco Bonacina, ESA, 33 (0) 1 5369 7155)