Canada’s Radarsat-2 Earth observation satellite will be launched by a Russian Soyuz rocket instead of a Boeing Delta 2 launch vehicle following a Boeing determination that the rocket could give the satellite a rougher ride into orbit than originally thought, Boeing and MacDonald, Dettwiler and Associates (MDA) officials said.

Vibrations caused by the shutdown of the vehicle’s Rocketdyne RS-27 main engine — which were thought to result in a short, quickly dissipated shock — in fact, can accelerate as they move up the vehicle, officials said.

Called a sine vibration, the phenomenon has forced Boeing’s Delta 2 engineers to recalculate rocket-satellite compatibility since it was first discovered in early 2004 following a NASA-commissioned study of Delta 2’s launch environment.

Boeing and Radarsat-2 prime contractor MDA of Richmond, British Columbia, had contracted in 2000 for a Delta 2 launch of Radarsat-2 in 2003. Radarsat-2 subsequently encountered multiple component delays that in turn delayed the launch. The 2,200-kilogram Radarsat-2 subsequently was scheduled for launch in 2005, then in mid-2006, aboard a Delta 2 launched from Vandenberg Air Force Base, Calif.

Boeing officials said that export-control issues delayed a full notification to MDA of the sine-vibration problem. That delay, plus the continued slip of Radarsat-2’s planned completion date, ultimately led Boeing and MDA to agree to terminate the contract.

The satellite now is scheduled for a December launch aboard a Soyuz vehicle from Russia’s Baikonur Cosmodrome in Kazakhstan. Radarsat-2 is designed to operate from a sun-synchronous orbit at 798 kilometers in altitude for at least seven years and will succeed the current Radarsat-1 spacecraft, which is past its scheduled retirement date.

Bruce Stott, MDA deputy general manager for space programs, said Radarsat 2’s design has not changed since the 2000 contract and that it would have taken MDA too long to adjust the satellite to the new Delta 2 vibration limits to stick with the vehicle.

“Boeing and MDA worked hard to find a way around this,” Stott said Jan. 13. “But at the end of the day, they could not change the vehicle and it would have been incompatible with our program schedule to do what was necessary to chance the spacecraft. So we decided to go our separate ways.”

MDA issued a statement Jan. 12 announcing a December 2006 launch date for Radarsat-2 without naming the vehicle that will perform the launch. Keyzer confirmed the choice of Starsem and Soyuz.

Boeing officials said no other satellite has had to switch vehicles since the 2004 discovery of the nature of the vibration that had long been noticed during Delta launches. But with the passage of years between the contract signing and now, the commercial-launch landscape has changed.

A Soyuz vehicle can be purchased for around $40 million, whereas a Delta 2 rocket is commonly priced at around $60 million.