Managers of Europe’s Venus Express orbiter plan to ship the satellite to Russia’s Baikonur Cosmodrome Aug. 6 on the assumption that Russia’s Soyuz rocket family, which is now grounded, will be cleared for flight in time for a planned October launch.
The June 21 failure of a Russian Molniya -M rocket, launched from northern Russia’s Plesetsk Cosmodrome, forced the suspension of Soyuz launches because Soyuz and Molniya have many common design elements. A board of inquiry is investigating the causes of the failure.
Venus Express, in final testing here by prime contractor EADS Astrium, is scheduled for launch Oct. 26. The satellite is an example of what the European Space Agency (ESA) hopes will become a common practice of reusing hardware on more than one satellite, with the savings applied to missions that otherwise would be out of the agency’s financial reach.
Venus Express was approved by European science managers in late 2002. Its budget of 220 million euros ($ 262 million) includes 82.4 million euros to EADS Astrium for the satellite construction and integration of the instruments and about 37 million euros to the French-Russian Starsem organization for the Soyuz launch.
The remaining funds are paying for ESA’s project-management team, about two years of operations once the satellite reaches Venus orbit and the seven payload instruments.
Michel Bouffard, EADS Astrium director of Earth observation and science, and ESA Venus Express Project Manager Don McCoy said here July 6 that Venus Express’ development history has been unusual.
Astrium, which is prime contractor for ESA’s Mars Express orbiter, proposed to the agency that the Mars Express platform could be rebuilt at low cost for another mission. ESA’s Science Program Committee subsequently selected a Venus orbiter and a contract was signed with Astrium in October 2002.
Most ESA science missions are conceived by science teams, with the agency then seeking industrial proposals to build the satellite. “We turned that process on its head,” Bouffard said. “And 34 months after the contract’s signing, we will be ready to ship.”
Josian Fabrega, Venus program manager at Astrium, said about 85 percent of the hardware on the Venus Express satellite is reused from the Mars Express satellite.
The reuse philosophy goes beyond the Astrium-built satellite skeletal structure. Three of the seven observing instruments on Venus Express are onboard Mars Express as well, and three others were borrowed from ESA’s Rosetta comet-chaser satellite, launched in March 2004.
“What we are aiming for at the agency is a line of products that permit us to reuse hardware,” McCoy said.
Individual ESA member states are responsible for providing the payload instruments for the agency’s science satellites from their own budgets. Reusing hardware means going back to the same governments to finance a rebuild.
In the case of Venus Express, rebuilding instruments used on Rosetta or Mars Express put a strain on the budgets of some of the national agencies. ESA ultimately was forced to step in and provide part of the funding.
Building a second copy of any given space-qualified instrument affords savings. But to maximize the economies, the order should be made while the teams that assembled the first copy are still together. That was done in the case of Venus Express.
“There was no rupture of the team working on Mars Express. They were moved without interruption onto the Venus Express program,” Bouffard said. “We had a nearly 100 percent overlap between the two programs.”
The one significant change in hardware between Mars Express and Venus Express is the solar arrays. To avoid degradation from the intense heat of Venus — its proximity to the S un, and the fact that the planet’s surface is highly reflective of the S un’s heat — the Venus Express satellite carries solar arrays that are interlaced with aluminum strips.
The aluminum is designed to reflect the sun’s rays and keep temperatures on board the satellite as low as possible. To reduce the effects of the heat, Venus Express will be equipped with gallium arsenide solar cells instead of the silicon-based cells used on Mars Express.
Hakan Svedhem, ESA science manager for Venus Express, said the Venus Express platform will be filled to the maximum possible fuel level to assure that the satellite is able to perform a braking maneuver to enter Venus orbit.
Even with its tanks topped off, Venus Express will not have enough fuel to maneuver itself into the low circular orbit that would be ideal for surface observations.
Instead, scientists will have to live with a highly elliptical orbit that varies between 250 and 66,000 kilometers above Venus’ surface.
