Europe's small satellite launcher is on the home stretch of its protracted development, as engineers methodically check to ensure each of the Vega rocket's parts are qualified for flight.

Artist's concept of a Vega launch. Credit: ESA

The Vega is still undergoing software and electronics testing, even though its rocket motors and launch pad are nearly ready to go.

Engineers began testing the capabilities of Vega's software in July to ensure the rocket's avionics could execute a wide variety of potential missions.

"The aim of these tests, with the flight software, the avionics systems and the Vega simulator is to qualify the Vega avionics system (and) software simulating the different missions," said Stefano Bianchi, head of the Vega program at the European Space Agency.

The mission simulation testing is being conducted at a facility near Rome.

"We are simulating the missions and verifying the software with various electronic paths of the launcher," said Antonio Fabrizi, chief of ESA's launchers program. "That's the most important technical activity that is running in parallel with the completion of the qualification reviews of the systems."

Other ongoing reviews include the thrust vector control steering system, the roll control system, and the fourth stage liquid-fueled engine. Officials expect to meet those milestones before the end of this year, Bianchi said.

The mission simulations, which will continue into 2010, are the now the pacing items to wrap up Vega's development phase.

Now scheduled for its debut launch next fall, the Italian-led Vega rocket is tailored to send lightweight ESA institutional satellites into orbit. Vega's specific niche market will be Earth observation and scientific missions, according to Jean-Yves Le Gall, chairman and CEO of Arianespace.

"Vega's launch pad is ready, but the question for Vega is the development of the launch vehicle. Of course, it's a completely different project, so that has a lot to do when Vega is out of development," Le Gall said in an interview with Spaceflight Now.

The Vega rocket's maiden flight has been delayed since 2007.

Arianespace will operate the 98-foot-tall Vega rocket under a contract with ESA.

All three solid-fueled rocket stages of the vehicle have finished qualification testing. The first stage is based on a modified Ariane 5 solid rocket booster. Development of a small liquid-fueled upper stage is nearing completion.

Workers have also constructed a new mobile gantry at Vega's ELA-1 launch pad at the Guiana Space Center in Kourou, French Guiana. The site was former home of the Ariane 1, 2 and 3 rockets.

Integrated tests of the pad systems are almost finished, and then the complex will be ready to receive the first Vega rocket around the middle of next year for pathfinder fit checks.

The payload for Vega's first launch is the Italian Space Agency's Laser Relativity Satellite, or LARES, a spacecraft named ALMASat, and nine small CubeSats for European universities.

The Vega will deposit the payloads into a 900-mile-high orbit with an inclination of 70 degrees, according to Bianchi.

Five more ESA-sponsored qualification flights are planned after the maiden launch under a program called Vega Research and Technology Accompaniment.

"With these flights, we not only make a promotion of the launcher's introduction into the market, we also want to demonstrate the ability of the launcher to complete different types of missions," Fabrizi said.

The first promotional launch is being offered by ESA as a mission-of-opportunity. A payload for that flight should be selected soon.

The other developmental launches should carry operational ESA payloads, according to Fabrizi.

Bianchi said the satellites could include the ADM-Aeolus winds research mission, the three-satellite Swarm constellation to study the magnetic field, the LISA Pathfinder demo mission and the Intermediate Experimental Vehicle.

These missions will test Vega's ability to conduct a range of missions, including single-satellite launches to polar orbit, multi-spacecraft flights, a deep space mission and a re-entry demonstrator.

If ESA payloads are not available for the qualification flights, Fabrizi said the agency will open up Vega launches to European member states.

The Vega rocket will be able to lift up to 3,300 pounds to a standard 435-mile-high polar orbit, according to specifications.