The 7.5-meter (24-foot) tall, two-meter (six-foot) diameter motor, featuring a carbon epoxy filament wound casing, delivered more than 100 metric tons of thrust, burning some 24 metric tons of solid propellant in 75 seconds.

Engineers gathered numerous data during the test and now are analyzing the figures to improve technical knowledge of the motor's behavior and refine the launcher's future performance, ESA said in a news release.

Also tested during the firing were various sub-systems, including a thrust-vector-control system that will steer the motor's nozzle to provide flight control. The next step is to proceed with the critical design review, at which stage the engine's technical characteristics will be finalized, the release continued.

Built by Avio in Colleferro, near Rome, the Zefiro 23 motor will be the basis for the second stage of ESA's Vega launcher. Engineers performed the first firing test with the third stage motor � the Zefiro 9 � in December 2005.

Conducted on behalf of ESA's Vega development program, the latest two firing tests followed three static firings of the Zefiro 16 demonstrator in 1998, 1999 and 2000. Both the Zefiro 23 and Zefiro 9 will undergo an additional ground firing test each to complete their development and qualification.

"The Zefiro 23 is one of the largest composite casing solid rocket motors ever test fired in Western Europe, said Antonio Fabrizi, ESA's director of launchers, "but it will be dwarfed shortly, when we will fire Vega's first stage motor, the P80, with its 88 tons of propellant, in Kourou, French Guiana, in November."

That first Vega flight currently is scheduled for the end of 2007.

Under development since 1998 with the support of seven ESA Member States - including Italy, France, Belgium, Switzerland, Spain, the Netherlands and Sweden - ESA's Vega small-satellite launcher is an all-solid three-stage vehicle with a liquid-fueled injection module.

ELV SpA, a joint venture of Avio and ASI, the Italian Space Agency, was delegated the responsibility for Vega development. CNES, the French space agency, holds similar responsibility for the P80 first stage.

Vega is designed to loft single or multiple payloads to orbits up to 1,500 kilometers (930 miles) in altitude. Its baseline payload capability is about 1,500 kilograms (3,300 pounds) to a circular 700-kilometer (435-mile) high sun-synchronous orbit, but it can also loft satellites from 300 kilograms (660 pounds) to more than 2 metric tons (2.2 tons), as well as piggyback micro-satellites.

This range of performance covers the needs for multiple applications in the fields of remote sensing, environmental monitoring, Earth science, space science, fundamental science and research and technology for future space applications and systems.

Once qualified, Vega will be marketed and operated by Arianespace, as a complement to Ariane 5 and Soyuz, and will address the small-satellite launch market.

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