An artist's concept of the Fregat upper stage carrying two Cluster 2 satellites into space. Photo: ESA

A new Russian rocket that will launch a series of European science probes over the next few years passed its final examination on Monday with a successful test flight.

The 90-minute mission began when the Soyuz rocket lifted off at 1828 GMT (1:28 p.m. EST) from complex 6 at Baikonur Cosmodrome, Kazakhstan.

At the center of the test was the new Fregat upper stage, which will loft the four European Space Agency's Cluster 2 satellites during a pair of launches this summer and the Mars Express probe in 2003.

The Fregat carried a metallic cylindrical structure, nicknamed "Dumsat" on Monday. The payload mock-up was built to accurately simulate two Cluster 2 satellites. "Dumsat" also featured a suite of sensors and meters to tell engineers what the launch was really like by measuring the mechanical, thermal and acoustical environments atop the rocket.

Monday's test flight was a complete dress rehearsal for the upcoming Cluster 2 launches, following the same trajectory and timeline. The Fregat also proved it could be restarted in space and complete orbital maneuvering, officials said.

About nine minutes after liftoff, the Soyuz's first three stages had each completed their firings and dropped away. The Fregat upper stage's S5.92 engine then ignited for a three-minute firing to achieve a near-Earth parking orbit.

Once arriving in the preliminary orbit, Fregat and attached "Dumsat" began a quiet coast period through space.

A second Fregat firing followed just over 75 minutes into flight to deliver the dummy payload into a highly elliptical orbit like the Cluster 2 satellites will require.

Fregat later completed a simulated deployment of its mock-up cargo about 90 minutes after launch.

An artist's concept of the four Cluster 2 satellites in space studying the solar wind. Photo: ESA

The Fregat successfully completed its first validation flight on February 9. It was developed using flight-proven technologies and propulsion systems flown on historic Russian lunar and deep space missions.

With the upper stage now qualified, the stage is set for the Cluster 2 launches on June 15 and July 13 from Baikonur.

The Cluster 2 satellite quartet are four replacements for the same research craft lost in the failed inaugural flight of Ariane 5 in 1996.

The spacecraft will fly high above the planet to probe the interaction between the supersonic stream of charged particles from the sun, called the solar wind, and Earth's magnetosphere.

Understanding the affects the solar wind has on Earth is important to scientists because it can disrupt communications and power on the planet and harm satellites in space.

Monday's launch was the eighth managed by Starsem, a joint Russian and French venture founded in 1996 to commercially market the Soyuz rocket.

Starsem was created by the Russian Aviation and Space Agency and Russia's Samara Space Center, Europe's Arianespace and Aerospatiale Matra of France.