The first of two new international science satellites was launched from a Chinese launch pad Monday, ending that nation's most active year in space and opening the next chapter in learning about the complicated relationship between Earth and our Sun.

The Double Star project consists of two satellites -- one in equatorial orbit and the other in polar orbit. Credit: Chinese National Space Administration

The Double Star 1 satellite darted from its secluded pad at southwestern China's Xichang launch center at 1906 GMT (2:06 p.m. EST), or early morning at the site. The three-stage Long March 2C booster delivered the 726-pound spacecraft into its high-wire orbit about 12 minutes after liftoff.

The orbit was the highest ever for a Chinese satellite -- with a targeted low point of 550 kilometers, a high point of over 66,000 kilometers, and an inclination of 28.5 degrees.

The launch had been delayed from Saturday due to a malfunction with the rocket's third stage detach mechanism, which was removed and replaced to allow the mission to go ahead as planned 48 hours later.

The Double Star satellites will operate for at least 18 months studying Earth's magnetosphere, where charged particles in the solar wind are caught by Earth's protective magnetic bubble and begin to affect the environment in ways in which scientists have yet to fully understand.

The second half of the fleet will be lofted into space no earlier than next June aboard another Chinese rocket -- this time into an elliptical polar orbit.

Europe has provided a total of eight instruments to the program, while China is responsible for another eight. Each spacecraft include a different suite of experiment payload packages.

The first -- now in space -- features three experiments from China, three from the United Kingdom, and one each from France and Austria. The second includes five Chinese instruments and three from Europe. All but one of the eight European payloads on the project are identical to those used in the Cluster program.

The pair will also work together with Europe's Cluster satellite quartet launched in 2000 to investigate the interaction between our home planet and charged particles swept up in the solar wind that is constantly ejected from the Sun at a speed of about 250 miles per second.

Although the general goals of ESA's growing constellation are altogether the same, each of the Double Star craft has specific tasks and are assigned to different types of orbits.

Monday's satellite will focus on the injection of charged particles into the leading side of the magnetosphere ahead of the planet as it orbits around the Sun, in addition to the long magnetic tail behind Earth, where particles are trapped and pulled toward the polar regions in a process called reconnection.

The second launch due in June will loft a polar-orbiting craft with a slightly different load of instruments to look at the dynamic processes taking place over Earth's poles as well as auroral activity.

"We hope it will be possible to make coordinated measurements with both Cluster and Double Star," said Cluster project scientist Philippe Escoubet. "For example, we would hope to carry out a joint exploration of the magnetotail, a region where storms of high energy particles are generated. When these particles reach Earth, they can cause power cuts, damage satellites, and disrupt communications."

With all six satellites working together in strategically-selected orbits to provide valued data, this will be the largest satellite system to ever collectively study the magnetosphere with common instrumentation, said ESA Double Star project manager Bodo Gramkow.

"This configuration is expected to enhance the scientific return significantly, in particular the location of geomagnetic substorm triggering can be addressed by this," Gramkow and Escoubet said via e-mail Monday from Xichang. "The additional two satellites are such not only increasing the sheer data volume, but also will provide higher valued data at the right locations of scientific interests."

The Double Star mission emblem. Credit: ESA

The Chinese government first approved the Double Star program in late 2000, and Europe was brought into the project in an historic cooperation agreement signed in July 2001.

ESA has agreed to invest roughly $10 million into the program, providing for eight science instruments, data acquisition during passes over a ground station in Spain, and for science operations management. China is responsible for the launch, spacecraft operations, and for the lion's share of ground station passes.

Officials are pleased with the cooperation that has developed between ESA and China, dating back over a decade with significant Chinese contributions to the Cluster program.

"The cooperation with a European team resident in China for about 6 months resulted in a very fruitful mutual exchange and in particular helped to bridge the significant cultural and language difficulties," Gramkow and Escoubet told Spaceflight Now.

"Both ESA and Chinese authorities are looking forward to increase future cooperation in both scientific as well application programs, as a first result the recent agreement on the Galileo program can be named as a concrete example."

"Double Star is a win-win project. Not only will European scientists participate in a new mission, at a very low cost, but they will also see an increased scientific return from the four ESA Cluster satellites. Chinese scientists will equally benefit of this, since they already participate in the Cluster mission. These are the great advantages of an historic international collaboration," ESA science director David Southwood said.