The twin satellites in NASA's STEREO mission will act like a pair of human eyes to create a three-dimensional vision of the Sun.

Credit: NASA

Related articles

• NASA captures Sun in 3-D
• Massive solar eruptions to be captured in 3D
• Space: sunny with localised storms
• Messenger makes a pass at Venus
• Hubble given a new lease on life

CAPE CANAVERAL: NASA today launched the STEREO international mission to study the Sun for the first time in three dimensions, sending twin solar observatories into orbit.

The two-year Solar Terrestrial Relations Observatory (STEREO) mission will be the first to view the Sun from two separate vantage points outside Earth's orbit.

The nearly identical satellites will act like a pair of human eyes, each picking up data that will be correlated, with data from observatories on the ground and in low-Earth orbit, into a third-dimension vision of the Sun's eruptions and their impact on Earth.

A three-stage Boeing Delta II rocket carrying the observatories lifted off from Cape Canaveral Air Force Station at 6:52 am Sydney time, the last minute of a 15-minute launch window that opened at 6:38 am.

The twin spacecraft, each about the size of a golf cart and weighing some 620 kilograms, separated without problem from the rocket after launch, a spokesman for the U.S. space agency NASA said.

Once in orbit, the observatories, each equipped with 16 instruments, will provide the first images in three dimensions of the Sun and its corona. NASA said it expected to have the first 3-D images of the Sun in mid-December.

"We are at the dawning of a new age of solar observations," Russ Howard of the Naval Research Laboratory said. "We're going to be viewing things in a new dimension for us."

Howard said STEREO would have an unprecedented "broadside" view of the entire relationship between the Sun and Earth, which are some 150 million kilometres apart.

Scientists hope the mission will provide insight into solar activities such as coronal mass ejections (CMEs), the most violent explosions in the solar system.

When aimed at Earth, these billion-tonne eruptions of the sun's corona spew intense radiation, severely disrupting the Earth's environment and endangering astronauts and scientific spacecraft.

Information gleaned on the origins and behaviors of CMEs would allow more accurate forecasting, which would improve planning for space missions as well as over-the-pole flights, satellite communications and video transmissions.

At first the twin observatories will be placed in a highly eccentric Earth orbit, NASA said. After a few weeks, the two spacecraft - named "A", for "Advance", and "B", for "Behind" - are expected to drift slowly apart but stay relatively close to each other as they line up for their close encounter with the Moon about one month into the mission.

"This is when the relatively small distance between the two spacecraft makes all the difference," the space agency said on its website. NASA will use the Moon's gravity like a pinball flipper to send them into opposite and slightly distinct orbits around the sun.

Behind will be flung completely away from Earth, and will become a satellite of the Sun, while Ahead will curve back to fly past the Moon a second time six weeks later, and be flung out in the opposite direction. Ahead will orbit ahead of the Earth in its rotation around the Sun and the Behind will follow Earth's orbit.

The total cost of the mission is US$550 million, NASA said. Scientists from four European countries - Belgium, Britain, France and Germany - are participating in the mission: