STEREO blasts off from Cape Canaveral

At last!

NASA's twin solar observatory, STEREO, launched successfully last night, blasting off from Cape Canaveral just before 9pm, local time. The launch was originally scheduled for August, but was put back several times.

The STEREO mission (short for Solar TErrestrial RElations Observatories) will provide the raw material researchers need to build the first ever three dimensional images of the sun.

"The stunning solar views the two observatories will send back to Earth will help scientists get a better understanding of the sun and its activity than we've ever been able to obtain from the ground or any of our other missions," said Nick Chrissotimos, STEREO project manager at NASA's Goddard Space Flight Centre.

The mission is comprised of two virtually identical golf-cart sized satellites. They were sent on diverging paths orbiting the sun, NASA confirmed, just 63 minutes after reaching orbit. NASA also confirmed that the solar panels that will power each observatory had unfurled without any problems.

The craft are designed to study solar activity. They will be watching for solar flares and coronal mass ejections, the huge eruptions of solar material than can play havoc with Earth and space-based equipment. Scientists hope that better monitoring of the sun's surface will help scientists spot the early warning signs of such events.

Current observatories can study these eruptions and ejections, but can only do so in one dimension. STEREO will be better able to track material heading to Earth because it will have two views of any eruption or flare.

This also means it will give Earth more warning of incoming floods of solar material. Satellites in orbit can be put into safe mode in time to avoid being overloaded, and power grids on Earth can also be protected from the solar storms.

Over the next two weeks, NASA engineers will make sure the STEREO craft are working as they should. They will fly to a point just beyond the moon's orbit, where after three months, their orbits will be synchronised to encounter the moon, to set the craft on their very different orbital paths. It is the first NASA mission to use the lunar gravity in this way.

The "A" observatory will use the moon's gravity to redirect it to an orbit "ahead" of Earth. The "B" observatory will encounter the moon again for a second swing-by about one month later to redirect its position "behind" Earth.

It is this offset between the observatories, just like the offset between our eyes, that will make it possible to build three dimensional pictures of the sun. ®

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