2 Double vision
The two STEREO spacecraft will generate 3D images of coronal mass ejections by virtue of their different vantage points in space. They are due to be launched together on a Boeing Delta II rocket from Cape Canaveral in Florida at the end of this month (although this date may slip if a battery cannot be found to power the rocket's obligatory self-destruct mechanism). Once released, the spacecraft will fly in an eccentric orbit around the Earth, bringing them close to the Moon about two to three months after take-off. At this point the satellites will be just far enough apart that the Moon's gravity can fling them off in completely different directions - one will enter into an orbit around the Sun and the other will curve back on itself to fly past the Moon again six weeks later before entering into a solar orbit. The end result is that one spacecraft ends up in a solar orbit slightly ahead of the Earth while the other trails behind the Earth. Image: NASA