The STEREO mission consists of two spacecraft orbiting the Sun, one moving a bit faster than Earth (A-ahead) and the other a bit slower (B-behind). In the time since the STEREO spacecraft entered these orbits near the beginning of 2007 they have been slowly separating. In Feb. 2011 they reach the point at which they are on opposite sides of the Sun and can observe the entire far side of the Sun.
Wow! After all these years, we have a complete picture of the sun. I find it a little breathtaking. I do hope the 2012'ers can now feel certain there are no planets hiding on the opposite side of the sun from Earth.The more important, of course, is the increase in ability.Take for instance the inability to continue broadcasting from the Mars orbiter last week. If we had used a system that reached the entire circumference, it would not have happened.
In case you missed it, by the way, the orbiter went behind the sun to us. When this happened, the communication had to be stilled because otherwise we would be taking a chance that interference from the Sun would interrupt a part of the signal from us to the orbiter. If it would have killed all instructions, no big deal. Obviously, if it didn't kill any signal, same thing. But, kill a part and anything could happen. Ergo, shut it down. I believe we will find innumerable ways to utilize this ability. (we always do).
Anyway, this is my first try at video, so, enjoy(all 1 or 2 of you)