In a little over 12 hours, the spacecraft MESSENGER will finally be orbiting the planet Mercury. It’s been a long trip: MESSENGER launched way back in August of 2004 and has spent the intervening time doing flybys of Earth, Venus and Mercury. To date it has gone almost 4.9 billion miles. The problem with orbiting Mercury is that it’s so close to the sun and that means it is going very fast, so the spacecraft had to boost its orbital speed while shrinking the size of its orbit until it matched Mercury. Rather than launch tons of fuel, the engineers on MESSENGER figured out a way to adjust the orbit using flybys. And just to make things interesting, remember that MESSENGER has to do all of this while keeping its ceramic heat shield pointed toward the sun.

One side effect of MESSENGER’s first flyby of Earth was this fantastic video. I have to tell people when I show them that this is really our planet, it’s not CGI or anything:

http://www.youtube.com/watch?v=ljh8_q-DmuI

MESSENGER has already changed our understanding of Mercury, revealing parts of the planet that had never been seen before, but today the real mission starts. I’ll post the first pictures once they start coming down!