Mercury Didn't Have A Satellite, So We Gave It One

The planet closest to the sun better be on its best behavior, because we're watching it. As of last night NASA's Messenger probe is the first man-made satellite ever to orbit the planet Mercury. What do we hope to find?

After a journey of nearly seven years, 96 million miles, and two fly-bys, NASA's Mercury craft has finally parked itself in orbit around the hottest planet our solar system has to offer. Mercury was launched in August 2004. On January 14, 2008, Mercury became the second man-made craft to successfully reach Mercury, the first being the Mariner 10 way back in 1975. In 2009 it performed another fly-by of the planet, probably just showing off.

Last night the craft fired its thrusters and made history.

So now we've got a satellite orbiting Mercury. What are we going to do with it? The answer lies in the satellite's name. Messenger is actually an acronym for MErcury Surface, Space ENvironment, GEochemistry and Ranging, a forced acronym if I've ever seen one. Mercury was the messenger for the gods, you see, so they had to come up with something better than Mariner.

Messenger is tasked with mapping the surface of the planet, determining its chemical composition, and determining the strength of the magnetic field of the planet.

Over the next few weeks, Messenger will busy itself sending diagnostic data back to the folks at NASA as it travels along its 12-hour elliptical orbit, protected by a ceramic heat shield to protect it from a sun 11 times brighter than it shines on earth. Then the science begins.

Messenger Principal Investigator Sean Solomon, of the Carnegie Institution of Washington, said Messenger has already made history. "Mercury's secrets, and the implications they hold for the formation and evolution of Earth-like planets, are about to be revealed," he said.

After Messenger Spacecraft's Successful Orbital Burn, Mercury Now Has Its First-Ever Satellite [Popular Science]