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

The planet closest to the sun better be on its best behaviour, 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, 154 million kilometres, 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]


    Mercury is not "the hottest planet that our solar system has to offer": that prize goes to Venus. At least as far as average temperature. The average temperature on Mercury is 452 degrees Celsius, the average temperature on Venus is 464 degrees Celsius. You would be more correct to say that Mercury has temperatures higher than any planet in our solar system. The side of Mercury that is facing the sun can reach temperatures of 700 degrees Celsius; however, the side facing away from the sun at that time is very cold. So the average temperature on Mercury is lower than the average temperature on Venus, due mostly to the dense atmosphere on Venus and the total lack of atmosphere on Mercury.

      If you're going to criticize other people, and try to fool folks into thinking you're an expert you might want to get your facts straight.

      Mercury does not get 700C on the sunlit side. That's 700 Kelvin. It only gets about 425 Celsius max and only averages around 180C.

    Great job. We should appreciate them

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