MESSENGER (MErcury Surface, Space ENvironment, GEochemistry, and Ranging) is the first spacecraft sent to orbit Mercury. The first to bring back new data from Mercury since Mariner 10, the spacecraft was built for a wide range of scientific goals.

MESSENGER IllustrationThe MESSENGER spacecraft had a 12-month primary mission that mapped the surface of Mercury over two of its solar days. The highly elliptical orbit allowed for a global map to be made of the planet, with particular focus on the geology and composition of the giant Caloris impact basin. The 12-month extended mission beyond that allowed for better studies of the environment around Mercury as the solar maximum approaches. As of March 2013, 100% of the surface of Mercury was mapped by the spacecraft, a huge achievement.

MESSENGER’s 6 broad scientific questions are:

  • Why is Mercury so dense? Its metal-rich core comprises over 60% of the mass of the planet. How did it get this way?
  • What is the geologic history of Mercury? With the first full map of the surface, planetary geologists can explore the history of the many surface features, from crater chains to wrinkle ridges, piecing together a story of Mercury’s past.
  • What is the nature of Mercury’s magnetic field? Mercury has a global magnetic field similar to the Earth, but off-axis from its rotation by 20 degrees.
  • What is the structure of Mercury’s core? By taking precise altimeter measurements and using the planet’s own gravity, MESSENGER can determine how much of the core is molten.
  • What are the unusual materials at Mercury’s poles? Some polar craters are permanently shadowed but highly reflective to radar. What lurks in these shadows?
  • What volatiles are important at Mercury? Mercury’s thin exosphere is a product of the planet’s proximity to the Sun. MESSENGER will study it in greater detail as solar maximum approaches.

See the MESSENGER Mission page for more information!

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