NASA Messenger Probe to Crash Land Into Planet Mercury

NASA's Messenger spacecraft is expected to crash land into Mercury at a speed of more than 8,750 miles per hour [3.91 km/sec] on Thursday, and is predicted to leave a 16 meter crater in its surface, its final contribution to scientific discovery.

Messenger, whose name is short for MErcury Surface, Space ENvironment, GEochemistry and Ranging, is the first-ever probe to orbit the planet, and will run out of propellant, having completed a mission which began when it was launched in 2004. It traveled 4.9 billion miles [7.9 billion kilometers] — a journey that included 15 trips around the sun, during which it made several flybys: it flew by Earth once, Venus twice, and Mercury three times before entering into orbit round Mercury in March 2011.

The next probe to study Mercury, the BepiColombo mission set for launch in 2017, "will be looking for signs of this crater, and if they can make measurements of it, they will know precisely how long that region has been exposed to space," explained Sean Solomon, the principal investigator of the Messenger mission and director of the Lamont-Doherty Earth Observatory at Columbia University.

The three-meter wide Messenger is the first spacecraft to visit Mercury since the Mariner 10 performed three flybys of the planet in 1975, and the end of the mission marks "the beginning of a longer journey to analyze the data that reveals all the scientific mysteries of Mercury," said John Grunsfeld, associate administrator for the Science Mission Directorate at NASA Headquarters in Washington.

"For the first time in history we now have real knowledge about the planet Mercury that shows it to be a fascinating world as part of our diverse solar system."

This video was captured by NASA's MESSENGER spacecraft during a flyover of Mercury's north pole on June 8, 2014.

Among Messenger's key findings is compelling support for the hypothesis that Mercury harbors abundant frozen water and other volatile materials in its permanently shadowed polar craters, a discovery which allows scientists to build a picture of how the inner planets, including Earth, acquired water and some of the chemical building blocks for life.