Spacecraft Set for Death Plunge Into Mercury

The MESSENGER spacecraft -- which stands for MErcury Surface, Space ENvironment, GEochemistry, and Ranging -- will end its run and dive into Mercury at 3:26:02 p.m. ET today, the U.S. space agency said.

The spacecraft is expected to crash onto the planet's surface at a searing 8,750 miles per hour -- fast enough to carve out a crater 52 feet wide.

Its mission was initially only supposed to last one year, but since it was operating well and returning interesting data and discoveries, scientists extended its life as long as they could.

MESSENGER's key finding, in 2012, was a thick coat of ice in Mercury's polar regions, providing "compelling support for the hypothesis that Mercury harbors abundant frozen water and other volatile materials in its permanently shadowed polar craters," NASA said.

"For the first time, scientists began seeing clearly a chapter in the story of how the inner planets, including Earth, acquired water and some of the chemical building blocks for life," the agency said in a statement.

Scientists believe that the closest planet to the sun likely got its water when comets and volatile-rich asteroids made impact, sometime in history.

MESSENGER was launched in 2004 and traveled for more than six years before it finally began orbiting Mercury on March 18, 2011.

Once the unmanned probe runs out of propellant, it will no longer be able to fight the downward push of the Sun's gravity and will fall, striking the planet at more than 8,750 miles per hour (3.91 kilometers per second) on the side of the planet facing away from Earth.

Read more at Discovery News