NASA Probe to Crash Into Mercury in 2 Weeks' Time

NASA’s MESSENGER spacecraft is in the final days of an unprecedented and unexpectedly long-lived, close-up study of the innermost planet of the solar system, with a crashing finale expected in two weeks.

Out of fuel, the robotic Mercury Surface, Space Environment, Geochemistry and Ranging, or MESSENGER, probe on April 30 will succumb to the gravitational pull of this strange world that has been its home since March 2011. The purpose of the mission, originally designed to last one year, is to collect detailed geochemical and other data that will help scientists piece together of how Mercury formed and evolved. Mercury is one of four versions of rocky planets in the solar system, along with cloud-shrouded Venus, life-friendly Earth and dry, cold Mars.

After two mission extensions, scientists got a six-week bonus run after engineers figured out a way to vent helium used to pressurize the spacecraft’s fuel tank as a way to gain some altitude. MESSENGER’s last boost, scheduled for April 24, will hike the probe’s altitude from about six miles to about 12 miles above the planet’s surface, adding another six days -- roughly 40 orbits -- for studies.

"MESSENGER is going to create a new crater on Mercury sometime in the near future ... let's not be sad about that," NASA associate administrator John Grunsfeld said Thursday, kicking off an event to celebrate the mission's science results.

MESSENGER’s last days have been among the mission’s most rewarding, including details on the surprising discovery that Mercury, despite being so close to the sun, has ice inside craters near its poles, regions that are never directly exposed to sunlight.

Analysis of images shows a dark, possibly carbon-rich material overlying ice in one crater, named Fuller after architect Richard Buckminster Fuller. That could have happened when an icy comet or carbon-rich asteroid smashed into Mercury.

MESSENGER also has found bright spots inside some craters, which turned out to be shallow, recently formed depressions known as hallows.

"Hallows are a land form we didn't expect. They are some of the youngest features on the planet, and this speaks to some unstable material whose identity we are still working out," said MESSENGER's lead scientist Sean Solomon, with Columbia University.

Similar features have been found on the water-rich dwarf planet Ceres, which is about to become the focus of detailed studies by NASA’s orbiting Dawn spacecraft.

Read more at Discovery News