U.S. space agency NASA said its 11-year-old MESSENGER spacecraft ran out of fuel and crashed into Mercury Thursday, creating a 16-meter-wide crater on the planet's scorched surface.
"A NASA planetary exploration mission came to a planned, but nonetheless dramatic, end Thursday when it slammed into Mercury's surface at about 8,750 mph (3.91 kilometers per second)," NASA said in a statement.
"MESSENGER's lonely demise on the small, scorched planet closest to the sun went unobserved because the probe hit the side of the planet facing away from Earth."
Both ground-based and space-based telescopes were not able to capture the moment of the impact, which occurred, as anticipated, at 3:26 p.m. EDT (1926 GMT), the space agency said.
Mission control confirmed the end of the operations just a few minutes later, at 3:40 p.m. (1940 GMT), when no signal was detected by NASA's Deep Space Network (DSN) station in California, at the time the spacecraft would have emerged from behind the planet.
This conclusion was independently confirmed by the DSN's Radio Science team, which also was monitoring for a signal from MESSENGER.
MESSENGER was launched on Aug. 3, 2004, and began orbiting Mercury on March 17, 2011. Although it completed its primary science objectives by March 2012, the spacecraft's mission was extended twice.
During its 4,105 orbits around Mercury, MESSENGER determined the planet's surface composition, revealed its geological history, discovered its internal magnetic field is offset from the planet's center, and verified its polar deposits are dominantly water ice.
"It's mind-boggling how much we have accomplished," Deborah Domingue of the Planetary Science Institute in Arizona, who participated in the MESSENGER mission, said in a statement. "It's an era coming to a close. There is such a feeling of satisfaction, such a feeling of accomplishment, in having been a part of history. "