NASA spacecraft to smash into Mercury
NASA's pioneering Messenger spacecraft is expected to end its four-year study of the planet Mercury this Thursday by crashing into the planet's surface, scientists said.
Out of fuel to maneuver, Messenger is being pushed down by the sun's gravity closer and closer to the surface of Mercury.
Flight controllers at the John Hopkins University Applied Physics Laboratory in Maryland predict that Messenger, traveling at more than 14,000 kph, will hit the ground near Mercury's north pole later this evening at 7:25 pm.
The impact will add a new 52-foot-wide (16 meter) crater to the planet's scarred face.
During its final weeks in orbit, Messenger has been relaying more details about the innermost planet of the solar system, which turns out to have patches of ice inside some of its craters, despite its sizzling location more than twice as close to the sun as Earth.
"We've been concentrating on getting as much of the data down on the ground," lead researcher Sean Solomon, with Columbia University in New York, wrote in an email.
"We will have years to think about the meaning of the measurements."
Messenger, or the Mercury Surface, Space Environment, Geochemistry and Ranging craft, has been making the first close-up studies of Mercury since NASA's Mariner 10 spacecraft made three flybys in the mid-1970s.
Europe plans to launch a follow-on mission to Mercury in 2017.
Messenger's key discoveries include the detection of elements such as potassium and sulfur on the planet's surface, volatiles that presumably should have evaporated due to the planet's high temperature.
Mercury's average surface temperature is 167 degrees, with daytime highs of 427 degrees.
Messenger also confirmed the existence of ices and other materials, possibly even carbon-based organics, on the floors of craters where sunlight never shines.
During its final days, Messenger attempted to peer directly down into targeted craters, Solomon said.