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 Flight controllers at the Johns Hopkins University Applied Physics
Laboratory in Maryland earlier estimated that Messenger, traveling
at more than 8,700 mph (14,000 kph), would hit the ground near
Mercury’s north pole at 3:26 p.m. EDT (1926 GMT).
Messenger, with no more fuel to maneuver, fought the downward push
of the sun's gravity until it impacted the planet's surface. It
likely gouged a 52-foot-wide (16 meter) crater into Mercury's 's
scarred face
During its final weeks in orbit, Messenger relayed 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, made the first close-up studies of Mercury since
NASA’s Mariner 10 spacecraft flew by the planet three times in the
mid-1970s. It arrived at Mercury in 2011 after a circuitous six-year
journey. During its 4,104 orbits of Mercury, Messenger made
surprising detections of potassium, sulfur and other volatiles on
the planet’s surface that presumably should have evaporated due to
the planet’s high temperature. Mercury’s average surface temperature
is 332 degrees Fahrenheit (167 degrees Celsius), with daytime highs
of 801 degrees Fahrenheit (427 degrees Celsius.)
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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.
It also found evidence of past volcanic activity and signs the dense
and shrinking planet has a liquid-iron core.
"It's mind-boggling how much we have accomplished,” Messenger
scientist Deborah Domingue, with the Planetary Science Institute in
Tucson, Arizona, said in a statement. “There is such a feeling of
satisfaction."
Europe and Japan are partnering on a follow-on mission to Mercury,
called BepiColombo, due to launch in 2017.
(Editing by Ted Botha)
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