|
 The Mercury Surface, Space ENvironment, GEochemistry, and Ranging,
or Messenger, probe has been circling the innermost planet of the
solar system for more than four years, the first close-up studies of
Mercury since NASA’s Mariner 10 spacecraft made three flybys in the
mid-1970s.
Out of fuel and losing altitude, Messenger is expected to make a
high-speed crash near the planet’s north pole at around 3:25 EDT on
April 30, flight controllers told reporters during a webcast news
conference.
“The spacecraft will pass behind the planet, out of view from the
Earth, and will just not emerge again,” said Daniel O’Shaughnessy,
systems engineer with Johns Hopkins University Applied Physics
Laboratory, which operates the spacecraft.
The impact at 8,724 miles per hour (14,040 km per hour) will leave a
fresh crater, roughly 52 feet (16 meters) in diameter, that should
serve as an interesting reference point for a follow-on European
spacecraft called BepiColombo, which is due to arrive in 2024.
The crater may help scientists learn more about the planet’s
unexpectedly fast weathering processes, one of dozens of Messenger's
finding.
Topping the lead scientist’s list of Messenger discoveries is the
detection of elements such as potassium and sulfur on the planet’s
surface, volatiles that should have evaporated under the presumably
scorching conditions 36 million miles (58 million km) from the sun
where Mercury formed and orbits today. Earth, by comparison, is
about 93 million miles (150 million km) from the sun.
[to top of second column]
|
Messenger also confirmed the existence of ices and other materials,
possibly even carbon-based organics, on the floors of craters where
sunlight never shines.
As it makes its final descent toward the planet's surface, Messenger
will attempt to peer directly inside targeted craters, said lead
scientist Sean Solomon, with Columbia University's Lamont-Doherty
Earth Observatory in New York.
It also will look for magnetized crust in an effort to flesh out the
odd story of why such a tiny planet has such a strong, and recently
discovered asymmetrical, magnetic field.
(Editing by Lisa Shumaker)
[© 2015 Thomson Reuters. All rights
reserved.]
Copyright 2015 Reuters. All rights reserved. This material may not be published,
broadcast, rewritten or redistributed.
 |
