Mercury probe points to different origin for 1st planet
September 18, 2012 -- Updated 2250 GMT (0650 HKT)
High levels of magnesium and sulfur on the surface of Mercury, suggest its makeup is far different from other planets.
- NASA probe gives insight into Mercury's formation
- The surface has sulfur levels 10 times higher than Earth's
- The MESSENGER orbiter has been circling Mercury since March 2011
(CNN) -- X-ray data from NASA's MESSENGER probe points to high levels of magnesium and sulfur on the surface of the planet Mercury, suggesting its makeup is far different from that of other planets, scientists say.
The unmanned orbiter has been beaming back data from the first planet for a year and a half. Readings from its X-ray spectrometer point to a planet whose northern volcanic plains formed through upwellings of rocks more exotic than those often found on the Earth, the Moon or Mars, said Shoshana Weider, a researcher at the Carnegie Institution of Washington.
"Before this MESSENGER mission, a lot of people assumed it was very like the Moon -- it's dark, it's grey," Weider said. But while the Moon's surface formed when light materials floated to the top of an ocean of molten rock, the low level of calcium on Mercury indicates that didn't happen there.
"This gives us clues to the kind of precursor materials that accreted to form Mercury, in an extremely oxygen-poor environment," Weider said.
A short history of the Space Shuttle Endeavor
The concentration of sulfur on the surface is about 10 times that seen on Earth, she said. And while Mercury's iron core "makes up a huge amount of the planet," very little is found at the surface.
The northern region of volcanic plains differs significantly from the surrounding portion of Mercury, where the surface -- as dated by the number of craters -- is about a billion years older, Weider said.
The results were published in the latest issue of the Journal of Geophysical Research, a peer-reviewed publication of the American Geophysical Union. Weider and her co-authors studied 205 different readings from the spectrometer to produce their results.
MESSENGER -- an acronym for the Mercury Surface Space Environment, Geochemistry and Ranging mission -- has been orbiting Mercury since March 2011. It's only the second spacecraft to reach the planet and the first to circle it.
It's about 5% the size of Earth and revolves around the sun every 88 days. It rotates very slowly -- once every 58 Earth days -- and the surface temperature on the day side can reach 800 degrees Fahrenheit (425 C), according to NASA.
Read more space and science news on CNN's Light Years
Today's five most popular stories
Part of complete coverage on
February 6, 2013 -- Updated 1526 GMT (2326 HKT)
Advocates say the exam includes unnecessarily invasive and irrelevant procedures -- like a so-called "two finger" test.
February 6, 2013 -- Updated 0009 GMT (0809 HKT)
Supplies of food, clothing and fuel are running short in Damascus and people are going hungry as the civil war drags on.
February 6, 2013 -- Updated 1801 GMT (0201 HKT)
Supporters of Richard III want a reconstruction of his head to bring a human aspect to a leader portrayed as a murderous villain.
February 5, 2013 -- Updated 1548 GMT (2348 HKT)
Robert Fowler spent 130 days held hostage by the same al Qaeda group that was behind the Algeria massacre. He shares his experience.
February 6, 2013 -- Updated 0507 GMT (1307 HKT)
As "We are the World" plays, a video shows what looks like a nuclear attack on the U.S. Jim Clancy reports on a bizarre video from North Korea.
The relationship is, once again, cold enough to make Obama's much-trumpeted "reset" in Russian-U.S. relations seem thoroughly off the rails.
Ten years on, what do you think the Iraq war has changed in you, and in your country? Send us your thoughts and experiences.
February 5, 2013 -- Updated 1215 GMT (2015 HKT)
Musician Daniela Mercury has sold more than 12 million albums worldwide over a career span of nearly 30 years.
Photojournalist Alison Wright travelled the world to capture its many faces in her latest book, "Face to Face: Portraits of the Human Spirit."
February 6, 2013 -- Updated 0006 GMT (0806 HKT)
Europol claims 380 soccer matches, including top level ones, were fixed - as the scandal widens, CNN's Dan Rivers looks at how it's done.
February 6, 2013 -- Updated 1237 GMT (2037 HKT)
That galaxy far, far away is apparently bigger than first thought. The "Star Wars" franchise will get two spinoff movies, Disney announced.
July 25, 2014 -- Updated 2327 GMT (0727 HKT)
It's an essential part of any trip, an activity we all take part in. Yet almost none of us are any good at it. Souvenir buying is too often an obligatory slog.