Right around noon today, if all goes as planned, a spacecraft called Messenger will swoop past the planet Mercury and begin two days of unprecedented picture-taking and data-collecting.
The flyby, the first visit to Mercury in more than 33 years by an emissary from Earth, will mark a key moment in a NASA mission that will ultimately place the first satellite into orbit around the tiny planet that sits closest to the sun.
The planetary science community is eagerly awaiting images and information that should shed light on some of the enduring mysteries about the planet -- such as where in the solar system it was formed and why its hard metal core is so large and its outer rock crust so scant, compared with those of Earth and the other rocky planets.
"Mercury is a difficult place to get to, and it's taken a long time to get back," said principal investigator Sean Solomon, who has worked on the mission for more than 11 years. "But now we're in place to learn things about one of our few sister rocky planets, and we're ready for some real surprises."
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