Mercury - the sun's nearest planet - has been visited only once by a space mission. But that's about to change, and scientists like Ann Sprague of the University of Arizona's Lunar and Planetary Laboratory are excited.
Sprague, a local author and scientist specializing in Mercury's atmosphere, gave a public talk on it at UA's Flandrau Science Center during the transit of Mercury last week, Nov. 8.
The Mariner 10 Mission to Mercury in the early 1970s left more than half the planet unmapped and left scientists with a lot of unanswered questions, Sprague said.
Two major unanswered questions are why is Mercury so dense, and what makes up its apparently metal-rich core, Sprague said.
Scientists are puzzled as to why Mercury is by far the densest of the terrestrial planets, and they wonder if Mercury's core might really make up more than half the planet.
Scientists like Sprague are also interested in learning more about Mercury's geologic history, the mysterious materials at Mercury's poles, and the somewhat puzzling existence of a Mercurial magnetic field.
Thanks to NASA's MESSENGER, the first orbital mission to the sun's innermost planet, Sprague and others may soon have a chance to learn more about Mercury.
MESSENGER, which stands for MErcury Surface, Space ENvironment, GEochemistry and Ranging, was launched in August of 2004 and will make its first collection of Mercurial data during a flyby in 2008. Sprague has formally requested to be part of the group of scientists getting an exclusive first look at the returned data.
Two scientists from UA's Lunar and Planetary Laboratory are on the MESSENGER science team. William V. Boynton, who chairs the Messenger science team geochemistry group, will lead the analysis of geochemical remote sensing measurements. Robert G. Strom, who has been studying Mercury since Mariner 10 and is considered one of the founders of modern planetary geology, is a member of the geology group. Strom will lead the analysis of Mercury's geologic history and help analyze spectral measurements of Mercury's surface.
MESSENGER will make several flybys of Mercury between 2008 and 2009, when it will do most of its surface imaging. The spacecraft will attempt a close orbit of the planet beginning in 2011.
During its Mercurial orbit, MESSENGER will make use of a variety of spectrometers and magnetometers to collect information about the planet's surface, core, atmosphere, and magnetic field.
If Sprague's proposal is accepted, she'll be able to access mission data much sooner than if she had to wait for its publication, which Sprague said could take years.
In the meantime, Sprague said she hopes Mercury's transit and her discussion of the planet will increase public interest in Mercury and the MESSENGER mission. Sprague said she thinks it's important for people to take an interest in the planets of the solar system because doing so enables us to gain clues to the origins of the planets and the origins of life.
The next major event coming up for MESSENGER will be the craft's second flyby of Venus early next year, which will help the craft adjust its trajectory on the way to Mercury. MESSENGER's first Venus flyby happened late last month.