Setting our sights on Mercury (part 3)

Posted by Rich Talcott
on Tuesday, January 15, 2008

NASA/JHUAPL/CIWOn January 14, NASA’s MESSENGER spacecraft flew past Mercury. MESSENGER — short for MErcury Surface, Space ENvironment, GEochemistry, and Ranging — made the first close-up observations of the innermost planet in 33 years. This flyby marked the first of three encounters with the planet, providing gravity assists necessary to place the probe in orbit around Mercury in March 2011.

January 15, 2008

It’s okay to exhale. Everyone involved with the MESSENGER flyby breathed a sigh of relief yesterday when the spacecraft sent back telemetry reporting everything was operating as it should. No one had much doubt that the spacecraft would perform as planned, but the confirming radio signals still sounded sweet.

MESSENGER started observing Mercury with its full suite of instruments Sunday morning. It skimmed within 125 miles (200 km) of the planet’s equator at 2:05 P.M. EST yesterday, and concluded its observations around noon EST today.

MESSENGER then started to download its science data. The spacecraft took nearly 1,300 images of the planet and studied its surface, interior, magnetic field, and thin atmosphere. Mission controllers expect it to take a week or so to return all the data. You can count on us to report the latest results as they come in.

This is the first close-up reconnaissance of Mercury since 1975, when the Mariner 10 spacecraft made its third and final flyby. Due to a quirk of Mariner 10’s trajectory, the craft saw the same hemisphere of the planet at each encounter. So, scientists have seen detail on only 45 percent of the planet’s surface. This leaves Mercury with the largest area of terra incognita in the solar system.

During this encounter, MESSENGER will view approximately half of the previously unexplored terrain. The spacecraft will also measure the planet’s surface composition, map its topography, analyze the magnetic field, and explore the ultrathin atmosphere.

See a larger view of the Mercury sequence here.

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