A NASA spacecraft will whiz over Mercury’s crater-scarred surface next Monday, getting a look at the third of the planet closest to the sun that has never been seen close-up before.
It is a return engagement for the car-sized MESSENGER probe, which darted past Mercury on January 14 during its ongoing mission to explore the small and rocky sun-baked world.
MESSENGER is due to fly about 124 miles above Mercury’s surface at nearly 15,000 mph .
The only previous times Mercury was visited by a spacecraft was in 1974 and 1975 when NASA’s Mariner 10 flew past it three times and mapped about 45 percent of its surface. January’s fly-by by MESSENGER covered another 20 percent of the surface, the U.S. space agency said.
Next week’s fly-by will cover about 30 percent more, on the opposite side of the planet from the one seen in January.
“That represents an area bigger than the land area of South America that will be seen for the first time by our spacecraft,” Sean Solomon of Carnegie Institution of Washington, the mission’s lead investigator, told reporters.
The probe is due to take 1,200 images during the encounter with Mercury, which is two-thirds closer to the sun than Earth.
Data from the January fly-by showed that volcanic activity played a key role in forging Mercury’s surface and that the planet has been shrinking more than expected over time.
It also revealed unique volcanic structures, new details of an enormous impact crater and evidence that Mercury’s magnetic field is generated in its molten iron core, NASA said.
MESSENGER will fly past Mercury again in September 2009 before settling into orbit around the planet in 2011.
NASA said the primary purpose of next week’s fly-by is to allow the probe to use Mercury’s gravity to ease into a better position for its yearlong orbit in three years.
But MESSENGER’s seven scientific instruments will be busy amassing all the data they can, it said.
“We expect a whole lot more great information coming out next week,” NASA scientist Marilyn Lindstrom said.
In many ways, Mercury has remained a mystery to scientists and its proximity to the sun has made it difficult to observe from Earth. Its surface is a mix of plains, craters caused by bygone impacts with space rocks, and long, winding cliffs.
MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry and Ranging, was launched in 2004.
With many scientists now considering Pluto a dwarf planet, Mercury holds the distinction as the solar system’s smallest planet, with a diameter of 3,032 miles, a third the size of Earth and only a bit larger than the Earth’s moon.