Early Monday morning, NASA's Messenger spacecraft hurtled by Mercury, snapping hundreds of pictures of the planet closest to the sun.
NASA announced Monday that Messenger, armed with an array of six analysis instruments, flew 125 miles above the planet's cratered surface at 11.40 on Sunday night. This is the spacecraft's second of three passes over Mercury. It made its first flyby in January.
While Messenger was taking photos and collecting other data from the planet, it used Mercury's gravity to give it a 'critical' assist to keep the probe on course. NASA scientists hope to move the spacecraft into position to actually begin orbiting Mercury in March 2011.
NASA hopes that Messenger becomes the first spacecraft to orbit the planet, which is only 36 million miles from the sun. In comparison, the Earth is 92,900,000 miles from the sun.
Part of Messenger's mission is to help scientists figure out whether there is ice hidden on the poles of Mercury. Finding ice there would be a major discovery, since the planet is so close to the sun its surface is 11 times brighter than Earth's. NASA noted in online documents that while Mercury's surface temperatures can reach about 450 degrees Celsius, deep craters near its poles are in the shade and there the temperature can plummet to minus 210 Celsius.
Ice was one of the major discoveries that the Phoenix Mars Lander made this summer on the Martian north pole. Instruments on the lander conducted several tests on soil dug up by a robotic arm and discovered what scientists had been hoping to find - elements that could support life.
Messenger is equipped with six of its own instruments to conduct tests on the Mercury trip.
According to documents on NASA's website, the spacecraft includes a gamma ray and neutron spectrometer that is designed to map different elements and offer clues about the existence of ice at the planet's poles. A magnetometer is attached to a nearly 12-foot boom and will scan the planet for areas of magnetized rocks. And a dual imaging system has wide- and narrow-angle imagers that should be able to map the surface and give scientists a topographical view.
NASA scientists and engineers spent about 20 years developing new materials and technologies for Messenger.