NASA's Messenger to observe Mercury closely

NASA's Messenger spacecraft, sent to study the Mercury 10 years back, will observe the planet at lower altitudes.

This is likely to result in exciting scientific discoveries, NASA said in a statement as Messenger completed 10 years Sunday. Mercury is the planet closest to the Sun.

The aim of the spacecraft blasted off Aug 3, 2004 from Cape Canaveral, Florida, was to take the small satellite dangerously close to Mercury's surface - paving the way for an ambitious study of the planet.

The spacecraft has so far travelled 7.9 billion km including 15 trips around the Sun and flybys of Earth once, Venus twice, and Mercury thrice before it was inserted into orbit

around its target planet in 2011, the statement added.

"We have operated successfully in orbit for more than three Earth years and more than 14 Mercury years as we celebrate this amazing 10th anniversary milestone," said Andy Calloway, Messenger Mission Operations manager from Johns Hopkins University Applied Physics Laboratory (APL).

After Mariner 10, Messenger is only the second spacecraft sent to Mercury.

Mariner flew past Mercury three times between 1974 and 1975 and collected data on less than half the surface.

Messenger took advantage of an ingenious trajectory design, lightweight materials and miniaturization of electronics - all developed in three decades since Mariner 10 flew past Mercury.

The mission has rewritten scientists' understanding of the planet "and given us plenty of surprises", NASA added.