Article Posted on : - Mar 18, 2011

Artist's concept of MESSENGER in orbit around Mercury. A NASA photo

WASHINGTON (BNS): Achieving a historic milestone, NASA spacecraft MESSENGER Friday entered the orbit of Mercury, thereby becoming the first scientific mission to reach the innermost planet of the Solar System.

The spacecraft successfully achieved orbit around Mercury at approximately 9 pm EDT Thursday (0100 GMT Friday), NASA announced.

Executing a 15-minute maneouver, the orbiter fired its main thruster at 8:45 pm EDT, slowing the spacecraft by 1,929 miles per hour and easing it into the planned orbit about Mercury.

At 9:10 pm EDT, engineers Operations Center, received the anticipated radiometric signals confirming nominal burn shutdown and successful insertion of the MESSENGER probe into orbit around Mercury.

The spacecraft rotated back to Earth by 9:45 pm EDT, and started transmitting data, the space agency said.

Upon review of the data, the engineering and operations teams confirmed the burn executed nominally with all subsystems reporting a clean burn and no logged errors, it said.

“Achieving Mercury orbit was by far the biggest milestone since MESSENGER was launched more than six and a half years ago,” Peter Bedini, MESSENGER project manager of the Applied Physics Laboratory (APL), said.

The MErcury Surface, Space ENvironment, Geochemistry, and Ranging, or MESSENGER spacecraft, launched on August 3, 2004 to unravel the mysteries of Mercury, had conducted six interplanetary flybys during its about 7.9 billion kilometers space voyage.

It had followed a path through the inner Solar System during which it conducted one flyby of Earth, two flybys of Venus, and three flybys of Mercury.

MESSENGER’s rendezvous with Mercury on Friday took place about 155 million kilometers from Earth, NASA said.

In the coming weeks, NASA engineers will focus on ensuring that all systems of the spacecraft are working well in Mercury's harsh thermal environment.

From March 23, the instruments on board the spacecraft will be turned on and checked out, and on April 4 the mission's primary science phase will begin, the space agency said.

MESSENGER is carrying seven scientific payloads and is set to revolve around Mercury for one Earth year.