Article Posted on : - Mar 10, 2011

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

WASHINGTON (BNS): After over six years’ of traversing in space and six interplanetary flybys, NASA spacecraft MESSENGER is all set to enter Mercury’s orbit next week.

The spacecraft, if successfully achieves the milestone on March 17, will become the first to orbit the innermost planet of our Solar System.

MESSENGER will execute a 15-minute maneouver that will place it into Mercury’s orbit. The spacecraft, having pointed its largest thruster very close to the direction of travel, will fire the thruster for nearly 14 minutes, with other thrusters firing for an additional minute, thereby slowing the spacecraft by 862 meters per second (1,929 mph), according to NASA.

During this phase, the spacecraft will consume 31 percent of the propellant it carried during launch, thereby leaving it with only 9.5 percent of the usable propellant. But the spacecraft will still have plenty of propellant for future orbit correction maneouvers, the US space agency said.

The orbit insertion will place MESSENGER into a 12-hour orbit about Mercury with a 200 kilometer minimum altitude.

At the time of orbit insertion, the spacecraft will be 46.14 million kilometers from the Sun and 155.06 million kilometers from Earth.

“This is a milestone event for our small, but highly experienced, operations team, marking the end of six and one half years of successfully shepherding the spacecraft through six planetary flybys, five major propulsive maneouvers, and sixteen trajectory-correction maneouvers, all while simultaneously preparing for orbit injection and primary mission operations,” said MESSENGER Systems Engineer Eric Finnegan.

Meanwhile, antennas from all three Deep Space Network (DSN) ground stations have began continuous monitoring of the spacecraft, allowing the flight control engineers to observe MESSENGER on its final approach to Mercury.

The spacecraft has also begun executing the last cruise command sequence of the mission, when the command sequence containing the orbit-insertion burn will start.

MESSENGER – Mercury Surface, Space Environment, Geochemistry and Ranging spacecraft – carrying seven scientific instruments, was launched on August 3, 2004 to unravel the mysteries of the planet Mercury. The spacecraft has followed a path through the inner Solar System, including one flyby of Earth, two flybys of Venus, and three flybys of Mercury.