Indian Mars Orbiter out of earth's influence

The Indian Orbiter to Mars zoomed out of the earth's sphere of influence Wednesday while cruising in the sun orbit on its 10-month long voyage to the red planet.

"The Mars Orbiter has traversed beyond the earth's sphere of influence, which extends up to 925,000 km in the interplanetary space at 1.14 a.m.," the Indian space agency said in a posting on its Facebook account.

Exiting from the earth's sphere of influence means the spacecraft is out of its gravitational pull and free to cruise in the 680-million km solar orbit to reach Mars in mid-September 2014.

"Though sun's gravity dominates the solar system owing to its massive size, only very near to planets, the planetary gravity becomes stronger than that of sun and is referred as the sphere of influence," the state-run Indian Space Research Organisation (ISRO) said.

Orbits of moon and artificial satellites around fall inside the earth's sphere of influence.

A day after escaping from earth early Sunday, the spacecraft crossed early Monday the moon's orbit, which is 385,000km away and became the farthest object of India in the interplanetary space.

Scientists at the Indian telemetry, tracking and command network (Istrac) here and the Indian Deep Space Network at Bylalu, about 40km from Bangalore, are monitoring the spacecraft's movement in the sun-synchronous orbit and checking its subsystems.

The deep space network will conduct the first of the four mid-course corrections Dec 11 to ensure the Orbiter stays on course in the sun orbit.

After 290 days, the spacecraft will enter in mid-Sept the Mars sphere of influence, which is around 573,473 km from its surface, in a hyperbolic trajectory.

When the spacecraft is closest to Mars, it will be captured into the Martian orbit through a crucial manoeuvre, which involves slowing its velocity (speed).

Transition from the earth's final orbit to solar orbit was programmed in line with sun's gravity and laws of the universe to ensure Orbiter reaches precisely on time to sling into the Martian orbit in mid-Sept.

The 1,337 kg Orbiter was launched Nov 5 from Sriharikota spaceport off the Bay of Bengal, about 80km north east of Chennai, onboard a 350-tonne rocket with five scientific instruments -- Mars Colour Camera, Methane Sensor, Thermal Infrared Imaging Spectrometer, Lyman Alpha Photometer, and Mars exospheric Netural Composition Analyser.

India became the first Asian country and fourth nation in the world to leap into the interplanetary space with its Rs.450-crore exploratory mission to Mars, about 400 million km from earth.

So far, only Russia, US and the European Space Agency (ESA) have undertaken such missions.