Bangalore, Sep 22 (Agencies): In a crucial manoeuvre ahead of India's Mars orbiter's entry into the final destination on September 24, the main liquid engine on the spacecraft was today successfully test fired and its trajectory corrected.

The 440 Newton Liquid Apogee Motor (LAM) engine, idling for the last 300 days on the Mars Orbiter Mission, was fired for four seconds, raising the confidence level of ISRO about the success of insertion of the spacecraft into the Martian orbit.

"Main Liquid Engine test firing on Mars orbiter spacecraft successful: We had perfect burn for 4 seconds as programmed. The trajectory has been corrected. Mars Orbiter Mission will now go ahead with the normal plan for Mars Orbit Insertion," said ISRO.

The success came even as MOM today entered the Mars Gravitational Sphere of Influence.

"Our navigators' calculations show that MOM has entered the Gravitational Sphere of Influence of Mars," ISRO said.

The spacecraft was within 5.4 lakh km radius of the Mars' Gravitational Sphere of Influence, it said. On a 666 million km journey, the spacecraft escaped the earth gravity pull on December 1 last.

In the last lap on September 24, the orbiter has to be slowed down from 22.1 km per second to 4.4 km per second in relation to the red planet to be captured by the Martian orbit. The engine would be fired for 24 minutes on that day to reduce its velocity and insert it into the Martian orbit.

ISRO has already uploaded commands to help the spacecraft automatically enter the orbit. The mission's success will make India the first country in the world to go to Mars in the maiden attempt.As India's MOM was on course to its destination, US NASA's MAVEN spacecraft began orbiting Mars today.