Bangalore, Sep 16 (IANS) The Indian space agency has a contingency plan to insert its spacecraft into Martian orbit Sep 24 in case its main engine fails to re-start and fire, a senior official said on Monday.

"In case the main liquid engine of 440 Newton (power) fails to re-start and fire to put the spacecraft (orbiter) into the intended Mars orbit, we will use the small eight thrusters of 22 Newton each located beneath the engine for orientation to salvage the mission," Indian Space Research Organisation's (ISRO) scientific secretary V. Koteswara Rao told reporters here.

The 475 kg spacecraft, with five scientific experiments on board, will enter the Mars sphere of influence Sep 22 after a 300-day voyage from the earth.

The liquid apogee engine (LAM) was switched off Dec 4, 2013 after the spacecraft left the earth's sphere of influence and entered into the helios-centric (sun's) orbit to cruise 666 million km towards Mars during the past nine months.

The Rs.450-crore ($70 million) ambitious Mars Orbiter Mission (MOM) was launched November 5, 2013, on board a polar rocket from spaceport Sriharikota off Bay of Bengal, about 80 km northeast of Chennai, and inserted into the trans-Martian orbit (solar orbit) Dec 1.

The space agency uses the LAM engines to insert its communication and other utility satellites in the geosynchronous orbits.

"If we miss the opportunity to insert the spacecraft into the Mars orbit using the LAM engine in 24 minutes, we will use the eight thrusters to carry out the contingency in a longer duration though the spacecraft may not get into the intended orbit," Rao noted.

Of the 51 missions to Mars by the American, Russian and European space agencies over the decades, at least nine of them failed to insert their spacecraft into the Martian orbit.