CHENNAI: Cruising towards a historic feat, the Indian space mission to Mars today crossed half the total distance to the red planet from Earth and was very much along the designated helio-centric trajectory.At exactly 09.50 am (IST), the Mars Orbiter Mission spacecraft crossed the mid-point of its path to Mars, thereby has travelled 337.5 million km in its elliptical orbit around the sun, ISRO sources said.It took four minutes and 15 seconds for a message to reach the spacecraft and return, they said.Incidentally, the spacecraft is crossing half the total distance on its way to Mars, a day after Earth was at its closest to the red planet, in their respective orbits.The mission was very much in track and it was evident with the fact that the second Trajectory Correction Manouvre (TCM) planned on the spacecraft has now been considered not necessary and is expected to be performed only in June, scientists said.ISRO has been continuously monitoring the spacecraft using its Deep Space Network complemented by that of Jet Propulsion Laboratory of the NASA and the five scientific instruments onboard the craft were "in good health."Periodic tests were also being done on the different levels of autonomy built into the spacecraft for managing contingencies."Soon, the High Gain Antenna of the spacecraft will be put in service for handling communications with the ground stations," an ISRO statement said.Of the four TCMs planned on the spacecraft, the first was performed on December 10 last year and the remaining are scheduled in June, August and September, respectively.India's maiden mission to Mars was successfully launched on board PSLV C 25 from Satish Dhawan Space Centre at Sriharikota spaceport, some 100 km from here, on November 5 last year.The Rs 450-crore mission intends to explore the presence of Methane in the Red Planet with the help of five scientific instruments on board the spacecraft.Of the total 51 missions undertaken to Mars (excluding MOM), only 21 have been successful.If all goes well and the satellite orbits around Mars, India's national space agency ISRO would be the fourth after agencies in US, Russia and Europe to have undertaken a successful mission to the red planet. Attempts by China and Japan to send missions to Mars have failed.