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Orbiter Mars-ward shift today

New Delhi, Nov. 30: India’s space agency will fire an engine aboard its Mars orbiter spacecraft early on Sunday to drive it out of its orbital paths around Earth and into a giant hyperbolic trajectory towards Mars.

The liquid-fuelled rocket engine will be fired for 23 minutes starting at 12.49am to increase the spacecraft’s velocity by 648 metres per second, a senior Indian Space Research Organisation (Isro) official said tonight.

The velocity addition will move the spacecraft into a trajectory that, if all goes to plan, will make it approach Mars on September 24 next year after a journey of 680 million kilometres. The engine will remain silent during the 10-month trip and the spacecraft will travel on its own momentum.

During the approach phase, Isro engineers will have to fire the onboard engine again to slow the spacecraft down and allow it to be captured by Mars’s gravity.

The spacecraft, launched on November 5, carries five scientific instruments to study the Martian atmosphere, weather and topography and look for signs of methane on the planet.

Its elliptical orbit will take the orbiter to a closest point of 365km, and most distant point of 80,000km, from the planet’s surface.

Isro’s Rs 450-crore Mars mission is India’s first to a planet explored so far only by American, Russian and European satellites.

Throughout the orbiter’s remaining journey, engineers at Isro’s control centre in Bangalore, working in eight-hour shifts 24x7, will track the spacecraft relying on a flow of data pouring in from its subsystems and reflected on their computers.

The engineers plan to use three dish antennas at Isro’s Deep Space Network in Byalalu, Karnataka, for the purpose. The antennas, with diameters of 11 metres, 18 metres and 32 metres respectively, will be used progressively as the distance to the spacecraft grows. A Deep Space Network with relatively larger antennas — 34 metres and 70 metres — run by American space agency Nasa’s Jet Propulsion Laboratory (JPL) will also help in the tracking, filling in gaps and providing backup.

“There might be occasions when we have to make minor trajectory corrections,” a senior Isro official told The Telegraph.

“In such situations, we’ll ascertain the trajectory with the help of the JPL and then make corrections.”

Minor corrections to the spacecraft’s trajectory will be typically carried out through short-lasting firings of an onboard engine that will cause subtle changes of direction.

Since its launch, the spacecraft has been in orbit around Earth but Isro engineers have in planned steps nudged it into higher orbits. The last orbit-raising operation on November 16 had placed the spacecraft into an orbit with an apogee, or most distant point from Earth, at about 192,000km.