It will be a month to date from Sunday for the Indian Mars spacecraft’s make-or-mar manoeuvre.
On September 24, the first Indian spacecraft racing towards Mars will have reached close to it. On that day, its commanders stationed several hundred million kilometres away in Bangalore will swing it into an orbit that should hook it around the Red Planet — for a closer look as it orbits it for at least six months.
Indian Space Research Organisation says the Big Turn, called Mars Orbit Insertion (MOI), will decide whether the Rs. 450-crore Mars Orbiter Mission is a success or a flop. For the nation, it will add another feather in the cap of the space programme.
Engineers and scientists of at least three ISRO centres will soon start getting into the MOI mode, said ISRO spokesman Deviprasad Karnik.
MOI, which is planned when the spacecraft is close to Mars, involves re-orienting the spacecraft and firing the main engine, called the LAM or ‘liquid apogee motor’ on it to reduce its velocity from about 22 km a second to about 1.5 km a second. This is to ensure that the spacecraft gets captured by the Martian gravity and into an orbit that will take it around that planet.
At the time of MOI, the spacecraft will be behind Mars and out of radio range from Earth. As such, all commands will be loaded three days ahead.
Challenge
Mr. Karnik told The Hindu , “The [MOI] challenge is that the LAM has to be fired and it has been silent for over 300 days. It has to be brought alive from its long sleep. The last time we operated it was during the Trans-Mars Injection on December 1 [last year] to send the spacecraft out of Earth’s sphere of influence and into space.”
ISRO’s latest Facebook posts on the Mars Orbiter Mission said the spacecraft had travelled over 600 million km around the Sun and was just nine million kilometres away from its destination. From the Earth, it was 189 million km distant.
Before MOI, the control team at ISRO Telemetry, Tracking & Command Network must decide whether a planned minor course correction, called trajectory correction manoeuvre (TCM) is needed on September 14. Only two of four planned TCMs have been warranted since the spacecraft left Earth; they used small thrusters.
