Bangalore:
As India's Mars Orbiter Mission raced for its tryst with the red planet on September 24, Indian space scientists are gearing up for the critical manoeuvre of the spacecraft, sounding confident about the mission's success.
The spacecraft has covered 98 per cent of its 300-day odyssey and the critical manoeuvre would be performed when the scientists restart the onboard liquid engine which is in sleep mode for nearly 10 months.
The MOM, India's first interplanetary mission, was launched on November 5, 2013 by India's workhorse Polar Satellite Launch Vehicle(PSLV) from the spaceport of Sriharikota in Andhra Pradesh.
At a media briefing, ISRO said today it was confident about the MOM's success going by its performance so far.
Commands for inserting the Mars spacecraft into the Red Planet's orbit were being uploaded since yesterday and were expected to be completed today, it said.
"The remaining crucial thing is Mars Orbit Insertion, and if you see some missions have failed because of failures in estimates in the distance from the mars, and if you see the history they were at very early stages....," ISRO Scientific Secretary V Koteswara Rao said.
"We are very confident; there is no reason, not to be confident going by the performance of the system so far. We have covered 98 per cent of the journey and another 2 per cent we are going to complete soon. We are very confident, teams are all very confident," he said.
If the Rs 450 crore MOM mission turns out to be a success, ISRO would be the fourth space agency in the world to have sent a mission to Mars.
European Space Agency (ESA) of European consortium, National Aeronautics and Space Administration (NASA) of the US and Roscosmos of Russia are the only three agencies which have so far sent their missions to the red planet.
Only 21 of the total of 51 missions sent to Mars by various countries have been successful
In the final critical manoeuvre, the space scientists would use the commands to fire the spacecraft's propulsion system for 24 minutes to slow it down just enough to be captured into the Martian orbit.
The now shut off Liquid Apogee Motor (LAM) engine has to be fired again for MOI, Rao said. The engine stored in the orbit for about 300 days without operation has to be restarted which "is very essential for MOI."
MOI will be performed on September 24 at around 7:30 AM, Mr Rao said. "When we go there, the distance between earth to the spacecraft will be 224 million km. Today, the distance between earth and Mars orbital spacecraft is 215 million km. The present one way communication is approximately 12 minutes."
He said out of the 666 million km, the spacecraft had covered 653 million km so far. "We are yet to go another 13 million km which tells us that 98 per cent of the journey has been covered so far."
"The distance between Mars and MOM is 2.496 million km approximately now; all the subsystems of the space craft are in good health and payloads health is also normal," he added.
Rao said "If you see the history of the failed missions- they have failed at various stages, some have failed during the launch which we have crossed, some of them have failed during trans Mars injection which we have crossed, some of them were lost on the way- we have completed 98 per cent of the journey."
"The remaining crucial thing is Mars Orbit Insertion, and if you see some mission have failed because of failures in estimates in the distance from the Mars, and if you see the history they were at very early stages....," he added.
India would be the first Asian country to go to Mars and also the first to succeed in the maiden attempt if the mission is successful, Mr Rao said.
On pre-injection steps, Mr Rao said the commands were being uploaded and the spacecraft has a lot of autonomy, including restoring, storing and executing command at the time when called for. "So it gives us flexibility to upload commands much earlier and download from onboard whatever data and verify them."
On September 22, the spacecraft would enter the sphere of influence of Mars.
Mr Rao said the fourth trajectory correction manoeuvre will be carried out on September 22 and this opportunity will be used to test fire the LAM engine which is going to be fired on September 24 for a longer duration.
On MOI, he said the main operation for it is on Mars orbiter spacecraft. "We have three types of antenna; one is low gain antenna, second is medium gain antenna and third is high gain antenna and....we will be changing over to medium gain antenna because it has got little larger coverage than high gain antenna."
He said 20 minutes before that, the spacecraft would have to be rotated in a direction where it is ready to be fired by reducing a velocity in order to be inserted into the Martian orbit.
Mr Rao said at 7:17 (minutes):32 (seconds) the liquid is initiated along with other eight thrusters and after 4 minutes approximately the spacecraft goes on to the other side of the mars so the radio communication from the spacecraft to Earth is blocked.
"This means after the burning we get 4 minutes of data and that too with 12.5 minutes delay on the ground and after that the data seizes to be communicated to the ground."
"Because it is starting at 7.17 with a 12 minute delay,we will know on ground at 7:30 through telemetry data how it has performed for 4 minutes duration, beyond that we will not get data on ground," he added.