India’s Mars orbiter is all set to bid farewell to Earth and begin its long journey to the Red Planet in the early hours of Sunday.
Senior scientists of the Indian Space Research Organisation (ISRO) have been gearing up over the last few days for the second-most decisive activity to set it on course to Mars.
A success will take them a step closer to a record first sure shot at Mars by any nation — but that test would only be in September 2014.
On Sunday at 12.49 a.m., when the 1,300-kg spacecraft will pass 268 km overhead, they must deflect it away from Earth and thrust it out tangentially on the planned path to Mars. They have about 22.43 minutes to do so, by firing at the engine on the spacecraft. The firing or ‘engine burn’ will raise the speed of the spacecraft and give it the power to escape beyond Earth.
Their jargon for the operation is trans-Mars insertion (TMI).
The ISRO Telemetry, Tracking & Command Network (ISTRAC) in Bangalore, where the TMI will be monitored in the minutest detail, has been a beehive of activity this past week.
The activity will start peaking from Saturday morning. The various unit heads monitoring the different systems — spacecraft, propulsion, telemetry, sensors, navigation and inertial systems among others — will take position an hour before the TMI, according to some of its officials.
On Friday around 5 p.m., directors and heads of various operations huddled together at the ISTRAC to take stock of all aspects of the Mars Orbiter Mission: they ticked the health of the spacecraft, went over the engine burn strategy and checked out emergency measures.
Ahead of the review meeting, ISRO Chairman K. Radhakrishnan told The Hindu, “Tomorrow we upload the commands of sequence in a time-tagged manner based on various parameters. Several people have been monitoring their respective sub-systems related to the spacecraft and the TMI so that the operation takes place at the appointed time without a hitch.”
He said any slightest deviation in time, duration of firing or the speed to be given to the spacecraft would be immediately red-flagged so that the controllers could set the contingencies in motion.
The engine burn to push the satellite out will start when it is over HBK (Hartebeesthoek) 60 km north of Johannesburg in South Africa, and end somewhere over Bangalore.
The burn will be the longest since the orbiter was launched on November 5. As it circled Earth several times, its orbit and speed were raised in six stages until it reached the present maximum point of 1.92 lakh km from Earth.
“We are hopeful and confident of doing it,” said Mars mission Project Director S. Arunan. The engine burn was aimed at giving the satellite a final escape velocity (which should be a minimum of 10.7 km per second). At launch, it got the speed of 9.8 km per second. The six orbit raises added 0.873 km per second; the December 1 burn should give it the last push of 0.648 km a second — which all add up to the crucial velocity of about 11.4 km per second.
M. Annadurai, Programme Director for the mission and veteran of the 2008 Chandrayaan-1 mission, earlier said the redundancies had been checked and the TMI was expected to be similar to the earlier burns. The concern was to ensure that there was not even a difference of 1 cm per second.
According to Mission Director V. Kesava Raju, the most critical aspect of the Sunday TMI was the performance of the propulsion systems.
