Saving fuel critical for Mars mission success, says programme director

For M Annadurai, putting the Mars Orbiteor into space is not the end of project, but is a mere conclusion of a phase.

Little wonder then that the programme director for the mission and his colleagues spend sleepless nights, taking turns to monitor one mission or the other from the ISRO Peenya Centre, the Isro Telemetry, Tracking and Command Network (ISTRAC).

“You have called me just as I have come back from ISTRAC. I will have to get back in sometime after rest. Mission monitoring happens through the night and last night we have been rehearsing the orbit raising. We will be up the coming nights too. ISTRAC has to work 24/7, else you may not even be able to withdraw money from the ATM,” Annadurai told Deccan Herald.

Indeed, rehearsals for the most important activity, the first orbit raising scheduled for Thursday morning at 1.15 am, would continue throughout Wednesday night.

Five other orbit raisings on are scheduled before the final seventh one on December 1 at 12.42 am, when the spacecraft will be fired to get on to the Mars trajectory.

‘Crucial firing’

Annadurai said the December 1 firing is the most critical for ISTRAC. “All the nuances we learn from the previous six firings, we have to bring to the seventh.

The seventh is most crucial because we can’t afford to miss the orbit trajectory, otherwise it would upset the mission. That is why scientists have been rehearsing orbit manoeuvres continuously,” he explained. 

The Mars Mission programme director however does not underestimate the criticality of the other orbit raisings and the final orbit insertion when the probe approaches Mars in September 2014.

“We cannot afford to waste a single gram of fuel,” he said. “Every gram and kilogram of fuel saved would bolster the mission journey. That’s why rehearsals for precise orbit raising are crucial.”

An error in putting the spacecraft in the right orbit would prove costly for the mission, since each course correction would only compound the fuel wastage, Annadurai said.

“We have to spend minimal fuel because the spacecraft has to last the journey to Mars and be in the Mars orbit for six months.

The spacecraft has 850 kg of fuel and we expect to complete the mission with 800 kg of fuel. We want the remaining 50 kg to serve as reserve for an instrumental or spacecraft orientation or tilts while it is in the Mars orbit,” he said.

Each orbit raising would consume fuel, he said, pointing out that the first raising would take about 60 kg of fuel, then 80 kg, 100 kg, 40 kg etc, depending on the orbit levels in which the spacecraft flies.

“The mission has to succeed this time because in 2016 or 2018, the fuel or propellant required would be higher than the present 850 kg, which increases mission cost and complexity,” the senior Isro official said.

The spacecraft will travel at 11 km per second around the time it is to be assigned to the Mars trajectory on December 1. Thereafter it will travel between 3-4 km per second to 30 km per second depending on journey atmospherics.

NASA has already stepped in to the Mars Mission, Annadurai told this newspaper. “Every time the spacecraft goes to a higher orbit and farther side of the earth, NASA is tracking and communicating with the spacecraft.”