Scientists at the Indian Space Research Organisation (Isro) in Bangalore are preparing for a series of actions as the Mars Orbiter Mission (MOM) will reach a crucial stage on September 24. According to a top Isro official, it will be known on this day whether the mission was successful.

K Radhakrishnan, chairman, Isro, looked calm and confident. "If we get nervous or tense, we tend to make mistake. Besides, we are confident that this mission will succeed. If there is any contingency, then we have a Plan B."

The real challenge is to restart the engine, which is in idle state for around 300 days, says Radhakrishnan. After performing Trans-Martian Insertion Burn on November 30, 2013, the engine has been kept idle. This is the longest interval for an engine, which is usually employed on geostationary satellites. According to Radhakrishnan, in Chandrayaan-I, the engine was remained idle only for two weeks.

The Isro chief said of the 51 missions to Mars globally so far, eight or nine had faced issues at the insertion stage.

"We also have a Plan-B, which is using the small eight 22 N thrusters for attitude control or orientation, which will not give you this original target. It will be salvaging of the mission," he said.

If the engine will not be able to achieve its target during this test, scientists will have enough time to plan and use the eight smaller thrusters to inject 'Mangalyaan' into the Mars orbit, which, however, might not be the intended 372 km x 80,000 km orbit.

Reaching the orbit has been one of the biggest technological challenges for advanced space powers, and India would become the first country to achieve this in the first attempt and also the first Asian country to attain technological capability if it succeeds on September 24.

Interestingly, the cost this mission is around $70 million (about Rs 426 crore), which is not even one-third of other missions and even less than the production cost of the movie, Gravity, which was around $100 million (about Rs 608 crore).

Events to follow

September 24: At 6.57 am, Final phase of operation will start. Reorientation of the spacecraft should commence and it has to stabilise.

At 7.15 am: Liquid engine firing would start and in the nominal operation that should be for about 24 seconds. Then once the desired velocity is achieved, the computer will give the command to cut the firing based on the accelerometer, which is onboard the spacecraft.

Signal will take 12.5 minutes to reach here. That means Isro will know only after 12.5 minutes what is happening at the space.

At 8.15 am, Isro could confirm whether the operation is successful.

Later on the day: Colour camera will also be operated on the same date.