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Minute errors can lead to failure of Mars mission: ISRO chief

October 28, 2013 12:13 IST

With the Indian Space Research Organisation set to launch the Mars Mission on November 5, Chairman K Radhakrishnan, in an interview with Praveen Bose, talks about the complexities, the challenges and the benefits of the Rs 450-crore mission. Edited excerpts:

How has the delay of a week affected the mission?

We had given ourselves a larger window, October 28 to November 19. Generally, we don’t have any missions from October, for about three months, as the weather is not conducive for a launch. November 30 is the D-Day, when the Mars orbiter would have to leave the orbit around the Earth.
If ISRO misses this opportunity, it would have to wait another 26 months. We had given ourselves a buffer so that weather conditions were accounted for. The week-long delay proved advantageous in a way. The exposure to Van Allen radiation would be that much less, as would be the impact of that on the Mars orbiter.

What are the challenges posed by the mission?

One of the technological challenges was to realise related deep-space mission planning and communication management, at a distance of about 370 million km. The spacecraft has been provided with augmented radiation shielding, for prolonged exposure in the Van Allen belt.
What are the primary objectives of the Mars mission?

One of the main objectives of the mission is to develop technologies required for design, planning, management and operations of an interplanetary mission.

What are the technological and scientific objectives?

Technological objectives of the mission include design and realisation of a Mars orbiter, with the capability to survive and perform Earth-bound maneuvers, go through the cruise phase of about 270 days, Mars orbit insertion/capture, and an on-orbit phase around Mars. In addition, it would help perfect deep-space communication, navigation, mission planning and management. ISRO would learn to incorporate autonomous features to handle contingencies. Scientific objectives include exploration of the Mars surface, morphology, mineralogy and Martian atmosphere, through indigenous scientific instruments.

What benefits could the Mars mission have?

Some of the outcomes such as the in-built autonomy we are providing in the spacecraft could become a product or a system. It could be used in satellites to improve their efficiency. So, these trickle down to application, the chief objective of the mission, which could include forecasting cyclones. There is always relevance for a mission like this.

What were the main challenges?

All aspects of the mission were challenges, right from the time available for the mission to the technologies and improvements for propulsion, navigation, tackling the 40-minute communication delay from Mars, readying the ground segment and meeting the November 30 deadline.
Minute errors in calculation could lead to the mission failing -- right from the launch into the orbit to the orbiter reaching the Mars orbit. A small error in calculation would miss the target by tens of thousands of miles. The spacecraft’s arrival point on Mars has to be calculated to an accuracy of 60 miles, about 270 days in advance.

How does it compare with Chandrayaan-I?

Compared to Chandrayaan-I, which ISRO launched in 2008-09, the Mars mission saw new challenges. While both have the PSLV rocket and an elliptical orbit for the spacecraft, for the Mars mission, you have the ‘argument of perigee’ of about 270 degrees, which requires a longer flight and a different trajectory. It is aimed at minimising the use of fuel to transfer it from an Earth orbit to a Martian one. That is also why we need the two ship-borne terminals. There would be a long coasting between the third and fourth stages, which would see a 1,500 second delay. As we have to get ignition on real time, we have monitoring stations at Sriharikota, Port Blair and Brunei.
What infrastructure did you set up for the mission?

At the ground station, we enhanced the two-Kw power system in the 32-metre antenna in our deep space network to 20 Kw. We also introduced a new system for precise ranging of the orbiter. The orbiter has been built to withstand different temperatures and conduct many tasks. Mars is about 370 million km away and there would be a communication delay of 20 minutes with Earth, each way. Rather than send a chain of commands from here to check its health and correct a problem, these are stored in the system.

Still, we can trigger these. During the 270 days of its transit, if the spacecraft develops a problem, it has to be put into a safe mode so that ground controllers can set it right. The spacecraft propulsion system must be put into sleep during the journey, and reactivated after 270 days. We made new software to know positions during the trans-Mars injection and to estimate the influence of other planets and the Sun on the orbiter.

Could you not have waited for the GSLV before launching this mission? Did competition with China hasten it?

We accommodated whatever instruments could be accommodated in these two years. The GSLV would have been an advantage only in the initial phase; otherwise, it was not important. The PSLV-XL has proven its reliability. We are not in competition withChina. They have their own missions.

What was the support from NASA?

The spacecraft has to be tracked continuously and it has to be visible at all times. While we use our own ground station at Byalalu near Bangalore, for some phases of the mission, until the spacecraft is put into the Martian orbit, we would take the support of Nasa’s jet propulsion lab’s deep space network and its three international ground stations.

What after Mars?

For now, the plan is the moon, Mars and the sun. Scientists are looking at the universe. For the next mission, we should look at larger scientific objectives, with more partners. But that depends on the progress of this mission. Then, there is the all-Indian Chandrayaan-II, with a lander and a rover, as well as the launch of the GSLV.

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