 "Dr K Radhakrishnan")
Are you not tensed?
If you get tensed, you intend to make mistakes plus so far things are going fine.
How is MOM (Mars Orbiter Mission) progressing?
Things are going fine. Health of the spacecraft is normal and five scientific instruments are also energised a few times during the journey.
We are getting ready for the final Mars Orbiter Insertion (MOI).
As on Wednesday, Mangalyaan has travelled 643 million kms, along with arc, and it was at a distance (radio distance) of 210.74 million kms from the Earth. The distance from the spacecraft to the Mars was 3.85 million kms. Signal delay (for one way) is 703 seconds. So about 96% of the travel is completed.
Can you take us through the chain of events scheduled from now to September 24? Also what is going to be the crucial challenge?
On September 14th, we will be uploading the sequence of commands in the spacecraft with time tagging. It will be followed by test firing and then on the crucial day (September 24) at 8.15 a.m we will be able to say the Mission is successful.
The crucial challenge will be restarting the 440N main liquid engine, the single main engine which has been sitting idle for 300 days, since the Trans-Martian Insertion Burn was performed. This is the longest interval between LAM firings ever - the engine is usually employed on Geostationary Satellites that use it over a period of days or weeks to achieve their planned orbit.
On the ground we did testing of a similar liquid engine to see its restart characteristic, this was done well before the MOM launch. It was positive. In the recent days also again we have done ground testing and it was also successful.
Do you have plan B, if there is a problem in restarting the engine?
Yes. Using the small eight 22 N thrusters for attitude control or orientation, which will not give you this original target though. It will be salvaging of the mission. But what we have tried to ensure before hand is to build in the necessary facilities for ensuring restart and also confirmation.
At the time of MOI if you find it didn't restart, then we will loose that opportunity to operate the contingency, since it has to start early considering they are small thrusters and it takes longer duration.
In Plan A it is 440N plus, with the eight thrusters, to be fired in the given duration. But if the main engine does not fire, then we have to do the entire job by the small thrusters but then you have to fire them for longer duration and if you have to get the correct ellipse around Mars, you have to start firing early. There must also be enough fuel for that purpose.
How significant is this event? Any other missions (globally) have failed at this stage?
If you look at all the history of Missions to Mars, there were several reasons why the missions failed. We have advantage of a late starter. So far we have overcome all those stages.
Next crucial phase is the MOI, there too, if you look at the 51 missions, atleast 8 or 9 Missions had problem in this insertion stage.
What are the key learnings from MOM?
One big learning is our ability to calculate and the Trans Mars Injection (TMI) and to propagate and see what could be the arrival point, which has been quite successful.
Our ability to understand the influence of the Sun and other planets on the spacecraft as it travels through the heliocentric arc and upgradation of deep space stations.
At Chandrayaan times we had spacecrafts with four lakh kms, but here we are looking at spacecraft which would have reached 227 million kms (on September 24). We have upgraded our deep space stations for MOM and now we are clear and confident about its performance.
In the spacecraft we have built several levels of autonomous. Most of these provisions have been exercised and they are working. These will be useful if we adopt them for future communication and remote sensing satellites. We have passed several ground based decision makings to decision making by the satellite on Board. If you have to take up a future good scientific Mission then certainly this is the direct learning for that.
This mission is essentially a technology mission. It is to demonstrate our ability to orbit a spacecraft around Mars and the five scientific instruments we have put in are secondary ones.
