ISRO successfully performs first TCM on Mars Orbiter

The spacecraft is presently travelling some 2.9 million kms away from Earth

Image via Shutterstock

The First Trajectory Correction Manoeuvre (TCM) of Mars Orbiter Mission (MOM) was completed successfully today morning. The Indian Space Research Organisation (ISRO's) MOM spacecraft started the 44 seconds long firing of its 22N thrusters, for the TCM on Wednesday early morning and Isro announced the firing was successful at around 6.45 a.m..

 

Earlier as part of the correction the MOM spacecraft has been rotated from its nominal orientation to the orientation required for the first TCM. On December 1st India joined interplanetary travelers, after successfully conducting a critical manoeuvre to place the Mars orbiter spacecraft in the Mars transfer trajectory. Country's first mission to Mars left Earth's orbit in the early hours of Sunday, clearing a critical hurdle in its journey to the red planet, which could not be succeeded by the emerging rival Chinese agency.

 

Today’s TCM is one of the crucial TCMs, since after the Trans-Mars Injection, MOM navigators spent days ranging and measuring the velocity of the spacecraft and precisely determined its flight path. Based on this, the firing duration and delta-v has been calculated which will correct the deviations before they have a chance to grow large. During the Trajectory Correction Manoeuvre, accelerometers on board MOM gives the information when the desired delta-v is achieved.

 

Mission plan to handle even the maximum Earth to Mars round-trip light time delay of 42 minutes is in place. The spacecraft is equipped with autonomy features that will safeguard the spacecraft, when micromanaging the mission from Earth is not feasible due to communication delays. MOM team is gaining hands-on experience in handling the communication delay as it keeps increasing gradually.

 

The first roll over was to achieve the right orientation necessary for carrying out the TCM. MOM will them command the 22 N thrusters on board to fire about 44 seconds and attain the necessary incremental velocity, said Isro.

 

After the firing, MOM rolled back to an optimal orientation which ensures continuous communication with Earth, uninterrupted power generation and proper solar heating. Two-way communication delay is now about 20 seconds.

 

Since MOM is about 2.9 million kms away from Earth, the amount of time required for the singla to go and come back is about 20 seconds, Hence the entire operation is managed by the onboard computer.

 

On December 9, Isro said "the beastly energy of the launch vehicle and the brute force of the Liquid engine on board MOM have set it on course to Mars. Its now the turn of the tiny thrusters, to play their part in fine tuning the trajectory for achieving the right conditions for Mars capture".

 

These 22 N thrusters on board MOM will be fired to precisely steer MOM to Mars during the four TCMs. Isro's navigation team has got a precise understanding of the present trajectory of MOM based on the range and velocity data acquired over the several days since Trans Mars injection (TCI), said Isro.

 

The next mid course correction Manoeuvre, subsequentlyone will be in April and another one in August next year.

 

These are all ensure that on September 24, 2014, when we are near the Mars, we are at 500 plus or minus 50 kms.

 

Two weeks before reaching Mars, there will be one more Manoeuvre. So there will be four correction Manoeuvres. Next crucial event is on September 24, 2014, which is the insertion of the spacecraft into Mars' orbit.