Posts Tagged ‘Trans Mars Trajectory’

Heigh-ho, ISRO, it’s off to Mars we go

November 30, 2013

UPDATE!!

Trans-Mars injection has been completed successfully.

  • Trans Mars Injection (TMI) operations completed successfully. The liquid engine burn time was 1328.89 sec and the imparted incremental velocity was 647.96 m/sec.
  • Trans Mars Injection (TMI) operation began at 00:49 hrs (IST) on Sunday Dec 01, 2013.
  • Forward rotation of spacecraft, to put it into the right orientation to perform Trans Mars Injection (TMI) operation has been completed successfully at 00:30 hrs IST on Dec 1, 2013

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A big night for ISRO and congratulations are due! And not least for ISRO’s coverage of the event – almost live – on their Facebook page. (I have not been too enamoured of the ISRO website but somebody did a great job on the live updates).

The Indian Mars Orbiter (Mangalyaansuccessfully completed its final burn in earth orbit and has been inserted into a Trans Mars Trajectory (to be confirmed). It may just be one small step in Man’s exploration of space but it is a giant leap for ISRO. After spending a month in 6-ever increasing orbits around Earth the craft now has a 300 day journey to get to Mars with the possibility of 3 mid-course corrections before the liquid engine has to be fired up again to enter into orbit around Mars.

So far, so good!

A number of “firsts” for the Indian Space Research Organisation (ISRO) and, no matter what may now happen, a great many accomplishments already in the bag. The lack of a sufficiently powerful rocket necessitated that the craft first enter earth orbit and then the month-long, laborious compared to NASA, procedures where the space craft engine had to be used  to first to increase the earth orbits and then – tonight – be fired for an extended time (23 minutes) to be inserted into a heliocentric Trans Mars Trajectory.

Mission Operations Complex ISTRAC  Bangalore.

Mission Operations Complex ISTRAC Bangalore.

Photo

One hour before the final engine firing the craft was put under the control of its on-board computer which was to carry out the final burn. Forward rotation of the spacecraft to put it into the right orientation for the burn was carried out and completed about 20 minutes before firing. Engine firing started on schedule just before the craft reached perigee. The actual burn of the 440 N Liquid Engine lasted its planned 23 minute long firing entirely under local on-board computer control. The objective was to impart an incremental velocity of 648 m/s and the indications are that that was achieved. The engine firing manoeuver seems to have gone exactly to plan. The orbit determination team have now to confirm now confirmed the trajectory actually achieved.

The new heliocentric orbit is yet to be confirmed. confirmed

The ISRO chorus (with apologies to Walt Disney)

Heigh-ho, ISRO

It’s off to Mars we go

We keep on working all day long

Heigh-ho, ISRO 

Photo: Liquid Engine propels MOM into Mars Transfer Trajectory and India into interplanetary space !Trans-Mars injection has been completed successfully.

Liquid Engine propels MOM into Mars Transfer Trajectory and India into interplanetary space !Trans-Mars injection has been completed successfully. ISRO

 

Moment of truth approaches for India’s Mars Orbiter Mission

November 28, 2013

When everything is for the first time,achievements are incremental and there are very many critical “moments of truth” to meet and overcome. But now comes a very large “moment of truth” as ISRO prepares to inject the Mars Orbiter spacecraft into its Trans Mars Trajectory.

India’s Mars Orbiter (Mangalyaan) is currently in its final orbit around the earth and is scheduled to fire its 440 Newton liquid engine at 0049 hours IST on Sunday morning ( 1919 GMT Saturday 30th November).  It entered its final Earth orbit yesterday which has an orbital period of 5575 minutes (just under 4 days) and it should be approaching apogee later tonight (early hours of Friday morning) and the next engine burn will take place at perigee. Currently apogee is about 193,000 km from earth and perigee is around 350km.

The spacecraft must first be manoeuvred into the right attitude using its thrusters for the firing of its main engine which must then be fired to impart the correct change of velocity (delta-vee). Both, an incorrect attitude and/or an incorrect delta-vee are potential sources of error. Three mid-course corrections are planned  (the first on December 11th) but the margin of error allowable is still extremely small. Too low a velocity change could leave the craft in earth orbit or put it into a heliocentric orbit which does not get close enough to Mars. Too high a delta-vee would also put the craft into a heliocentric orbit which would eventually decay into the sun. I believe there is no chance of achieving a velocity high enough to escape the sun. And even if the velocity change is correct but the direction is too far in error then just another orbital path around the sun would result.

NDTV:“The trans-Mars injection- we are planning to depart on December 1, 2013 early hours of 00:49 hours IST and we are going to burn a liquid engine for duration of roughly 23 minutes which will impart an incremental velocity of 648 metres per second consuming a fuel of 198 kgs,” ISRO Scientific Secretary V Koteswara Rao told reporters in Bangalore.

K. Radhakrishnan, ISRO Chairman. (For the) trans-Mars injection and its insertion into the Martian orbit, the firing of the liquid engine is done in a closed loop mode. Here, a precision accelerometer is used to estimate the incremental velocity added as the liquid engine burns and when the accelerometer gives a feedback that the required incremental velocity added to the spacecraft has been achieved, the burning of the liquid engine is automatically terminated. So, minor variations in the performance of the liquid engine will not matter because we are cutting off its burning based on the delta-v that is achieved. That is why we call it closed loop of firing. … The spacecraft’s propulsion system, i.e., the 440 Newton liquid engine, will complete its first phase of operations on December 1. It has to be re-started for its operation on September 24 (2014).

MOM Trans Mars Injection ISRO

MOM Trans Mars Injection ISRO

ISRO: This voyage is achieved by a combination of navigation and propulsion technologies, governed by the gravity of Sun and Mars, and assisted by the 440 N Liquid engine. Further fine tuning of the trajectory is achieved using the Attitude and Orbit Control Thrusters during the Trajectory Correction maneuvers planned en route.

… on December 11, we plan to have one small firing for mid-course correction of the spacecraft. There may be one more mid-course correction during the helio-centric phase, and subsequently, a fortnight before the spacecraft’s arrival near Mars, there will be one more mid-course correction. So there will be three mid-course corrections between December 1, 2013 and September 24, 2014. 

Mangalyaan is eventually to be placed into a Martian orbit, with a periapsis height of 365 km, apoapsis height of 80,000 km and an orbital period of about 77 hours.

So on Saturday I shall have as many of my fingers crossed as I can manage. I suspect there will be many others doing the same across India.


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