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Srinivas Laxman

Mars Orbiter Mission test firing successful; all ready for orbit insertion

Posted by Srinivas Laxman

22-09-2014 9:00 CDT

Topics: Mars Orbiter Mission (MOM), mission status

The mood became instantly festive in the Mars mission control room in Bangalore on Monday following the success of the crucial four-second test firing of the Mars Orbiter Mission’s (MOM) 440-Newton liquid apogee motor. It was a trial run for Wednesday’s orbit insertion. A few seconds after the results were known, the mission posted to its Facebook page: "Test firing successful. We had a perfect burn for four seconds as programmed. The trajectory has been corrected. MOM will now go ahead with the nominal plan for the Mars orbit insertion."

Mars Orbiter Mission fires its main engine


Mars Orbiter Mission fires its main engine

Explaining the reason for a mere four-second test burn, ISRO chairman K.Radhakrishnan, said "There was a minimum time of firing necessary and four seconds are good enough to get at least three or four good points to know that the fluid flow is proper and also to measure the acceleration imparted correctly." Radhakrishnan had told me recently that if the test went well it would enhance the confidence of the Mars team that the orbit insertion on Wednesday will go off without a hitch.

This means that Plan A could be implemented for the insertion, which  envisages firing both the liquid apogee motor as well as the eight 22-Newton attitude control thrusters. A significant aspect of the test firing was that it was the first time a trajectory correction maneuver was executed along with the trial of the liquid apogee motor.

On Monday MOM also moved into the Mars sphere of influence, which means it has come under the gravity of the Red Planet. The Mars sphere of influence reaches to about around 570,000 kilometers from the surface of the planet. The mission has been split into three phases: the geocentric phase, when MOM was under Earth's sphere of influence; the heliocentric phase when it came under the influence of the Sun; and the Mars sphere of influence, which it entered on Monday.

On September 19 MOM went into a capture configuration in preparation for the insertion.

In another development, following the successful entry of NASA's MAVEN at  Mars on Monday, NASA scientists have emphasised the need for greater collaboration and sharing of data between NASA MAVEN and ISRO MOM scientists. Jim Green, director of NASA's Planetary Science Division, said that as both MOM and MAVEN get into orbit and scientists begin to understand their data these opportunities will grow. He said that ISRO and NASA scientists have already initiated discussions on this issue. Scientists of ISRO and NASA are working on a mechanism to collaborate on setting up a joint Mars working group under the auspices of the State Department's US-India Civil Space Joint Working Group.

In fact, a recent posting in MAVEN's official Facebook states that "MOM and MAVEN share some science objectives and carry some similar instrumentation. As such there are plans to share data regarding Mars' upper atmosphere wherever it is appropriate." One of the instruments on board MOM called Mars Exospheric Neutral Composition Analyser (MENCA) will study the upper atmosphere of Mars and why it has escaped—similar to what MAVEN will be doing.


See other posts from September 2014


Or read more blog entries about: Mars Orbiter Mission (MOM), mission status


Anil: 09/22/2014 09:54 CDT

Mother of all Slingshots!!!! mom

DVSathe: 09/22/2014 10:31 CDT

The ISRO scientists / technicians have done a commendable job of firing the Apogee motor and putting the Mangalyaan in the orbit around Mars. There is a problem, however, in learning the relevant part of HSC physics and hence motivating students to take up the challenges such as MOM. Let me explain that problem for the benefit of teachers and students – both. A two-stage rocket is used in projecting a satellite around a planet. First stage takes the satellite to the required height. Then it is turned through 90 degree and given a critical (orbital) velocity by a requisite horizontal thrust, so that it can orbit around the planet. This was done by the Apogee motor in the Mangalyaan. But while find the equation of critical (orbital) velocity of satellite teachers (and books also) equate the centripetal force (F= mv^2/r) with the gravitational force (F = GMm/r^2) and get the required equation of critical (orbital) velocity, v^2 = GM/r. Hence question: The motion of satellite around the planet is due to horizontal thrust or due the gravitational force? It’s a billion Rupee question because it is a global one and confronting for 45 years.

Ray Gunn: 09/23/2014 06:00 CDT

Perhaps the U.S. will start outsourcing their planetary missions. :)

Shreerang Kaulgi: 09/24/2014 02:11 CDT

The horizontal thrust imparted by the launcher gives the spacecraft the orbital speed. Due to curvature of the orbit, a centrifugal force develops which is countered by the gravitational pull. The balance of the two keeps the spacecraft in orbit. The motion of the spacecraft is thus due to the horizontal thrust given while launching which again is dependent on the gravitation force exerted by the parent body. Due to the extreme difference in masses of the parent body and the spacecraft, the horizontal velocity of the spacecraft is predominated by the parent body. In a circular orbit, the centrifugal force and the gravitational force equate. The meaning of the billion rupee question posed is not very clear.

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