Bharat Rakshak

Amber G. wrote:

NRao wrote:B TW, I had seen a graphic (since I was viewing it on my iPod I was unable to post it here and have since lost the URL), which showed that if the MOM was not captured by Mars, then MOM would return to the very position where it left earth.

Yes, it will return to the same (almost) position where it last got the boost from the rocket (Dec 1 ?).. ( assuming there is no further rocket burn (mid course correction - or retro-firing near Mars) and it is not disturbed by other planets ..there will be small perturbation due to Jupiter, Mars (when the probe is close - you may get bigger effect), Earth and Venus but the perturbation will indeed be small)

prasannasimha wrote:One way to look at it(the oberth effect) is a Gilli Dandu(Gilli Danda tick) where you hit the gilli first allow it to go up and at its "perigee" when its kinetic energy is maximum a simple flick will send the gilli flying .If you hit it at the apex of the gilli's flight when potential energy is maximum and kinetic energy is zer(aka apogee) you need to have a higher force .

“We are hopeful and confident of doing it,” said Mars mission Project Director S. Arunan. The engine burn was aimed at giving the satellite a final escape velocity (which should be a minimum of 10.7 km per second). At launch, it got the speed of 9.8 km per second. The six orbit raises added 0.873 km per second; the December 1 burn should give it the last push of 0.648 km a second — which all add up to the crucial velocity of about 11.4 km per second.

M. Annadurai, Programme Director for the mission and veteran of the 2008 Chandrayaan-1 mission, earlier said the redundancies had been checked and the TMI was expected to be similar to the earlier burns. The concern was to ensure that there was not even a difference of 1 cm per second.

HYDERABAD: The count down has begun. Tonight is the night Isro's scientists are eagerly waiting for. Not with their fingers crossed but with the confidence that they can get on the feeling that they have done their job right. It's not going to be a nail-biting time but an hour and time that they are looking for to.

India's Mars Orbiter Mission (MOM) will leave earth's gravity at 12.49 am tonight (past midnight on Novevmber 30). This would make it 00.49 hrs on Sunday morning (December 1).

"Everything is ready. The team of scientists is on the job," an Isro spokesperson said explaining the different stages that are to take place operationally.

With 'MOM' fans looking forward to the time when the spacecraft will leave the earth's gravity tonight, they are flooding Isro scientists with questions.

"While the Mars Orbiter Mission leaves the cradle of Earth, we need to rely on Sun's gravity and laws of the universe to deliver it to Mars at the right epoch," Isro scientists explained.

'Attitude and Orbit Control thrusters' and the liquid engine on board will be used for keeping the MOM on course. This is Isro's first ever experience of hurling a spacecraft beyond Earth's sphere of influence.

"This trans-Mars injection will herald a new era of interplanetary missions for India," Isro said.
Isro had explained that the two doughnut shaped blankets that shroud the Earth with highly charged plasma particles comprising of electrons, protons and nuclei are called Van Allen Radiation belts and that MOM has successfully sustained several passes of these lethal radiation belts speculated to have been formed by furious solar winds and harmful cosmic rays. Scientists had explained that these belts are a part of Earth's inner magnetosphere and stretch from an altitude of 1000 km to 60,000 km above Earth. They had also said prolonged exposure to these belts poses a significant threat to various sensitive components of a spacecraft. ISRO's Mars Orbiter Mission spacecraft is designed with sufficient safeguards against such fatal particles.

The question now is: Does Mars also has similar radiation belt(s)? Responding to the query by Arun K Desai, Isro replied that scientists think that Mars had a global magnetic field like that of Earth, which disappeared billions of years ago. Without the protection of this magnetic field, most of the water and atmosphere escaped from Mars. In the absence of Magnetic field, radiation belts also won't sustain.

To another question by Madhuri J Madhuri, scientists said MOM has to survive the radiation belt while moving at the natural velocity of the orbit. MOM fires its liquid engine only for making orbit changes.

It has also been clarified to MOM fans that the spacecraft does not take a longer time to reach Mars because of the extra burn as a result of the fifth orbit raising manoeuvre .

prashanth wrote:Mars orbiter poised for final toss off Earth on Sunday-The Hindu

On Sunday at 12.49 a.m., when the 1,300-kg spacecraft will pass 268 km overhead, they must deflect it away from Earth and thrust it out tangentially on the planned path to Mars. They have about 22.43 minutes to do so, by firing at the engine on the spacecraft. The firing or ‘engine burn’ will raise the speed of the spacecraft and give it the power to escape beyond Earth........ The engine burn to push the satellite out will start when it is over HBK (Hartebeesthoek) 60 km north of Johannesburg in South Africa, and end somewhere over Bangalore.

“We are hopeful and confident of doing it,” said Mars mission Project Director S. Arunan. The engine burn was aimed at giving the satellite a final escape velocity (which should be a minimum of 10.7 km per second). At launch, it got the speed of 9.8 km per second. The six orbit raises added 0.873 km per second; the December 1 burn should give it the last push of 0.648 km a second — which all add up to the crucial velocity of about 11.4 km per second.

M. Annadurai, Programme Director for the mission and veteran of the 2008 Chandrayaan-1 mission, earlier said the redundancies had been checked and the TMI was expected to be similar to the earlier burns. The concern was to ensure that there was not even a difference of 1 cm per second.

#Mangalyaan’s Navigation Challenge
“If you go outside (in
Bangalore) and hit a golf
ball towards Los Angeles,
the golf ball has to come
straight into the cup,
exactly to the hole, that’s how accurate you have to
come in. And to make it a
little bit more challenging;
the hole is moving.” –Dr. Charles Elachi, Director,
Jet Propulsion Laboratory,
NASA Mars is moving and so is the
Earth !
After 680 million kilometers
of travel, the target is to
arrive within a tiny circle of
less than two kilometers, at the right epoch.