India's Mars Orbiter Mission launches successfully
By David Szondy
November 5, 2013
Today at 2:38 PM IST, India made its bid to join the elite rank of interplanetary space-faring nations with the successful launch of its unmanned Mars Orbiter Mission (MOM) from the First Launch Pad at the Indian Space Research Organisation’s (IRSO) Satish Dhawan Space Centre (SHAR) on the island of Sriharikota, atop a Polar Satellite Launch Vehicle (PSLV-C25).
This morning, fueling of the PSLV-C25 rocket was completed and all vehicle systems were switched on for the final countdown at 6:08 AM IST. The Mobile Service Tower was withdrawn, and at 2:24 PM IST, the Mission Director gave the “Go” for launch. At 2:38 PM, the Mars rocket lifted off without a hitch with stage, strap-on rockets, and heat shield separations going as planned.
The fourth stage ignited 33 minutes after the launch at the end of an unusual 27-minute coasting phase. Then, 43 minutes into the launch, the fourth stage shut down and the probe separated from the booster less than one minute later.
There had been concern about the weather because the launch center is prone to high winds, but mission control says that today the weather was cooperative and the launch trajectory of the booster was adjusted to take into account the wind velocity at the site.
The MOM probe is currently in Earth orbit, where it is positioning itself for Mars transfer orbit insertion. Burning a combination of monomethyl hydrazine and dinitrogen tetroxide, the main engine will fire a total of six times on on November 6, 7, 8, 9, 11 and 16 to place it an elliptical parking orbit with an apogee of 23,000 km (14,000 mi) and a perigee of 238 km (148 mi). It will remain there until November 30, when it will fire its engine again to send it on its way to Mars.
A main concern of the ISRO is to get MOM to Mars using as little fuel as possible by employing a Hohmann transfer orbit. Fans of hard science fiction will recognize this as the orbital maneuver designed to travel from one planet to another using the least amount of propellant. It’s economical, but it did require a lot of patience, as the ISRO waited for Earth and Mars to move into the right positions for launch. This only occurs once every 780 days, so the next available launch window would have been January 2016.
MOM will remain remain in Earth orbit for about 25 days, then a final firing on November 30 will send the probe onto an interplanetary trajectory. Mars orbit insertion is planned for 21 September 2014, when it will go into a highly elliptical orbit with a periapsis of 377 km (234 mi) and apoapsis of 80,000 km (50,000 mi), circling Mars once every 76.72 hours.
Once on station, the MOM probe will carry out a 6 to 10-month survey of the planet’s surface and atmosphere.
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