4. Write briefly about the three phases of MARS ORBITER MISSION
Answers
See the diagram which show the first two phases of MOM. The other diagram shows MOM.
1st phase:
MOM was launched from Surface of Earth on 5th November 2013, in the first phase called Geo-centric phase. The launch was done from Satish Dhawan Space center at Sri Hari Kota in Andhra Pradesh. It was in this phase for 25 days. PSLV XL-C25 rocket carried MOM into space at the launch. In this duration MOM travelled 192,800 km from Earth’s centre. There some technical problems in putting MOM in 2nd phase and making MOM escape from Earth’s gravitational field. The escape velocity was not reached properly in expected manoeuvres.
PSLV does not have capability to launch MOM directly into the trans-mars orbit. So Apogee of MOM around Earth raised a lot and then induced in to trans-Mars orbit. During this phase the control of the space craft control center at ISRO, Peenya, Bangalore.
2nd phase:
MOM was introduced into a trans-Mars orbit on 30th November 2013, in the second phase called Helio-Centric Phase. It took a 23-minute long engine firing to escape from Earth. In this phase MOM travelled 780 million kilometres around Sun to reach the intended orbit around Mars. During 10 month travel of MOM, some manoeuvres (test firing) are done to correct its orbit and path. During this phase the communication was shifted from low gain antenna to a medium gain antenna, as the distance increased.
3rd phase:
MOM started orbiting in the specified orbit around Mars on 24th September 2014. That is the 3rd phase of MOM called Areo-Centric phase. Now MOM is sending signals corresponding to images of Mars and its atmosphere. In this orbit, MOM goes in an elliptical orbit around Mars with a periapsis of 421 km (nearest distance from Mars) and with an apoapsis of 77, 000 km (farthest distance from Mars).
MOM has fuel to last for 1 year as against 6 months intended mission. In the high gain antenna is used. There is a reflector that receives signals and transmits signals towards Earth. A transponder communicates with master control facility of ISRO, via a TWT amplifier and an antenna array.
MOM weighs 1350 kg along with its fuel. It has solar panels to generate 800 Watts of energy and is stored in a Lithium ion battery. MOM has 5 instruments (Payloads): Lyman-Alpha Photometer (LAP) , Methane sensor, Exospheric Neutral composition Analyzer, Thermal Infrared Imaging Spectrometer, Mars Color camera. These are functioning now and sending data to us.
