1. What was the launch vehicle used by MOM?
2. Which instrument is used for communicating with MOM?
3. When did it start orbiting Mars? By whom is it being monitored currently?
4. Write briefly about the three phases of MOM.
5. What are the payloads on MOM and how are they accommodated? IIlustrate your answer.
Answers
1. Launch vehicle used by ISRO to put MOM in to Helio centric orbit was the PSLV (Polar Satellite Launch Vehicle) XL - C25 rocket.
2. The Electronic Telecommunication Instrument onboard on MOM to communicate with it from the ground station is called the Transponder. The signals are received from air/vacuum by the antenna arrays and reflector. The collected signal is amplified by a TWT amplifier circuit and then the transponder decodes messages and processes.
3. MOM spacecraft was placed in the Aero-Centric orbit around Mars on the 24th of September. MOM is being monitored by the Spacecraft control center (SCC) of ISRO. SCC is part of Master control facility of ISRO at HASSAN. SCC is located in Peenya in Bangalore.
4.
See the diagrams for the three phases of 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.
5. Payloads on MOM are the following.
MOM has 5 instruments:
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.
