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. PSLV C 25 rocket.
2. 24 September 2014, MOM entered the Aero-centric orbit of Mars.
The control of MOM is done from the Satellite Control Center (SCC) at Peenya in Bangalore once they are in the proper orbits. The telemetry data is received and processed here by scientists. Adjustment of positions and manoeuvres of spacecrafts (including geostationary satellites also) is done from here.
SCC is part of the master control facility MCF of ISRO (Indian Space Research Organization) at HASSAN in Karnataka. Project and mission heads take decisions from here.
The Earth station to receive all the telecommunication signals is at a different geographical site, where huge antennas are built in a noise-free remote area.
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3.
See the diagram which show the first two phases. 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).
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Accommodation of payloads means making the payloads and MOM suitable to withstand all conditions that will be present in its orbit and any other possible events that may be encountered. Atmospheric conditions, dust, radiation from every where & light from Sun, temperature ranges, and possible eclipses. Strengths and characteristics of materials used should be suitable to these.
Further the capabilities of the electronic instruments and imaging apparatus are designed to be able to sense or capture the data from the atmosphere and the shallow surface of Mars.
See diagram of MOM please. The 2nd diagram shows the payloads clearly.
Payloads on Mars Orbiter Mission:
MOM has 5 scientific exploration based instruments or devices. These are the payloads (electronic devices). Lyman-Alpha Photometer (LAP), Methane sensor(MSM), Exospheric Neutral composition Analyzer (MENCA), Thermal Infrared Imaging Spectrometer(TIS), Mars Color camera (MCC). See diagram for their accommodation. These are functioning now and are sending data to us through the transponder device. These are weighing 1 kg to 3 kg each.
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 fuel to last for 1 year as against 6 months intended mission (when it entered the Aero-centric orbit). There are three antennas high gain antenna, medium gain antenna and low gain antenna. 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.
Aluminum and CFRP (Carbon Fiber Reinforced Polymer) material is used for MOM as it has high strength/unit mass, no rusting, and high temperature withstanding capability.
