ISRO'S Mars Orbiter Mission Completes 1000 Days in Orbit

ISRO'S Mars Orbiter Mission Completes 1000 Days in Orbit
India's indigenous Mars Orbiter Mission (MOM), the maiden interplanetary launch of ISRO, which was launched on November 5, 2013, completes 1000 earth days in its orbit.

MOM is credited with many laurels like cost-effectiveness, a short period of realisation, economical mass-budget, miniaturisation of five heterogeneous science payloads etc. Satellite is in good health and continues to work as expected. Scientific analysis of the data received from the Mars Orbiter spacecraft is in progress.

ISRO has also launched MOM Announcement of Opportunity (AO) programmes for researchers in the country to use MOM data for R&D. The success of Mars Orbiter Mission has motivated India’s student and research community in a big way. Thirty-two proposals were supported under this AO. A Planetary data analysis workshop was also conducted to strengthen the MOM-AO scientist's research interest.

First-year data from MOM was released to the public on September 24, 2016. The Mars Colour Camera, one of the scientific payloads onboard MOM, has produced more than 715 images so far. Mars Atlas was prepared and made available on ISRO website.

MOM went through a communication 'blackout' as a result of solar conjunction from June 2, 2015, to July 2, 2015. Telemetry data was received during most of the conjunction period except for 9 days from June 10-18, during superior conjunction. MOM was commanded with autonomy features starting from May 18, 2015, which enabled it to survive the communication 'blackout' period without any ground commands or intervention.

The spacecraft emerged out of 'blackout' period with auto control of the spacecraft systems successfully. This experience had enabled the mission team to program a spacecraft about one month in advance for all operations.

MOM spacecraft experienced the ‘whiteout’ geometry during May 18 to May 30, 2016. A ‘whiteout’ occurs when the Earth is between the Sun and Mars and too much solar radiation may make it impossible to communicate with the Earth.

The maximum duration of ‘whiteout’ is around 14 days. MOM spacecraft experienced the ‘whiteout’ during May 2016. However, MOM is built with full autonomy to take care of itself for long periods without any ground intervention. The entire planning and commanding for the ‘whiteout’ was completed 10 days before the actual event. No commanding was carried out on the satellite in the ‘whiteout’ period.

Payload operations were suspended.  Fault Detection, Isolation and Recovery were kept enabled, so as to take care of any contingency on the spacecraft. Master Recovery Sequencer was programmed, to acquire the attitude of the spacecraft and ensure communication with earth even in the case of loss of attitude. The spacecraft came out of ‘whiteout’ geometry successfully on May 30, 2016, and has been normalised for regular operations.

An orbital manoeuvre was performed on MOM spacecraft to avoid the impending long eclipse duration for the satellite. The duration of the eclipse would have been as long as 8 hours. As the satellite battery is designed to handle eclipse duration of only about 1 Hour 40 minutes, a longer eclipse would have drained the battery beyond the safe limit. 

The manoeuvres performed on January 17, 2017, brought down the eclipse duration to zero during this long eclipse period. On the Evening of January 17, all the eight numbers of 22N thrusters were fired for a  duration of 431 seconds, achieving a velocity difference of 97.5 m/s. This has resulted in a new orbit for the MOM spacecraft, which completely avoided eclipse up to September 2017. About 20 kg propellant was consumed for this manoeuvres leaving another 13 kg of propellant for its further mission life.

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