Orbiter autonomy, navigation ability help ISRO win the day

To work around 40-minute communication delay, ISRO enabled orbiter to troubleshoot on its own

September 25, 2014 03:25 am | Updated November 17, 2021 11:06 am IST - BANGALORE:

The Mars Orbiter Mission (MoM) owes its success to three of its outstanding features: the India Space Research Organisation’s ability to accurately navigate the orbiter towards Mars through a “speedometer” distance of 65 crore km in space, ISRO’s expertise in deep space communication and the orbiter’s built-in autonomy that enabled the spacecraft to take decisions during contingencies. After the Polar Satellite Launch Vehicle (PSLV) put the Mars spacecraft into an earth-bound orbit on November 5, 2013, the ISRO navigated with finesse the spacecraft from its earth-bound phase to the sun-centric phase and then the final Martian phase. ISRO was, in other words, able to take the Mars orbiter through a radio distance of 22 crore km over a period of 11 months and successfully slip the orbiter into Martian orbit. As Prime Minister Narendra Modi said in his speech at the Mission Operations Complex-2 here on Wednesday, India successfully navigated the spacecraft “through a route known to very few”.

The huge distances in space entail a significant communication delay. It would take around 20 minutes for a command from ground control to reach the spacecraft and another 20 minutes for telemetry information about the health of its systems to be fed back: a round-trip delay of 40 minutes. Communication with the spacecraft will was carried out from the MOC-2 and the indigenously-built 30m-diameter antenna installed at Byalalu village near here. To help work around the delayed communication, ISRO equipped the orbiter with the autonomy to take decisions to set anomalies right on its own rather than wait for commands from the ground. The orbiter has sensors and transmitters that can sense “misbehaviour” and switch over to the redundant system on its own. As ISRO chairman K. Radhakrishnan stressed earlier: “If one were to identify two important elements in the Mars orbiter, it is its autonomy and navigation towards Mars.”

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