BackA giant leap for Isro
Over the last four decades, Isro been on a march towards self-reliance with the vision of harnessing space technology to meet societal needs
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Over the last four decades, the Indian Space Research Organisation (Isro) has developed capabilities in building, launching and operating satellites to address the remote-sensing, weather-monitoring and communication-navigation needs of the country, step by step. It has been a march towards self-reliance in these fields with the vision of harnessing space technology to meet societal needs. Spacecraft monitoring and control, ground segments development, building applications-driven passive and active imaging and non-imaging Earth observation systems and satellite-based communication infrastructure have been the building blocks that have led to advancing the nation’s space programme.
Today, India is considered a leader in Earth observation and is striving to provide weather monitoring, communication and navigation capabilities.
When Isro devised its first planetary exploration mission—Chandrayaan-1—it set a new boundary of 384,000km, i.e. a 10-fold increase in distance from the previously achieved distance of 36,000km needed for geostationary functionality of communication satellite missions.
Isro successfully put the Chandrayaan-1 spacecraft in lunar orbit at a distance of 384,000km and achieved the 100km circular orbit around the moon. The success of the mission—in terms of launch, spacecraft control and manoeuvring, payloads operation and reception of volumes of good quality data—has strengthened Isro’s confidence in taking up tasks of high complexities.
The present Mars Orbiter Mission demands going a further 700 times longer distance (about 250 million km) compared to the Chandrayaan-1 mission, and hence poses many technological challenges with respect to the distance required to be covered to reach its destination.
The Mars Orbiter Mission is essentially a technology demonstration mission for Isro, involving carrying the Mars Orbiter out of the sphere of the Earth’s gravitational influence travelling about 250 million km, where the spacecraft will be subject to gravitational influence of other planets. At the end of this journey, the spacecraft needs to be in a cube of 50km at a distance of 500km from Mars’ centre at a specified date and time.
The spacecraft will then be reoriented and the thrusters onboard the satellite fired to reduce its velocity so as to achieve an elliptical orbit around Mars.
During its revolution around Mars, the spacecraft could encounter black-out periods in the shadow of the planet where it will be blocked from using solar energy. There will be periods of white-outs when the spacecraft will be unable to communicate to ground control. A spacecraft that is meant to travel such a long distance through extreme space environments needs to have in-built autonomy and intelligence to tackle contingencies. In such a situation, autonomy puts the satellite into “safe mode" so that the ground controllers can set it right. The Mars Orbiter Mission spacecraft is equipped with systems to react in such eventualities.
Communication with the spacecraft throughout the mission and with the payloads after deployment remains a key element in such long-distance space missions. The ground setup already in place—used for its moon mission—at the Indian Space Science Data Centre (ISSDC) near Bangalore, Isro will meet this critical requirement of communicating with the satellite in association with other deep space communication stations in different parts of the globe for the successful realisation of the mission.
Once the spacecraft reaches Mars, all the five indigenously built payloads on board will conduct different experiments. The methane sensor will trace the methane origin. Two more instruments will study the escape processes of hydrogen/deuterium; and a Mars colour camera will gather information about Martian topography. Due to stringent requirements of the mission in terms of mass, electrical and electronics, optics, a lot of miniaturisation has taken place.
Succeeding in missions of such complexities will pave the way for applying these advanced technologies in Isro’s other regular ongoing missions in remote-sensing, weather-monitoring and communication-navigation, making them more autonomous. On the ground, these missions will not only help give a tremendous boost to the enthusiasm and collective confidence of the workforce at Isro, but also evoke interest among the scientific and student community in space-based research, exploration and application activities.
A.S. Kiran Kumar is a distinguished scientist and director of the Space Applications Centre (SAC), Ahmedabad.
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