Some of the satellites that have survived are closer to Mars and they did not have the full view. Our orbit is bigger and we are able to take the full view of the planet,” he said. The imaging system is also able to map the topography through the dust clouds in Mars.

Chennai: India’s rendezvous with the red planet continues as its Mangalyaan (also known as Mars Orbiter Mission) completed four years in orbit on Sunday and in the process captured the seasonal variations of the planet for two Martian years. For a mission which was originally conceived for only six months, it is an achievement that all the five payloads of it is still functioning well.

The Rs 450 crore mission — hailed as cheaper than the Hollywood space movie Gravity - was launched with the PSLV-C25 rocket from Satish Dhawan Space Centre in Sriharikota on November 5, 2013. After crossing more than 66 crore kilometres in 300 days it entered into Mars orbit on September 24, 2014 thereby creating history for India as the first nation to reach Mars on a maiden attempt.

“MOM is taking pictures from a higher altitude where it captures the whole planet. With Mars Colour Camera, we are able to see the seasonal variations of Mars for two Martian years,” says Mylswamy Annadurai, former director of Isro Satellite Centre and who was programme director for the Mangalyaan project.

Isro also released a Mars Atlas with several images of the planet.

“Some of the satellites that have survived are closer to Mars and they did not have the full view. Our orbit is bigger and we are able to take the full view of the planet,” he said. The imaging system is also able to map the topography through the dust clouds in Mars.

Currently, Indian and international scientists are analysing the data for traces of Methane, a possible signature of life. “The Methane Sensor for Mars has sent the data and the scientists are currently correlating it to establish traces of Methane. It will take time,” Mr.Annadurai said.

How has the spacecraft which carried the small scientific payload survived this long?

The Mangalyaan spacecraft carried 100 kg fuel along with it for contingency and orbit corrections. “Whatever the fuel available to control the satellite, during our manoeuvres the fuel is not wasted. It was the primary reason why the mission life was extended to four years. The spacecraft still has fuel left,” says Isro chairman K.Sivan.

In its long journey so far, the spacecraft had survived the passing of comet Siding Spring, avoided a long eclipse that could have potentially exhausted its batteries and survived the communication blackout for a period of one month from June 2, 2015, to July 2, 2015, due to the solar conjunction.

During the solar conjunction, MOM was commanded with autonomy features without any ground commands or intervention. The long eclipse was avoided by a course correction, which reduced the eclipse period from as long as eight hours to zero.

Isro designed, built and launched the spacecraft in a record time of less than two years. How was that possible? “The hardware used for Chandrayaan-1 was used for Mangalyaan which has reduced time period. It also had the novel of idea ‘slingshot’ mechanism where it orbited earth to gain the speed to escape the earth’s gravitational pull,” scientists said.

While some sections viewed it as a costly advertisement to India’s space industry, scientists said it has enhanced the image of India among the space-faring nations.

“I had a personal experience how the image of India was changed after the success of Mangalyaan mission. There is a difference in how they viewed us before Chandrayaan-1, Mangalyaan and after the two missions. The international community is taking us seriously now,” Mr.Annadurai said.

The present Isro chairman K.Sivan also echoed it. “It gave the confidence to go on bigger missions. We also tested several technologies. We will soon launch a second mission to Mars and we are looking at the technical aspects of the project,” he said.

With heavier GSLV-Mk-III rocket now ready, it could carry a larger spacecraft with heavier scientific payloads to the Mars. “After the Chandrayaan-2, Isro's next scientific mission will be Aditya-L1 to study the Sun’s corona or atmosphere,” Mr.Sivan added. The mission will study why the sun’s atmosphere is hotter than the actual surface of the sun.