ISRO & odyssey to the Moon

Dr Vikram A Sarabhai, the father of Indian Space programme, whose birth centenary was celebrated on August 12, visualised the space technology to be used for a common man by providing communication, remote sensing and broadcasting for societal applications. He also envisioned the development of launchers for satellite launching from Indian soil. ISRO achieved more than Dr Sarabhai's expectations by launching and operationalising a large constellation of communicational satellites, remote sensing and scientific satellites. Today, India maintains the largest constellation of remote sensing satellites in the world.

Prof Sarabhai did not envision going for interplanetary missions and missions to Moon. ISRO surpassed his expectations by launching Chandrayaan 1, Mars Orbiter and the story continued with the Chandrayaan 2. An ambitious project where the Orbiter plus lander Vikram and Rover Pragyan together weighing around 4 tonnes were launched by GSLV MARK 3. The mission is the successor of Chandrayaan 1, where a small capsule was put on Moon surface and Mars orbiter was put in Mars orbit in the first attempt.

The successor of the Chandrayaan 1, the Chandrayaan 2, was planned:

To develop and demonstrate the key technologies for end-to-end lunar mission capability, including soft-landing, and roving on the lunar surface.

To expand the lunar scientific knowledge through a detailed study of topography, mineralogy leading to a better understanding of the origin and evolution of the Moon.

It is worth recalling here that the presence of water was detected by Chandrayaan 1.

Chandrayaan 2, the combined payload entered into the Moon's orbit successfully on the planned dates and all the complex and critical operations of reducing the orbit height to 100kms*100kms, separating Vikram the lander and deboosting it to 30kms*100kms orbit, was a great feat attained in a professional manner by the most optimum fuel use. Early morning of September 7, 2019, the critical manoeuvering of further deorbiting Vikram for soft landing on the south pole was initiated around 1:30 am. The hard breaking manoeuvering was done successfully while during the soft breaking the lander reached at a height of 2.1 km and apparentaly due to some guidance and control manoeuver malfunctioning, soft-landing could not be achieved.

The orbiter is successfully orbiting the Moon in it's designated orbit. It has got 8 payloads onboard:

Chandrayaan 2, large area soft X-ray spectrometer to map the abundance of the major rock forming elements like Magnasium(Mg), Silicon(Si), Aluminium(Al), Calcium(Ca), Titanium(Ti) and Iron(Fe) at a special resolution of 12.5 km using the technique of X-ray Fluorescence.

X-ray solar monitor to study X-rays emitted from Sun and Sun corona to support the first experiment.

Dual Frequency Synthetic Aperture Radar to study the surface features of Moon, especially the polar regions which will help in studying the water presence in craters.

Infrared Spectrometer to image the Moon surface in 0.8 to 5 microns to investigate and identify minerals and detect water molecules in polar regions.

Chandra's Atmospheric Composition Explorer (CHACE-2): It is a Neutral Mass Spectrometer which will study the lunar exosphere.

Terrain Mapping Camera: Which has three camers fore, nadir and aft for preparing 3-D maps of Moon surface.

Dual Frequency Radio Anatomy of Moon bound hyper sensitive ionosphere and atmosphere probe: To measure the total electron contents of the lunar ionosphere and its morphology.

Optical High Resolution Camera: To provide high-resolution images of the Moon.

Unfortunately, lander and rover which had together 6 payloads will not be working, but the outcomes of 8 experiments on board orbiter will enhance the knowledge of human race about overall geology, minerology and atmosphere of the Moon. The detection and estimation of water in polar regions and the high resolution images will provide valuable inputs to the future researches who may in future like to land on the polar region or colonise it. The excellent performance of orbiter and functioning of its payloads ensures the fulfilment of more than 60% of the mission objectives.

The experience gained in launching the composite Chandrayaan 2 and raising its orbits in a phased manner with utmost reliability and accuracy with the economic use of fuel and bringing it in first attempt to lunar orbit and further deboost operations have increased our knowledge towards handling such critical manoeuvers. This will be very useful for future interplanetary and lunar missions. The experience gained is invaluable.

If one takes an integrated view, the various technologies and softwares developed by the ISRO and industries have increased our confidence and skills for repeating such missions and using those things for civilian and defence uses.

The money spent (Rs 978 crore) is much less than the one spent by other agencies. Majority of this money has been given to industry and developing the infrastructure. This way we can say that more than 80% of the mission's objectives have been achieved which is usually a very positive result/return. ISRO scientists and people working in various industries like HAL, BEL, L&T and a large number MSME's deserve to be congratulated. The country feels very proud of the scientists and their achievements.

It is heartening to note that the honourable Prime Minister stood with us strongly and applauded the achievements of ISRO. The whole ISRO community is greatful to the country and the Prime Minister for excellent support in the need of hour.

The author is a former vice chancellor of Defence Institute of Advance Technology, Pune, a S Dhawan professor and a senior adviser at SATNAV-ISRO, Bengaluru