CHANDRAYAAN-2 MISSION: A SUCCESS IN FAILURES

For decades, the Moon has intrigued scientists for the possibility of the existence of water and life. Man has always dreamt to fly to the Moon in quest of establishing a home there. The first exploration of the Moon was carried out by the erstwhile Soviet Union’s unmanned Luna series of spacecrafts between 1959 and 1976 which achieved spectacular success from soft-landing to the returning of rock samples to Earth. However, the greatest feat in lunar exploration was achieved by the USA when it landed two humans on its surface in 1969.

Indian Lunar Mission

The objectives of Indian lunar mission are many aimed at technological demonstration and scientific achievements contributing to economic growth and national development. First, it is a tribute to Dr. Vikram Sarabhai, the Father of India’s Space programme by naming the Chandrayaan -2 Lander in his name on his birth centenary year. Secondly, the success would serve as a boost for the country’s upcoming Gaganyaan mission in 2022 where two Indians are slated to embark on a space flight mission to the low Earth orbit. Third, the success will be a stepping stone for ISRO to carry out more complex and challenging missions in future which may include manned flight missions to the Moon, landing on asteroids or Mars or sending unmanned spacecrafts to Venus or Mercury. Fourth, the mission will test many new technologies in space that would lead to self-reliance and development indigenous capability. It may be recalled that India originally signed an agreement with the Russian Federal Space Agency (Roscosmos) in 2007 to deliver the lander for Chendrayaan-2 and when Russia finally pulled out of the project citing financial constraints, ISRO went on to build its own Lander for the mission. Finally, it is expected that new technologies developed by ISRO for this mission would directly benefit common people or industries contributing to elevation of the quality of life and national progress. To illustrate how space technologies benefit society, the design of a space shuttle fuel pump developed by NASA can be taken for example which was later used as the basis of the design for a tiny heart pump for implantation in critically ill young patients.

India made a humble beginning in October, 2008 with the launch of Chandrayaan -1 that was basically an orbiter aimed at high resolution mineralogical and chemical imaging of the permanently shadowed North and South Polar Regions. A notable feature of this mission was an Impactor that detached from the orbiter and crashed on the lunar surface with a tricolor national flag enabling India to become the fourth country in the world after USA, Russia and Japan to have a touch-down on the Moon. Although the mission could not achieve its two year scheduled life span due to some technical snag, ISRO has almost accomplished most of its mission objectives and, more significantly, the analysis of findings of instruments owned by ISRO and NASA subsequently led to the discovery of water on the lunar surface.

Chanrayaan-2, launched by ISRO was an extension of India’s lunar mission and aimed at direct exploration of the Moon’s South pole which is hitherto untouched by any nation of the world. As per the mission goal, the Vikram Lander will separate from the Orbiter to have a soft landing on the Moon and from there; the Pragnya Rover will roll out to the vast desolated lunar surface for direct examinations of its rocks and soil. At the same time, the Orbiter will be busy at an altitude of 100 km in mapping the Moon for its treasure trove of mineralogical resources. The Mission has 13 payloads including one from NASA to conduct detailed study of Moon’s topography, mineralogy, surface chemical composition, thermo-physical characteristics and atmosphere leading to a better understanding of the origin and evolution of our closest celestial neighbour.

Chandrayaan-2 project started off well. The mission was launched on its course to the Moon from the second launch pad at Satish Dhawan Space Centre on 22 July, 2019 at 2.43 PM IST by a Geosynchronous Satellite Launch Vehicle (GSLV) Mark III . The craft reached the Moon's orbit on 20 August, 2019 and began orbital positioning manoeuvres for the landing of the Vikram Lander. Vikram and the rover were scheduled to land on the near side of the Moon on a smal patch of lunar highland smooth plains between Simpelius N and Manzinus C craters in the south polar region at a latitude of about 70° on the wee hours of 7 September, 2019 and conduct scientific experiments for one lunar day, which is approximately equal to two Earth weeks. However, the Lander, during the descent stage, deviated from its intended trajectory at nearly 2.1 km altitude and had lost communication when touchdown confirmation was expected. ISRO tried unsuccessfully to communicate with the Lander for two weeks before the lunar night set in.

Subsequently, Chandrayaan-2's orbiter reportedly spotted Vikram near the South Pole in the tilted position that confirmed its crash-landing on the Moon damaging the vital communication instruments. NASA's Lunar Reconnaissance Orbiter (LRO) passed over the landing site on 17 September and acquired a set of high resolution images of the area. Although NASA has not been able to precisely locate the position of Vikram in the lunar highland, a hard landing has also been suspected.

Payloads

ISRO selected 8 scientific instruments for the Orbiter, 4 for the Lander and 2 for the Rover. While it was initially reported that NASA and ESA would participate in the mission by providing some scientific instruments for the orbiter, ISRO in 2010 had clarified that due to weight restrictions it will not be carrying foreign payloads on this mission. However, in an update just a month before launch, an agreement between NASA and ISRO was signed to include a small laser retroreflector from NASA to the Lander's payload to measure the distance between the satellites above and the micro-reflector on the lunar surface.

Orbiter

1. Chandrayaan-2 Large Area Soft X-ray Spectrometer (CLASS) from ISRO Satellite Centre (ISAC), makes use of X-ray fluorescence spectra to determine the elemental composition of the lunar surface.

2. Solar X-ray Monitor (XSM) from Physical Research Laboratory (PRL), Ahmedabad for mapping major elements present on the lunar surface.

3. Dual Frequency L and S band Synthetic Aperture Radar (DFSAR) from Space Applications Centre (SAC), Ahmedabad for probing the first few meters of the lunar surface for the presence of different constituents, including water ice. DFSAR is expected to provide further evidence confirming the presence of water ice, and its distribution below the shadowed regions of the Moon. It has lunar surface penetration depth of 5 meters (L-band).

4. Imaging IR Spectrometer (IIRS) from Space Applications Centre (SAC) for mapping of lunar surface over a wide wavelength range for the study of minerals, water molecules and hydroxyl present. It features an extended spectral range (0.8 μm to 5 μm) which is an improvement over previous lunar missions whose payloads worked up to 3 μm.

5. Chandrayaan-2 Atmospheric Compositional Explorer 2 (ChACE-2) Quadrupole Mass Analyzer from Space Physics Laboratory (SPL) to carry out a detailed study of the lunar exosphere.

6. Terrain Mapping Camera-2 (TMC-2) from Space Applications Centre (SAC), Ahmedabad for preparing a three-dimensional map essential for studying the lunar mineralogy and geology.

7. Radio Anatomy of Moon Bound Hypersensitive Ionosphere and Atmosphere – Dual Frequency Radio Science experiment (RAMBHA-DFRS) by SPL for the studying electron density in the Lunar ionosphere.

8. Orbiter High Resolution Camera (OHRC) by SAC for scouting a hazard-free spot prior to landing. It will later help prepare high-resolution topographic maps and digital elevation models of the lunar surface. OHRC has spatial resolution of 0.3 m from 100 km polar orbit.

Vikram Lander

1. Instrument for Lunar Seismic Activity (ILSA) MEMS based Seismometer by LEOS for studying Moon-quakes near the landing site.

2. Chandra's Surface Thermo-physical Experiment (ChaSTE) Thermal probe by SPL, VSSC for estimating the thermal properties of the lunar surface.

3. RAMBHA-LP Langmuir probe by SPL, VSSC for measuring the density and variation of lunar surface plasma.

4. Laser Retro-reflector Array (LRA) by NASA's Goddard Space Flight Center for taking precise measurements of distance between the reflector on the lunar surface and satellites in lunar orbit. The micro-reflector weighs about 22 grams and can not be used for taking observations from Earth-based lunar laser stations.

Pragyan Rover

1. Laser induced Breakdown Spectroscope (LIBS) from Laboratory for Electro Optic Systems (LEOS), Bangalore.

2. Alpha Particle Induced X-ray Spectroscope (APXS) from PRL, Ahmedabad.

Vikram : A Success in Failure

Although the Vikram Lander of Chandrayaan-2, remained quiet as ISRO's chance of establishing communication link with the Lander has almost faded away because of the nightfall on the Moon paralyzing the onboard solar panel's power supply, the mission could not be labeled as a total failure. This is because the orbiter, carrying most of the instruments and payloads, is still active and has been orbiting the Moon in a polar orbit at an altitude of 100 km mapping the surface for its treasure trove of mineralogical resources. Out of the 13 payloads including one from NASA to conduct detailed study of Moon’s topography, mineralogy, and surface chemical composition, 8 are still working.

Although many nations of the world have sent missions to the Moon in past, soft-landing on the lunar surface has proved to be an uphill task. As the Moon has no atmosphere, the retro rockets have to be fired successfully to slow down the speed of descent so as to ensure a soft landing. Only three countries of the world i.e. United States, Russia and China have been able to demonstrate the technology and had India been able to execute the plan successfully, it would have been the fourth nation in the world to do so. It is hoped that ISRO, in subsequent missions, will master the soft landing technology and come out with a flawless execution of landing procedure.

It would be unfair to label this mission as a failure. The near success of Vikram’s landing should be acknowledged. It took the two space super powers, the United States and Russia, decades to design, plan and execute missions to the Moon. In fact, ISRO was founded shortly after the successful Apollo 11 mission to the Moon in 1969, and hence, it is a relatively young organization in the field. We should applaud the hard work of our scientists and engineers in the bygone 50 years of its existence. Many of our national leaders also, including Prime Minister Narendra Modi, had expressed full solidarity with the scientists of ISRO who spent many sleepless nights to make our dream come true.

Landmark Achievements

The achievements of the mission are many: First, the performance of ISRO's launch vehicle GSLV Mk-III was remarkable as it placed the craft neatly in orbit which will boost India’s future launch capabilities and interplanetary missions .Second, ISRO scientists managed a series of neatly executed manoeuvres all of which went smoothly as the orbiter reached the Moon’s orbit on the scheduled day as planned. Third, the two crucial phases of the soft landing were successful as only the third phase went wayward resulting in a hard landing. Fourth, given that the entire mission was highly complex and unique, ISRO has done a commendable job in boldly planning to send an orbiter to the Moon and soft landing with a Lander and Rover. ISRO claims to have accomplished 90 to 95 per cent of the mission objectives and vows to continue contributing to lunar science despite the loss of the Lander. Fifth, the orbiter camera is the highest resolution camera (0.3m) deployed so far in the world and shall continue to provide high resolution images to the global scientific community. Sixth, ISRO's precise launch and mission management had ensured an extended long life of almost seven years instead of the planned one year for the orbiter. Even the NASA and many of the world's leading space agencies complimented ISRO's attempt to land on the Moon’s hitherto unexplored and uncharted South Pole.

Many leading nations of the world have taken a number of missions to land on the Moon. USA, for example, took 11 missions to land humans on the Moon. The erstwhile Soviet Union, while at the peak of the space race in the sixties, took 9 Luna series of missions to soft landed on the Moon. Israel also suffered a setback in April 2019 when its spacecraft Bereshaft crash landed.

Although the setback of ISRO will not affect its future missions to the Sun and the Mars, it would have a definite bearing on its ambitious Gaganyaan project in 2022 where three humans are slated to be launched into space. As this is a manned mission intended to fly back the astronauts safely to Earth, the entire mission has to be executed in a flawless manner and no compromise is to be made with the safety of the astronauts. ISRO has to quickly analyze the shortcomings of the Chandrayaan-2 mission and bounce back to demonstrate the missing technology in space so as to ensure credibility and faith in the world community.