Insights into Editorial: Chandrayaan-2 lander: ISRO continues effort to contact Vikram
The Indian Space Research Organisation (ISRO) came tantalisingly close to creating history in the early hours of September 7 when the robotic lander Vikram followed the predetermined descent trajectory and came just within 2 km of the lunar surface before contact was lost.
While it is unfortunate that the lander failed to safely touchdown, it is apt to remember that ISRO was attempting powered landing for the first time.
To put it in perspective, there have been 38 attempts so far by other countries to land a rover on the moon and have succeeded only a little more than half the time.
This April, Israel’s Beresheet lunar lander crashed to the lunar surface.
But early January this year, China’s Chang’e-4 touched down on the lunar far side and deployed the Yutu-2 rover to explore the South Pole-Aitken basin.
Chandrayaan-2 was a highly complex mission:
- It represented a significant technological leap compared to the previous missions of ISRO, which brought together an Orbiter, Lander and Rover to explore the unexplored south pole of the Moon.
- This was a unique mission which aimed at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission.
- The Orbiter has already been placed in its intended orbit around the Moon and shall enrich our understanding of the moon’s evolution and mapping of the minerals and water molecules in the Polar Regions, using its eight state-of-the-art scientific instruments.
- The Orbiter camera is the highest resolution camera (0.3m) in any lunar mission so far and shall provide high resolution images which will be immensely useful to the global scientific community.
- The precise launch and mission management has ensured a long life of almost 7 years instead of the planned one year.
- The Vikram Lander followed the planned descent trajectory from its orbit of 35 km to just below 2 km above the surface.
- All the systems and sensors of the Lander functioned excellently until this point and proved many new technologies such as variable thrust propulsion technology used in the Lander.
- The success criteria were defined for each and every phase of the mission and till date 90 to 95% of the mission objectives have been accomplished and will continue contribute to Lunar science, notwithstanding the loss of communication with the Lander.
ISRO trying to establish communication with the Lander:
- In Vikram, the velocity was successfully reduced from about 6,000 km per hour at the start of the descent at 35 km altitude to a few metres per second(7.2Km/hr) before communication snapped.
- That strongly indicates that powered landing went as per plan till about 2 km altitude from the lunar surface.
- The more difficult part is to restore contact with the lander. That would depend on how much damage it has suffered, and whether its communication unit is intact.
- The individual instruments onboard the lander as well several of its components are capable of sending signals that can be picked up either through other nearby space assets or by the ground station.
- Every such signal will offer valuable clues to its current state and what it could have gone through.
- Indian Space Research Organisation (ISRO) chairman K Sivan was quoted as saying that the lander had been located on the Moon, and a thermal image of it had been taken by instruments on board the Chandrayaan-2 orbiter that is going around the Moon in a near-circular orbit of 100 km.
- It has been further said efforts to re-establish contact with the lander had not yet been successful.
- Vikram was designed to absorb the shock of an impact even at 5 metres/second (18 km/hr).
- At the rate it was decelerating, it could not even have attained a speed of 5 metres/second before touchdown.
- It is likely to have hit the Moon at a far greater speed, possibly damaging itself and instruments on board.
With the help of Orbiter:
The orbiter is safe in the intended orbit around the moon. And with the “precise launch and mission management”, its life span will extend to almost seven years.
Carrying eight of the 13 payloads, the orbiter will spend the next nearly seven years making high-resolution maps of the lunar surface, mapping the minerals, understanding the moon’s evolution, and most importantly looking for water molecules in the polar regions.
Some of the impact craters in the South Pole are permanently shadowed from sunlight and could be ideal candidate sites to harbour water.
Water on the moon would, in principle, be used for life support and manufacturing rocket fuel.
With the U.S. wanting to send astronauts to the South Pole by 2024, the National Aeronautics and Space Administration (NASA), in particular, will be keen on data from the Chandrayaan 2 orbiter.
Gaganyaan mission depends on Isro’s error-free control over launch of crewed spacecraft, ability to eject in case of faulty launch, wherewithal to support life in space and re-entry of the spacecraft into the Earth’s atmosphere.
Since the launch of Chandrayaan-2, not only India but the whole world watched its progress from one phase to the next with great expectations and excitement.
The ISRO’s Moon Impact Probe and NASA’s Moon Mineralogy Mapper on board Chandrayaan 1 had already provided evidence of the presence of water in the thin atmosphere of the moon, on the surface and below.
A NASA study last year found regions, within 20° of each pole in general and within 10° in particular, showed signs of water.
The Chandrayaan 2 orbiter will now possibly reconfirm the presence of water on the moon.
The science produced by the Chandrayaan-2 mission, too, might remain completely unaffected by what has happened to the lander, though the hype surrounding the landing attempt might not let people forget this failure very soon.
But there would also be very important learning for ISRO to be implemented in its future missions.