National Space Day: Learning about Moon through Chandrayaan-3 — It landed, hoped and slept but its journey will continue

India celebrated its first National Space Day on Friday, August 23. Exactly a year ago, on this day, India made history by becoming the first country to soft land on the Moon's south pole, thanks to the Chandrayaan 3 mission and the Indian Space Research Organisation (ISRO). To mark this landmark achievement, India will now celebrate National Space Day every year on August 23.

A throwback to India's Chandrayaan missions

It was five years ago, in 2019, when the Chandrayaan 2 mission lander's crash shattered millions of hopes. It was heartbreaking to see the then ISRO chief, K Sivan, breaking into tears. But the Chandrayaan 2 mission was a setback and not a total failure.

Fast-forward to August 2023. All eyes were on the follow-up Chandrayaan 3 mission. LVM3 M4 vehicle had successfully launched Chandrayaan-3 into orbit on July 14, 2023.

ISRO, under the leadership of S Somanath, took a few lessons from the Chandrayaan 2 mission to carry out the Chandrayaan 3 launch. Somanath said earlier that an image captured by the Chandrayaan-2 orbiter was used for "better identification of the locations" on lunar soil. The agency had also analysed failure scenarios, among other strategies, to soft-land the Chandrayaan 3 mission lander and rover on the lunar south pole.

The Indian space agency achieved the feat on August 23. "I reached my destination and you too!" The Chandrayaan 3 rover ramped down from the lander, and India took a walk on the moon on August 24, 2023.

VIDEO: Moment when Chandrayaan-3 soft-landed on Moon's South Pole:

Since then, Chandrayaan-3 mission has conducted groundbreaking experiments and led to insightful discoveries through three payloads on Vikram lander and two payloads on Pragyan Rover.

Here's all about the mission's key finding so far:

1. 70 degrees on Moon: The first observations came from the ChaSTE (Chandra's Surface Thermophysical Experiment) on August 27. The payload onboard the Vikram Lander measured the temperature profile of the lunar topsoil around the pole to understand the thermal behaviour of the Moon's surface.

ChaSTE payload has a temperature probe equipped with a controlled penetration mechanism, which is capable of reaching a depth of 10 cm beneath the surface. ISRO scientist BHM Darukesha had told PTI, "We all believed that the temperature could be somewhere around 20 degree centigrade to 30 degree centigrade on the surface but it is 70 degree centigrade. This is surprisingly higher than what we had expected.”

2. Sulphur confirmed on Moon: On August 28, ISRO said the Laser-Induced Breakdown Spectroscopy (LIBS) instrument onboard the rover made the first-ever in-situ measurements on the elemental composition of the lunar surface near the south pole.

"These in-situ measurements confirm the presence of Sulphur in the region unambiguously, something that was not feasible by the instruments onboard the orbiters," the space agency added. It said the investigation regarding the presence of Hydrogen on the Moon is underway.

According to ISRO, preliminary analyses unveiled the presence of Aluminum (Al), Sulphur (S), Calcium (Ca), Iron (Fe), Chromium (Cr), and Titanium (Ti) on the lunar surface. Further measurements revealed the presence of manganese (Mn), silicon (Si), and oxygen (O).

3. Minor elements on Moon: ISRO announced on August 30, 2023, that Alpha Particle X-ray Spectrometer (APXS) onboard the rover also "discovered the presence of interesting minor elements, including Sulfur, apart from the major expected elements such as Aluminum, Silicon, Calcium, Iron."

4. Sparse plasma: ISRO informed on August 31, 2023, that Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere - Langmuir Probe (RAMBHA-LP) payload onboard Chandrayaan-3 Lander conducted first in-situ measurements of the surface-bound Lunar plasma environment over the south polar region of the Moon.

"The initial assessment indicates that the plasma encompassing the lunar surface is relatively sparse, characterized by a number density ranging from approximately 5 to 30 million electrons per cubic meter," ISRO said.

5. Vibrations recorded: The Instrument for Lunar Seismic Activity (ILSA) payload on the Chandrayaan 3 Lander recorded the vibrations occurring due to the movements of Rover and other payloads. The vibrations were recorded during the rover's navigation on August 25, 2023.

6. A moonquake?: They payload also recorded "an event, appearing to be a natural one, on August 26, 2023." ISRO said the source of this event is under investigation. ILSA's objective is to measure ground vibrations caused by natural quakes (or moon quakes), impacts, and artificial events.

7. Unplanned ‘hop experiment’: The Vikram lander surprised the ISRO with its successful ‘hop experiment’. What's the significance? The ‘hop experiment’ or 'kick-start' "enthuses future sample return and human missions."

"Vikram soft-landed on 🌖, again!," ISRO exclaimed. It said, “On command, it fired the engines, elevated itself by about 40 cm as expected and landed safely at a distance of 30 – 40 cm away.”

8. Magma ocean on Moon?: Chandrayaan-3 moon mission recently found data that supports the theory that Earth's satellite was once covered in an ocean of magma.

Chandrayaan 3 lander and rover are now in sleep mode but…

…the journey will continue

India celebrated its first-ever National Space Day on Friday on the theme "Touching Lives While Touching the Moon: India's Space Saga".

Speaking at an event in New Delhi to mark the first National Space Day, Somanath said, "The journey of Chandrayaan 3 is going to continue... The model of Chandrayaan 4 is ready. We have proven how to reach Moon. But we have to prove now how to come back from there."