Chandrayaan-3 lander Vikram comes up with a surprise, makes a ‘jump’ on the Moon

“Vikram Lander exceeded its mission objectives. It successfully underwent a hop experiment. 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,” ISRO said in a statement.

Moon lander where it touched down on August 23; (right) at the new location after the “hop” on Monday. (Source: ISRO images)

The ‘hop experiment’ came as a surprise. ISRO had never mentioned this plan earlier. Although it was a very small jump, it represented a significant and exciting step forward. It demonstrated ISRO’s capability to get the lander to fire its engines and produce the thrust to lift it off the ground.

Chandrayaan-3 Mission:
🇮🇳Vikram soft-landed on 🌖, again!

Vikram Lander exceeded its mission objectives. It successfully underwent a hop experiment.

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.… pic.twitter.com/T63t3MVUvI

— ISRO (@isro) September 4, 2023

This capability is key to future lunar missions when ISRO would want the spacecraft to return with samples from the Moon, or when it plans to land human beings on the Moon. In those instances, the lander would have to make a lift-off from the lunar surface and return to Earth. Of course, the thrust required in those situations would be much higher. But as a technology demonstration, the ‘hop experiment’ would remain one of the highlights of the Chandrayaan-3 mission.

“This ‘kick-start’ enthuses future sample return and human missions,” ISRO said.

The second soft-landing, as ISRO described it, was very different from the first one. The nearly 1,750-kg lander was slightly lighter than the previous time, with the 26-kg rover having come out. That would also have changed the distribution of weight inside the lander.

Though ISRO is yet to announce follow-up missions to the Moon, scientists have told The Indian Express that a sample return mission was the next logical step to Chandrayaan-3. In fact, if Chandrayaan-2 had been successful in 2019, Chandrayaan-3 would have been a sample return mission. The human lander mission would also come at a later point.

The Chinese Chang’e lunar programme has also progressed on similar lines. China sent an orbiter, its first lunar mission, in 2007, and then followed it up with a lander and sample return mission, the last one in 2020.

ISRO said the spacecraft and the instruments onboard were all working fine after the ‘hop’. “All systems performed nominally and are healthy. Deployed ramp, ChaSTE and ILSA (instruments) were folded back and redeployed successfully after the experiment,” it said.

Chandrayaan-3 Mission:
Vikram Lander is set into sleep mode around 08:00 Hrs. IST today.

Prior to that, in-situ experiments by ChaSTE, RAMBHA-LP and ILSA payloads are performed at the new location. The data collected is received at the Earth.
Payloads are now switched off.… pic.twitter.com/vwOWLcbm6P

— ISRO (@isro) September 4, 2023

The ramp was used by the rover, which was initially held inside the lander module, to slide down on the lunar surface, while ChaSTE and ILSA instruments had their components poking out of the lander and touching the lunar surface to carry out their experiments. These instruments folded themselves up and then re-deployed themselves after the ‘hop’.

Shortly thereafter, the payloads onboard the lander were put to sleep in preparation for the incoming night time, but not before they carried out observations at the new location.

Trying to extend the life of the Chandrayaan-3 instruments to the second lunar day is also a plan that was not disclosed by ISRO earlier. The mission life of both the lander and rover was supposed to be only one lunar day, equivalent to 14 days on Earth. The solar-powered instruments were not designed to survive the extreme low temperatures of lunar night, which drops well below -120 degree Celsius.

But soon after the launch of Aditya-L1 mission on Saturday, ISRO Chairman S Somanath announced plans to try and extend their life. As a result, the instruments onboard the rover were put in sleep mode on Saturday, a few days earlier than the beginning of the night-time. The remaining battery would try to keep the instruments warm during the night-time, which too extends for 14 Earth days. If the battery does not completely drain during this time, the instruments can become active once again when sunshine becomes available.

The instruments onboard the lander were put to sleep on Monday. “Vikram Lander is set into sleep mode around 08:00 Hrs. IST today. Prior to that, in-situ experiments by ChaSTE, RAMBHA-LP and ILSA payloads are performed at the new location. The data collected is received at the Earth. Payloads are now switched off. Lander receivers are kept ON. Vikram will fall asleep next to Pragyan once the solar power is depleted and the battery is drained. Hoping for their awakening, around September 22, 2023,” ISRO said.

After the Moon landing on August 23, ISRO has begun calling the lander module by its name ‘Vikram’ , and rover by the name ‘Pragyan’ on social media. It used to refer to it as just ‘lander module’, or LM, and rover earlier. Vikram and Pragyan were names given to the lander and rover on Chandrayaan-2 that failed to make a soft landing in 2019. ISRO had not named the lander and rover on Chandrayaan-3. In all official documents on the ISRO website, these are still referred to as lander module (LM) and rover.