With the Chandrayaan-3 Lander and Rover being induced into sleep mode on the moon after the Indian Space Research Organisation (ISRO)’s successful landing mission, scientists have said the mission’s objective has been completely met and even exceeded expectations.
Late on Saturday, ISRO announced sleep mode had been induced for the Pragyan rover that roamed a distance of over 100 metre on the moon, after emerging from the Vikram lander on August 23, around three hours after landing on the moon at 6.03 pm IST.
“Our scientific objective is completely met and in fact, it exceeded our expectations and this is why we are all very happy. Our director of URSC and chairman Isro and all centre directors who have been guiding us are all very satisfied,” the project director for the Chandrayaan-3 mission P Veeramuthuvel said ahead of the induction of the sleep mode for the lander.
Veeramuthuvel indicated Vikram would also be commanded to go into sleep mode on Sunday. Although the mission life is 14 earth days (one day of sunlight on the moon) all of them cannot be utilised, he said.
“We landed on the second day (of sunlight on the moon). There are 14 days of sunlight but we cannot fully utilise these 14 days because we had to have a sun elevation angle of six degrees. So, we cannot go till the 14th day and we will be planning to issue the sleep command sometime tomorrow (Sunday),” Veeramuthuvel said.
The optimum sun elevation angle of six degrees is not available through the 14 days of sunlight on the moon where the sun elevation is lower than six degrees at the beginning and end of the lunar day.
“Sleep has to be commanded. Our mission life as per the plan is one lunar day which is equivalent to 14 earth days. Our entire design is for that. We have built in a very innovative feature of sleep and wake up and if it survives in the lunar night where temperatures go down to a very low level of upto minus 150 degrees Celsius, there is no guarantee that systems will work but we are having hope. That is all,” added Veeramuthuvel.
On Saturday, ISRO had said on its social media accounts, “The solar panel is oriented to receive the light at the next sunrise expected on September 22, 2023. The receiver is kept on. Hoping for a successful awakening for another set of assignments! Else, it will forever stay there as India’s lunar ambassador”.
Veeramuthuvel said the three science instruments on Vikram and the two on Pragyan had collected a “wealth of data” on the surface of the moon which scientists will be studying for new findings that will emerge in the coming days.
According to the project director, the Chandrayaan-3 mission surmounted multiple challenges from the stage of preparing for the project to the final landing and the carrying out of experiments.
“I cannot name one or two because there were many, many challenges. Starting from the time of preparing for the project we had to conduct ground tests by recreating the moon environment. This was a challenge as we had to prove working in the moon environment. We needed to have the right test configuration, the number of tests and the results had to be right. The tests have to be subjected to review,” Veeramuthuvel said.
“Landing was a very, very big challenge. After the launch every stage was a challenge – raising the orbit, leaving the earth’s orbit, acquiring the moon’s orbit and then lowering to a circular orbit and finally deboosting, separating of orbiter from the lander and finally coming to the elliptical 100×30 orbit and again descending from there for the final 30 km,” he said.
“The last 19 minutes were the biggest challenge because it was a fully autonomous landing sequence,” the Chandrayaan 3 project director said.
After the landing on the moon there were new challenges like the “deployment of all the deployable elements,” he said.
“The rover has to come onto the lunar surface. The rover has to have mobility. The mobility is a semi-autonomous operation and along with this, it has to go around the moon and give the data to ground through the lander. The rover does not have direct communication with Earth and it has to come via lander,” added Veeramuthuvel
“The rover has to avoid obstacles as it roams. There are limitations in the movements of the rover and there are so many payload data that have to be operated. After all, we went to the moon to conduct surface experiments and these surface experiments have to be done and our time is very limited. We have been working 24×7 on this,” he said.
Since the picture-perfect landing of the Lander Module on August 23, the different stages of ISRO’s first landing mission on the moon have gone as planned.
“Of the mission objectives – demonstration of a Safe and Soft Landing on the Lunar Surface is accomplished, demonstration of Rover roving on the moon is accomplished and conducting in-situ scientific experiments is underway. All payloads are performing normally,” the space agency had stated three days into the mission on August 26.
