Chennai: A Chennai techie, Mr Shanmuga Subramanian, has helped Nasa (National Aeronautics and Space Administration) identify the spot where the Vikram lander of Chandrayaan-2 crashed on the moon’s surface, the US space agency confirmed on Tuesday. The lander had crashlanded on September 7.
Mr Subramanian had first spotted it on October 3, and tweeted the location on November 17. The tec-hie said Nasa had credited him with finding the debris of the lander based on his analysis of Nasa images of the lunar surface.
He went through Nasa’s Lunar Reconnaissance Or-biter Camera (LROC) ima-ges “pixel by pixel” to identity a single bright pixel from its mosaic taken on November 11 and e-mailed his conclusion to both the Nasa and Isro.
While Nasa agency responded after a delay, with an apology. There was silence from Isro.
“I went through the LROC images pixel by pixel and found some minute variations at a spot on the lunar surface between the image of December 2017 and the one taken on September 17. I sent my finding to Nasa and what they did was to closely search the lunar surface based on the location I gave and pick up the location of the larger deb-ris,” Mr Subramanian told DC, amid the tight stream of media interviews at his Besant Nagar apartment.
Nasa’s LROC team had released the first mosaic of images acquired during its September 17 flyby of the Moon on September 26, and invited people to compare it with images of the same area before the crash to find signs of the lander.
Two subsequent image sequences were acquired on October 14 and 15, and November 11, PTI reported
Mr Subramanian tagged the Twitter handles of Nasa and Isro in a tweet on October 3, and asked, “Is this Vikram lander? (1 km from the landing spot) Lander might have been buried in Lunar sand?”.
On November 17, he zeroed in on his observations and tweeted out the possible crash site of the lander. “This might be Vikram lander’s crash site (Lat:-70.8552 Lon:21.71233) & the ejecta that was thrown out of it might have landed over here (The one on the left side was taken on July 16th & one on the right side was from Sept 17),” he said in a tweet accompanying the images. He was spot on.
From the two LROC images, Mr Subramanian could point out to Nasa that a 2017 image he analysed had no white dot whereas the September 2019 image had it at that spot, and that could only mean that it was Vikram lander. It was visible only as a dot because of the resolution of 1.25 metre per pixel.
“I saw the internet landing location. From Vikram lander’s last known location, I knew it must be somewhere around that. I searched the 2x2 km sq area pixel by pixel. Since the lander was so small, I had to search each and every pixel. I was able to find something out of ordinary over there and I sent out a mail to Nasa”, he said.
Nasa, which has been closely following the mission, as also several international agencies, collaborated in the Isro search for clues about the lander’s whereabouts. Nothing much happened, until Mr Subramanian’s mail landed with the two space agencies.
“I feel happy I could find the debris. I had worked for close to seven hours every day for a week (49 hours), going through the LROC images from Nasa. It was worth it,” Subramanian said.
“Thank you for your email informing us of your discovery of debris from the Vikram lander. The LROC team confirmed that the location does exhibit changes in images taken before and after the date of the landing,” said deputy project scientist Lunar Reconnaissance Orbiter mission John Keller, according to PTI.
“Using this information, the LROC team did additional searches in the area and located the site of the primary impact as well as other debris around the impact location and has announced the sighting on the Nasa and ASU pages where you have been given credit for your observation,” he said.
