Shanmuga Subramanian On How He Helped NASA Find Lander Vikram's Debris

NASA on Tuesday said it had found Chandrayaan-2 ′s Vikram lander, which crashed on the surface of the Moon in September. The US space agency also shared images of the “impact point and associated debris field” and credited Chennai techie Shanmuga Subramanian with identifying the debris. 

The Indian Space Research Organisation (ISRO) had attempted a soft landing on the lunar surface on September 7, but the ground stations lost communication with Vikram after the launch.

“The Chandrayaan2 Vikram lander has been found by our NASA Moon mission, the Lunar Reconnaissance Orbiter. See the first mosaic of the impact site,” NASA said in a tweet.

The US space agency had released high resolution images captured by LROC during its flyby on 17 September and said that the team was not able to locate the lander  then.

Subramanian, however, confirmed the identification of the crashing site of Vikram by comparing before and after images. “After receiving this tip, the LROC team confirmed the identification by comparing before and after images,” NASA said in a statement.

How did Subramanian locate the debris?

Talking to IANS , he said, “It was something challenging as even NASA can’t find out so why can’t we try? That’s the thought that led me to search for Vikram lander.”

He told The New York Times that for the first few days, he would scan the images randomly and got a lot of false positives. He noticed a white speck on the lunar surface about two-thirds of a mile from where Vikram was supposed to have landed. That speck was not visible in an earlier image.

“I had side-by-side comparison of those two images on two of my laptops... on one side there was the old image, and another side there was the new image released by NASA,” he told AFP , adding he was helped by fellow Twitter and Reddit users.

“It was quite hard, but (I) spent some effort,” he said, announcing his discovery on Twitter on October 3.

Subramanian tagged the twitter handles of NASA, LRO and ISRO in a tweet and asked, “Is this Vikram lander? (1 km from the landing spot) Lander might have been buried in Lunar sand?”.

On November 17, he further 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.

Subramanian, in an interview to The News Minute , said he compared picture by picture for almost a week and would do it for seven hours a day. 

The LROC team confirmed the identification after receiving the tip from Subramanian. 

“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,” deputy project scientist Lunar Reconnaissance Orbiter mission John Keller was quoted as saying by 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,” Keller said.

(With PTI inputs)