Were they really the debris of Indian moon lander Vikram as announced by the US space agency on Tuesday, wondered a senior official of the Indian space agency.
Interestingly, the Indian space agency Indian Space Research Organisation (ISRO) is maintaining a sound silence on the matter as there is no mention of the findings of NASA on its website or on its social media sites.
Releasing images of the lunar surface taken by its Lunar Reconnaissance Orbiter Camera (LROC), the US space agency National Aeronautics and Space Administration (NASA) confirmed that the debris of Vikram has been found.
The NASA had credited a Chennai based software professional Shanmuga Subramanian for positive identification of Vikram's debris.
ISRO's arguments
Meanwhile, Tapan Misra, Senior Advisor at ISRO studying the images released by the US space agency said: "Today NASA released LRO images of Chandrayan2 crash landing site. Very interesting images. Changed many conventional ideas, I had in my mind."
He said Vikram with partially burnt fuel must have had a mass of 700-800 kg (original weight was 1,471 kg), similar to that of a sedan car or a small aircraft. And as per ISRO data, it was travelling at a speed of 534 km per hour, speed of a jet aircraft.
"With this impact like jet crash on lunar regolith, a very fine dust of 0.5 m to 5-6 m thick covering of lunar surface, I expected a great upheaval in the first impact site, spreading around 10 m or more across."
"Almost like a small crater or dent. In fact, the dust or debris could jump up much more than on the earth, as lunar gravity is one sixth of that of the earth. But, surprisingly not a single change in dent one can see, except local brightness variation," Misra said.
Citing the unspent fuel on the lander, Misra expected some dark patches of burnt signs on the lunar surface as the fuel could have spilt on impact and burnt for a while since both -- fuel and oxidizer -- were present.
"But nothing like this is seen. Also, I expected some debris left behind at the first impact site. But, I could see none," Misra pointed out.
On the debris front, Misra also made another interesting point saying all the debris tended to get strewn, dominantly along a linear patch instead of getting strewn all around, considering randomness in rebounding of broken pieces after the first crash.
"During first impact at high speed, lander would have got compressed and broken. The stored energy because of compression would have got released next, by throwing away the broken pieces of lander in different arbitrary directions."
"Further all spacecraft components and structure elements are black painted. But looks like all the debris identified are shiny. I thought they should appear dark," Misra said.
Terming the NASA images as very educative for him, Misra added that common sense in engineering may differ widely with reality.
"These images are classic examples for the requirement of updating our understandings. Space Science does throw up many surprises which defy common sense," Misra concludes with a disclaimer that he was airing his personal views and have not drawn any conclusion leaving it for the readers to conclude.
Shanmuga Subramanian's identification
On Tuesday NASA said after receiving the positive tip from Chennai based Subramanian the LROC team confirmed the identification by comparing before and after images. When the images for the first mosaic were acquired the impact point was poorly illuminated and thus not easily identifiable.
"Two subsequent image sequences were acquired on October 14, 15 and November 11. The LROC team scoured the surrounding area in these new mosaics and found the impact site (70.8810 degree South, 22.7840 degree East, 834 m elevation) and associated debris field. The November mosaic had the best pixel scale (0.7 meter) and lighting conditions (72 degree incidence angle)," the US space agency added.
According to NASA, the debris first located by Subramanian was about 750 meters northwest of the main crash site and was a single bright pixel identification in that first mosaic (1.3 meter pixels, 84 degree incidence angle). The November mosaic shows best the impact crater, ray and extensive debris field. The three largest pieces of debris are each about 2x2 pixels and cast a one pixel shadow.
