# Why would thermal imaging be used to locate the Chandrayaan-2 lander?

Tweets and news suggest that Chandrayaan-2 lander may have been located, using thermal imaging by the Chandrayaan-2 orbiter.

• K Sivan, chief of the Indian Space Research Organisation, said today (Sept. 8) that the Vikram lander was located by Chandrayaan-2 and efforts to restore contact the probe will continue for at least 14 days, according to a Times of India report.

"We have found the location of Lander Vikram on [the] lunar surface and Orbiter has clicked a thermal image of Lander," Sivan told the ANI news service in an interview, adding that attempts to communicate with the lander are ongoing.

• n an exclusive interview, ISRO Chairman K. Sivan told India Today TV that the Chandrayaan 2 orbiter had sent back a thermal image of the location of the Vikram lander, and they're now attempting to contact it.

• Asian News International: tweet

Indian Space Research Organisation (ISRO) Chief, K Sivan to ANI:We've found the location of #VikramLander on lunar surface&orbiter has clicked a thermal image of Lander. But there is no communication yet. We are trying to have contact. It will be communicated soon. #Chandrayaan2

• K. Sivan, the director of the Indian Space Research Organization, told national news outlets that a thermal image had been taken by the Chandrayaan-2 mission’s orbiter. He said it was still unclear whether the lander was damaged, though he expected it had experienced a “hard landing.”

“We are trying to establish a contact,” he was quoted as saying by Asian News International.

The thermal image from the orbiter has not been released publicly. A spokesman for the space agency did not respond to requests for comment on Sunday.

Question: Why a thermal image? Is there expected to be better contrast than in visible light? Does Chandrayaan-2 not have a visible light camera? Wouldn't the diffraction-limited resolution at thermal infrared (5-20 microns) be much worse than in the visible (0.4-0.7 microns)?

• the ANI report (non tweet): aninews.in/news/national/general-news/… – amI Sep 9 '19 at 15:55
• While it appears to be a false report it does make sense. The lander would have a bunch of fuel on board, rockets have a considerable tendency to fireball if they break up. If it went down in a shady spot I would expect that spot to be warmer for a bit. – Loren Pechtel Sep 10 '19 at 2:53

It was not a thermal image at all.

It is an optical image that has been captured by Orbiter of the lander spot and not thermal image as reported by others media houses. OHRC is same like our human eye. Since it consists of only one spectral band in visible region, so Image will be of gray scale, Not color image.

ISRO Sources confirms me that "Lander found 500m away from the actual landing spot. Seen from OHRC (Optical High Resolution Camera) image and it is intact. Trying to send commands from Bangalore control center." @ABPNews

There are many fake images going viral claiming to be of "Lander Spot on Lunar surface" clicked by Orbiter. FYI, No such image has been released by @isro so far.

It is noticed that accounts in the name of Kailasavadivoo Sivan is operational on many Social media. This is to clarify that Dr. K Sivan, Chairman, ISRO does not have any personal accounts.

For official accounts of ISRO, please see https://bit.ly/2lHe9GT

There are some articles trying to "sell" what looks like a thermal image of the lander (I would prefer not to link it), but in one case the image shows almost half of the Moon, so has no resolution to represent what it says it does, and a second one is some kind of closeup (if real at all), possibly made just after separation of the lander.

• Well that certainly explains a lot! – uhoh Sep 9 '19 at 13:36
• I've added a supplementary answer. Thanks for all the great links! – uhoh Sep 9 '19 at 13:50

As is pointed out there, there seems to be an abundance of false social media accounts claiming to be K. Silvan.

From today's Sep 09, 2019 post: Regarding Social Media Accounts in the name of Kailasavadivoo Sivan, Chairman ISRO:

It has been noted that social media accounts in the name of Kailasavadivoo Sivan (along with photographs of K. Sivan) is operational and active on social media platforms. This is to clarify that K. Sivan, Chairman, ISRO does not have any personal account on any social media platforms. Hence all the information on all such accounts are not authentic.

The official account of ISRO on all social media platforms are as follows:

According to the latest Sep 07, 2019 update: https://www.isro.gov.in/update/07-sep-2019/chandrayaan-2-latest-update Chandrayaan-2 has an extremely nice visible light telescope with a 30 centimeter aperture! At 0.5 microns wavelength, $$1.22 \lambda / d$$ would provide a resolution of about 0.4 arcseconds. At a minimum distance of 100 km that would be a resolution of about 20 cm.

Chandrayaan-2 mission was a highly complex mission, which represented a significant technological leap compared to the previous missions of ISRO, which brought together an Orbiter, Lander and Rover to explore the unexplored south pole of the Moon. Since the launch of Chandrayaan-2 on July 22, 2019, not only India but the whole world watched its progress from one phase to the next with great expectations and excitement. This was a unique mission which aimed at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission. The Orbiter has already been placed in its intended orbit around the Moon and shall enrich our understanding of the moon’s evolution and mapping of the minerals and water molecules in the Polar Regions, using its eight state-of-the-art scientific instruments. The Orbiter camera is the highest resolution camera (0.3m) in any lunar mission so far and shall provide high resolution images which will be immensely useful to the global scientific community. The precise launch and mission management has ensured a long life of almost 7 years instead of the planned one year. The Vikram Lander followed the planned descent trajectory from its orbit of 35 km to just below 2 km above the surface. All the systems and sensors of the Lander functioned excellently until this point and proved many new technologies such as variable thrust propulsion technology used in the Lander. The success criteria was defined for each and every phase of the mission and till date 90 to 95% of the mission objectives have been accomplished and will continue contribute to Lunar science , notwithstanding the loss of communication with the Lander.

It's unusual for the New York Times to get things wrong, but reading carefully they are quoting other news outlets, not K. Silvan directly.