Search for Vikram

It has been about 5 days since my last post here. When we last left Vikram, we had left it incommunicado close to the surface of the Moon.

Since then, there has been a lot of speculation with little or no information. There is no information from ISRO including what it seems to be doing now. Information is coming in at a tangent, from astronomers studying Doppler readings of the Lander and the Orbiter.

ISRO’s last official update (at the time of writing) states that it had located the lander and that it was trying to establish communication with it. There was a lot of speculation initially about the status of the lander. Many foreign observers (like Jonathan McDowell, Cees Bassa, Chris B etc.)said that the lander had very little chance of survival knowing the speed at which it was travelling at the time ISRO received the last telemetry from the lander. ISRO released information to some sections of the media (PTI report ) that the lander was intact but toppled. This was not found as an update on the ISRO website.

Science reporters then began to question ISRO’s claim that the mission was 90-95% success. Vasudevan Mukunth for The Wire considered the method by which they arrived at the success rate. Jacob Koshy writes in The Hindu with much more depth and history for the reasons why this quote now looks like a way to airbrush the failure. There has been no official response yet. S M Ahmed who had an instrument on board the Moon Impact Probe of Chandrayaan 1 discusses possibilities as to the fate of the lander on his blog.

The lack of information now has people studying the few statements that ISRO has already made. A story in India Today seems to re-interpret ISRO’s message to say that they were in touch with Vikram till about 400 m above the surface of the Moon and not 2.1 km like many media reports have since claimed.

Meanwhile, Ryan Watkins, a planetary scientist tweeted that NASA’s Lunar Reconnaissance Orbiter (LRO) will look for Vikram on September 17. LRO’s camera has a resolution of 0.5 m at an orbit of 100 km. It is believed that at this altitude, the images would not discern enough detail to let us know whether the lander is intact. There were reports that ISRO will lower the orbit of the Chandrayaan 2 orbiter to take a closer look. The orbiter has a camera with a better resolution than LRO. We got word from Edgar Kaiser, an amateur radio astronomer today that Chandrayaan 2 orbiter has now lowered its orbit above the South Pole.

Chandrayaan 2 orbiter orbit change detected on Doppler. Image: Edgar Kaiser

This seems contrary to rumours that K Sivan, ISRO Chairman has asked scientists to move on and focus on future missions. There were also some fairly stupid remarks from DRDO Chairman saying that PM Modi’s hug enabled ISRO to find Vikram.

While I’ve mostly given up on chances of locating Vikram intact we can await efforts from Deep Space Network (DSN) to hail the lander in hopes that it will be able to contact it.

Doppler seems to be bursting various balloons of hope that ISRO has created. It seems to be breaking news about the orbiter and lander. In space, you can’t lie. Covering up mistakes makes the situation much worse than needs to be.

Vikram Landing

Vikram is what ISRO calls the landing module of the Chandrayaan 2 spacecraft. The last we checked in on Chandrayaan 2, we witnessed the separation of the two modules of Chandrayaan 2. The orbiter module was in the correct orbit at the time of the separation.

Vikram then performed a couple of orbit lowering manoeuvre to reduce its orbit around 100 km by 30 km. As it approached the landing site, the spacecraft followed the desired trajectory through the rough braking phase where the speed of the vehicle was reduced drastically. All seemed to be going well up to this phase. The telemetry data sent back to ISRO Tracking Centre (ISTRAC) followed the mission plan.

The spacecraft then seemed to be deviating a bit from its track but seemed to be making an effort to return to the original path. The animation on the screen showed the spacecraft toppling over. It seems that Vikram was trying to stay in the correct orientation. At this point, ISRO said that they lost communication with Vikram at about 2.1 km above the lunar surface.

Doppler data from Vikram. Image: Cees Bassa, Dwingeloo Radio Telescope, Tweet.

We don’t have data as to what happened after this point. Doppler data received from Amsterdam’s Dwingeloo Radio Telescope was tweeted by Cees Bassa, an astronomer who was following Vikram at the telescope. This seems to show a “zoom” at the end which seemed to indicate a crash, according to him.

https://platform.twitter.com/widgets.js

ISRO’s own telemetry screen at the last available data point seems to indicate speeds which were considered too high for a proper landing to take place at the end. The above tweet is from Jason Davis of The Planetary Society who also has a good summary of events with some international context on their blog.

I was initially unhappy that the Prime Minister Narendra Modi walked away from ISTRAC letting ISRO Chairman K Sivan do the announcement. But, today morning he came back and with data announced that communication was lost. The data is still being analysed.

There are currently two orbiters in orbit around the Moon, Chandrayaan-2’s orbiter module and NASA’s Lunar Reconnaisance Orbiter. Each should be having an orbit around 2 hours and so might come over the landing site within this month and we should be able to have a look. This would give final confirmation on what happened early today morning.