Japan's Lunar Lander Official Update
Guys, earlier I had mentioned that I was waiting for my favorite space blogger, Scot Manley, to tell us what happened to the Japanese Lunar lander. Here it all is. In tremendous detail. His easy-going style and Scottish accent make this 14-minute summary worth seeing.
A couple of key observations. Incredibly, we have an actual photograph of the lander. (I’ll tell you how they got it) lying upside down on the moon. Note the engines and attitude control thrusters pointing up.
The picture was taken by one of two companion miniature rovers successfully ejected from the spacecraft seconds before it arrived on the Moon, just in time to dramatically document the situation with its camera high-definition camera.
Even though the spacecraft is resting “Flaming Side Up” (spacecraft jargon), it touched down gently and everything seems to be functioning. A key exception is the solar panels which are not properly oriented to the Sun. We must wait until the next lunar sunrise to see if they come alive. Fingers crossed. Altogether, Japan met its key mission requirements in that, upside down or not, it is alive and within the small landing zone intended. This was the principal objective they were hoping to achieve.
So what went wrong? The telemetry data below shows, second by second, the thrust of the pair of descent engines as they approached the Moon. The red arrow shows where the combined thrust dropped to about half its previous level. This is the point where one of the descent engines lost its nozzle. Then the green lines climbed back up dramatically as the onboard flight software made desperate corrections for the thrust loss by giving it everything it had ….. and achieving an in-spec soft landing.
Unfortunately, there was also quite a bit of sideways thrust as well, which caused the spacecraft to tip over. It is important to note that the Japanese flight software was agile enough to respond on its own (like a fighter pilot who has just lost an engine) to the nozzle loss without any inputs from Earth (which is not possible because things were happening so fast and there is a delay in data and command signals between the Moon and Earth).
How do we know an engine nozzle was lost? Well, we got a photograph of that as well. The downward-looking descent cameras saw it fall to the lunar surface just before touchdown. There it is with a red circle around it. Also, it is gone in the later picture taken by the small companion lander.
Here is a link to some more videos speculating on what was happening before the recent press conference. Much less data to go on, but interesting.
