And with that I think we will close our examination of Lunokhod 2, a remarkable mission in many ways. This was only the second time any vehicle had been driven remotely on another world (the first being Lunokhod 1), and I would rank them and the sample return missions as the greatest achievements of the Soviet Union in lunar exploration, on a par with their Venus results and far beyond what they accomplished at Mars.

Tomorrow... another orbiter.
#moon #luna21 #lunokhod2

Early in our Lunokhod 2 sequence i gave a link to the Lunokhod 2 panoramas. Here is one of them:

https://www.planetology.ru/panoramas/images/big/lunokhod2_c/L2_D03_S05_P14m.jpg

Day 3, session 5, pan 14... it was taken at the south end of the triple traverse on 13 or 14 March 1973. One of my closeup maps shows that location with visible tracks around a crater. The crater is visible in this image. Across the crater are the day 2 tracks made on 19 February. My image here is a reprojection to show the tracks better. #moon #luna21 #lunokhod2

Their conclusion: the lunar daytime sky is too bright for useful astronomy. Night would be OK. This is attributed to dust lofted electrostatically or by impacts, and scattering sunlight.

This might seem counterintuitive. Surveyor and Apollo observations show some apparent effects of dust but the LADEE orbiter did not find much. Maybe the new Firefly images will help. Was there contamination of the Lunokhod instrument? We don't know.
#moon #luna21 #lunokhod2

While we are talking about puzzles, here's another. At points marked 'S' on the maps a measurement of sky brightness was reported. Here's the citation:

Severny, A. B et al., 1975. The measurements of sky brightness on Lunokhod-2. The Moon v. 14, pp. 123-128.

They measured in visible and UV, both day and night. The UV sky was a bit brighter than expected, but the visible light sky was 'off-scale' bright and still quite bright after sunset...

Here is another look at the parked Lunokhod 2 rover, a slide from the presentation I linked to earlier in this thread. It shows the assumed orientation of the rover, though it's a bit of a puzzle still. I talked to the laser team, who are having trouble understanding how they get any reflection at all from the reflector in that orientation - it is part of the instrument section at the front (right end) of the rover. #moon #luna21 #lunokhod2

These are the final close-ups of this sequence of Lunokhod 2 maps. At left, a complex bit of driving along the edge of the trough. Some of the maneuvers may be for making stereoscopic pairs of panoramas showing the opposite side of the trough. At right, the last drive and final rover position. It seems the end was sudden and did not leave time for the laser reflector to be pointed at Earth. Its reflections are very weak. #maps #moon #luna21 #lunokhod2

And 2 more maps like this. Here we see the third night location and the place where the rover arrived at the edge of Straight Rille, the long north-south trough.

We will have two more maps like these tomorrow.

Here are two detailed maps of small parts of the Lunokhod 2 drive, this time from the 2nd lunar day, with the cross-shaped magnetic experiment tracks early in lunar day 3. The actual night position is a bit uncertain. It's great to have these wonderful images now, but the quest for something better never ends. Now it's 'we need 5 cm resolution to see details of the lander'. Oh, yes - and for geology.
#maps #moon #luna21 #lunokhod2

And that would not be so bad except that they had to promote it as 'our prof found a rover that had been lost for decades'. Suddenly this was picked up by other media and everyone knew about it. Obviously, VERY quickly, the correct story emerged and I had to deal with it. The next time I saw Sasha Basilevsky I apologised profusely, but he was very polite and forgiving about it. Memo to self - don't be stupid.

Tomorrow: back to reality.

So this particular image got cropped, but rather catastrophically I cropped off the actual rover. Luckily nobody noticed... until I spotted that dark marking and thought it might be the rover. I made this image. You can see the tracks, but in this view you can't really see the extra branch of the tracks running further east and north. I showed a few people, and the next thing I new it was being promoted by our university PR people.
#moon #luna21 #lunokhod2

Where did I barge into this story? We have to go back to March 2010. LRO has begun releasing images of landed spacecraft on the Moon. Remember the map I showed earlier, an old map of the Lunokhod 2 route with LRO images showing that the rover ended further north than previously thought. Now - these LRO Narrow Angle Camera images are big - 5000 by 50,000 pixels, and at the time my software was limited to 30,000 pixels so I always cropped images.
#moon #luna21 #lunokhod2

... They stop and turn around (making the dark spot) to find a way past A and B. The other crater looks like it should be easy to see but it's down-sun and was not noticed. Also they are only using their driving TV cameras - there are no panoramas here to guide us. So they find themselves in the crater and struggle to get out. They have done it before, it should be OK, but the lid hits the crater wall and the damage is done. They get out and stop somewhere nearby.

For years I assumed the dark spot was made by the rover wheels after leaving the crater, but that doesn't make sense. The crater was not seen, and the only way it would not be seen is if the rover is driving away from the sun (Apollo astronauts told us that). The accident happened in the late afternoon when the sun was in the southwest, so the rover was moving northeast. I think the rover was driving north and the drivers saw craters I call A and B on my map ...
#moon #luna21 #lunokhod2

How should we interpret these images? At left I use two images with similar lighting, merged to reduce noise and improve visibility of tracks. In the middle, two images with roughly opposite lighting (morning and afternoon) are merged to reduce the visibility of topography and emphasize albedo (i.e. tracks). They look similar which is encouraging. At right is my interpretation of events. We know they accidentally drove into a crater without seeing it. But how? #maps #moon #luna21 #lunokhod2

This story is all about what happened to Lunokhod 2 on the floor of that crater Ninochka on the previous map. First we will look at what really happened, and we will get to the stupid bit later. Here are 5 different LRO NAC images of the location, chosen to have the best resolution available and different illumination. See how variable the track visibility is. We see tracks, craters and a prominent dark spot (though not prominent in every image)
#moon #luna21 #lunokhod2

There is some uncertainty about the exact position of the 4th night stop, and I may be revising this map later. On day 5 the rover drove further north again before overheating and stopping. The rover activities in this area were instrumental in setting me up for yet another clumsy mistake which got widespread attention. Oh yes, even LRO was not enough to stop me causing chaos... but more on that tomorrow.

Finally we reach the last section of the Lunokhod 2 traverse map. The rover was driven northwards along the edge of the trough, pausing to do a magnetic back-and-forth experiment roughly symmetrical to the one on the other side. At the top of the main map Lunokhod 2 entered the very shallow Ninochka crater, and accidentally entered a small crater inside it. This is where the infamous 'dirt on the lid' event happened, and we will explore it in more detail later. #maps #moon #luna21 #lunokhod2

We are nearing the end of Lunokhod 2's traverse. In this 11th map of the set the rover drives south down the western edge of the trough, eastwards around its southern end, and back to the north again, all in a couple of days. At top right a bit of a second magnetometer excursion is visible, but we will see it all in the next map. In several places the rover stops at a small crater and backs away to bypass it. #maps #moon #luna21 #lunokhod2

Early in lunar day 4 Lunokhod 2 made a drive to the southwest through a shallow 400 m crater called Liya, and then arrived at the edge of a linear trough called Straight Rille. A 'rille' is a valley, a German term from the 19th Century when German astronomers were the world's foremost lunar cartographers. This was the site of another magnetic experiment, not around a crater this time but roughly perpendicular to the rille.
#moon #luna21 #lunokhod2

This is the 9th part of my Lunokhod 2 map. Sorry it's so broken up! - it is designed to fit on pages of a book or PDF document. The rover starts by driving southeast along the base of a hill (Near Cape), then turns north and continues northeast away from the hills. It drives through a crater called Nataliya, shallow enough that it is not much of an impediment to progress.