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Mashable.com's Every rover, ranked by distance traveled on the moon and Mars; The 13 rovers, ranked. calls attention to this amazing feat, and a review of basic statistics and discussions on odometry are available.

Driving this far requires careful navigation, avoiding crashing into things, getting hung up, stuck in "sand traps" or falling into holes. You need a good safe stretch of luna firma and some luck, but also plenty of data and careful attention and risk management.

You've also got to have every critical bit survive the cold lunar nights and be able to soak up and use plenty of solar power during the day to drive those 1970's motors and wheels across rough terrain. Certainly the low lunar gravity helped here.

And the four months is really two months because of the lunar night.

Question: How (the heck) did Lunokhod 2 drive, navigate and survive a ~40 kilometer drive over four months on the Moon using 1970's technology?

All Mars and lunar rovers ranked by how far they've driven. Credit: Bob Al-Greene / Mashable

All Mars and lunar rovers ranked by how far they've driven. Credit: Bob Al-Greene / Mashable

Sources of data: NASA, JPL-Caltech, GSFC, Arizona State University, China National Space Administration

uhoh
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    What sort of answer are you looking for here? As written, the question is very broad. – Russell Borogove Aug 16 '21 at 03:07
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    @RussellBorogove 1970's technology (motors, batteries, video cameras, radios) may have been intrinsically more robust than current technology against the lunar environment thermal, radiation, etc) in some ways, but much less than other ways. Without a navigation computer driving live(?) almost a kilometer a day via radio must have been really challenging. Seems like a miracle to me! So an answer that addresses those specific challenges via an outline + links seems best. It wouldn't have to be very lengthy itself, but it requires someone with some knowledge and understanding to do it. – uhoh Aug 16 '21 at 03:13
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    @RussellBorogove Perhaps I should break this up into separate questions? It seems that "How did they drive, and from where?" might be a really interesting question all by itself now that I think about it. – uhoh Aug 16 '21 at 03:15
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    @RussellBorogove I don't think this question is overly broad – Ingolifs Aug 16 '21 at 04:09
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    Possibly the main reason Lunokhod could range so fast is because of the signal delay between the earth and the moon, which is a 2.6 second round trip. Growing up playing quake in the 90's in new zealand, I can confirm that this feedback delay, while unplayable normally, is still sufficient to move around relatively easily. Mars has a signal round trip of between 8 and 48 minutes. Navigation therefore proceeds at a crawling pace. – Ingolifs Aug 16 '21 at 04:30
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    Maybe the Soviet Union had excellent engineers? – Patrick Aug 16 '21 at 12:10
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    The same way the Apollo 17 LRV did? Most of these distances are the distance the vehicle did travel, not the distance it could have travelled. You're making the Lunokhod 2 sound like some unique rover whose performance was far beyond anything that came before it and was impossible to match for 40 years. – chepner Aug 16 '21 at 13:31
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    @chepner The Apollo LRVs had the advantage of a human driver (and passenger), directly controlling them without any transmission lag, and maintaining/repairing them on site. Not only would they be better at avoiding obstacles, but if it gets stuck in a ditch (which actually happened in at least one case), the two astronauts aboard could get off, assess the situation, and extract it to get it up and running again. This is a bit harder with a remotely controlled vehicle. – Darrel Hoffman Aug 16 '21 at 13:50
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    @dlchambers Yes, sure, the country that sent the first satellite and the first person to space did so using stone age tools. It is true that in some areas the Soviet Union was behind the west (microelectronics), but in others it was ahead (metallurgy). If you believe the Soviet Union had the technological level of 1850's Russia you're mistaken. – Patrick Aug 16 '21 at 13:50
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    Another aspect: Spirit and Opportunity were both lost by problems resulting from dust blocking their solar panels. You don't have that problem on the moon. Also a lot more solar energy per area on the lunar surface than on Mars. – KarlKastor Aug 16 '21 at 17:38
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    I think the real question that is bothering you is "why is nobody repeating the feat". And the answer is same as always: we (the humanity) are not doing it not because we can't but because nobody is willing to pay for it anymore. – Agent_L Aug 16 '21 at 18:09
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    @KarlKastor That's a bold statement considering one of Lunokhods was lost due to dust : ) – Agent_L Aug 16 '21 at 18:09
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    Does the mileage shown for Apollo 16 also include John Young's Grand Prix? – DrSheldon Aug 16 '21 at 19:29
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    @Patrick That was a Star Trek TOS reference. Sorry if it was too obscure. – dlchambers Aug 17 '21 at 14:13
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    It looks like it has more wheels than the other rovers. – TylerH Aug 17 '21 at 15:21
  • From an automotive point of view, surviving 4 months/40km without a service isn't exactly groundbreaking. – SE - stop firing the good guys Aug 18 '21 at 13:08
  • @SE-stopfiringthegoodguys it certainly drove further than Roadster – uhoh Aug 18 '21 at 13:51

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A few interesting videos about the lunokhod rovers:

The chief designer of the lunokhods (Lunokhod 1 & 2) was Aleksandr Kemurdzhian, a tank designer. Being a tank designer his initial designs had the lunokhod use tracks, but research indicated tracks could get stuck in certain situations so the design was changed to eight independently moving wheels. According to Secret Soviet Lunar Rovers and Extra Terrestrial Cars - Lunokhod, the vehicles could move if only three wheels weren't stuck. The development of the lunokhods was very well tested and researched prior to construction and deployment.

To power the craft during the lunar day solar cells on the inside of a lid for the craft were used. During the lunar night, the lid was closed, the internal compartment of the lunokhods was filled with a gas heated by an external polonium-210 source.

The lunokhods had four corner cameras produced high-resolution panoramic images, with a pair of front-mounted TV cameras for the rover’s operators.

Each lunokhod was controlled by a five man team, a driver, commander, navigator, engineer and radio operator – having practiced on a simulated lunar surface.

The sweating driver was guided not by video but a succession of still images, updated every 20 seconds. He had to contend with the 2.5-second signal delay, as well as a metre-wide blind spot ahead. Lunokhod 1 had two speeds: 0.8 km/h or 2km/h, plus reverse gear. Drivers recalled details from previous images to manoeuvre safely and were dependent on shadows to make out surface relief. They did not drive during the three days of lunar noon, or when the Sun was low in the sky. Each lunar night they left the rover to hibernate.

From ROBOTIC AND MANNED LUNAR ROVERS OF THE XX CENTURY: THE VIEW FROM THE XXI CENTURY

The accumulated experience of the crew resulted in an increased duration of typical non-stop driving time from 50 s for Lunokhod-1 to 350 s for Lunokhod-2.

The remote control drivers were located at Simferopol in Crimea.

The design of the lunokhods was robust enough for even longer missions but the demise of Lunokhod 1 was the exhaustion of polonium-210. Lunokhod 2 failed due to overheating after it was accidentally driven into a crater the drivers didn't notice. Lunokhod 2 was simply driven through the crater which, unknowingly, had soft walls which covered part of Lunokhod 2 with dust. When then lid was open the dust was deposited on thermal exchange unit and Lunokhod 2 stopped functioning shortly afterwards.

As a side note, Aleksandr Kemurdzhian designed rovers for the clean up of Chernobyl, after the ones obtained from the then East Germany failed to operate as anticipated.

muru
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