With the difficulties of driving Lunokhod 1, Lunokhod 2 had improvements: the camera used for driving was mounted higher, to give a better field of view and the camera frame rate was 3 seconds compared to 20 seconds for Lunokhod 1.
Despite craters and rilles, the terrain traversed by the lunokhods was relatively flat.
If distances of 16.53 km could be achieved in one day, or even 8.6 km or 3.13 km, this would suggest that despite a limited field of view and driving by "slide show" (continuous still photography) with a refresh rate of 3 seconds driving Lunokhod 2 may not have been very difficult, for the terrain traversed.
Once Lunokhod was on the moon, the success of the mission would be in the hands of two five-man crews chosen from the military’s missile defense corps. In the spring of 1968, candidates were carefully screened for engineering expertise, capacity for prolonged mental focus and attention, quick reaction times, the ability to process information quickly, good long-term and short-term memory, and vision and hearing. So thorough was the selection process that some of the men thought they were being recruited for the cosmonaut corps, until they were told of their real mission: to operate the first wheeled vehicle on the surface of another world.
Only one member of each crew would drive the rover. Behind him would sit the crew commander, who would oversee the driver’s handling of the rover. Joining them in the control room would be a navigator, a radio antenna operator, and the flight engineer, who would monitor the rover’s systems. Each crew would operate the rover for two hours; then the other crew would take control. At the Lavochkin plant the crew members familiarized themselves with every aspect of the craft and spent hours practicing with a mockup on a specially constructed “lunodrome” near the mission’s control center, in the Crimean city of Simferopol.
... Under driver Gabdulkhay Latypov’s control, the rover descended one of the two ramps extended from the descent stage and stood on the moon’s surface, ready to begin its expedition.
Gripping in his right hand a control stick that resembled a car’s gearshift, Latypov could make the rover go forward at one of two speeds (0.5 or 1.2 mph) or go in reverse. He and Vyacheslav Dovgan, the other crew’s driver, turned the craft not by rotating the wheels, which were fixed, but by slowing down one side relative to the other, the way one steers a tank.
Latypov and Dovgan’s only guidance came from a monitor, which displayed images from Lunokhod’s two low-resolution television cameras. To any video game enthusiast it sounds simple—but this was nothing like a video game. The cameras did not send a continuous stream of images, but rather single frames, like a slide show, at intervals that varied from seven to 20 seconds. And because radio signals took three seconds to travel round trip between Earth and the moon, the driver didn’t see the results of his actions for many long moments. For this reason, if crew commanders Nikolai Yeremenko and Igor Fyodorov saw Lunokhod heading toward catastrophe, they could push a button to halt the rover.
Dovgan, now 66, was well prepared by intensive training. “Driving on the moon felt even easier than it was in the lunodrome,” he says, but his comment belies the difficulties of navigating the rover. The low resolution of the slide show made it difficult to spot craters and boulders, especially at high sun angles, and there was a “dead zone”—a three-foot-wide area immediately in front of the rover that Lunokhod’s cameras could not see. The only solution, according to Dogvan, was to memorize the features in this area from the previous image, before the rover reached it. “When we were looking ahead and thinking of the obstacles that we did see, we also had to remember what was just behind,” he says.
Dovgan also had to constantly verbalize what he saw to Fyodorov. “103,” Dovgan would say, using the commander’s call sign, “this is 101 reporting on the situation. Twenty degrees left of the course, a stone; distance, five meters; height, 35 [centimeters], width, 50. Straight ahead, a crater, diameter, nine meters. To the right, 15 degrees, a gap. Decision: Will turn left 60 degrees to avoid both crater and stone, and then regain the straight-ahead direction.” Although Fyodorov sometimes challenged Dovgan before approving his plans, he ultimately trusted his driver’s judgment as if Dovgan were actually on the moon. And indeed, Dovgan sometimes felt as if he were. “Not that I forgot that I was on Earth, but it felt like I was so phased into my work that the only thing that wasn’t part of me being on the moon was the constant, continuous reporting,” he recalls. “It almost felt like I was talking to myself all the time, or that I was talking to Lunokhod.”
... As the controllers gained more experience, they also gained confidence, until they were able to let the rover proceed as long as they could see no clear hazard on the monitors. Progress had to be halted for three days during the lunar noon, when the lack of shadows made driving too dangerous.
... large rocks—were hazards the drivers and commanders wanted to avoid. Having learned (just as the Apollo astronauts had) that distances on the moon are difficult to perceive, and wary of the time delay, Lunokhod rarely ventured closer than about seven feet from a boulder. “They were cautious people,” Basilevsky says about the crews, adding that he never saw them disagree about how to proceed, or any other breach of military discipline
... the crews’ supervisors, who equated the mission’s success with the total distance logged by the rover. The only way to obtain panoramic images with Lunokhod’s high-resolution cameras was to use the craft’s narrow-beam antenna, which required the rover to be stationary. At one point, Basilevsky recalls, “We could see beautiful rock fragments. I was saying to Babakin, ‘Let’s stop here. We’ll make good panoramas; we’ll see something unusual here.’ His deputies told me, ‘Sasha, it is Lunokhod, not Lunostop.’ ”
It was even harder for Basilevsky to use Lunokhod to obtain stereo images, one of the geologists’ key tools for studying lunar landforms. The easiest way was to take a panorama, have the rover turn in place for a few degrees, then stop and take a second panorama. But for the mission managers, taking a second panorama of “the same boring place” precluded the logging of more distance, which looked good in Pravda, the state newspaper. To publicists, “it was a serious indicator of our success: meters, meters, meters,”