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I found the following to be interesting. It appears that for the most part (Apollo 15, 16 and maybe parts of 17?) there were restrictions placed on the distance allowed for the LRV to travel. The astronauts should be able to walk back to the LM should the vehicle for any reason break down, which seems reasonable, it seems outrageous to bet your life that this car will not break down.

From Wikipedia (the "Lunar Roving Vehicle" article):

An operational constraint on the use of the LRV was that the astronauts must be able to walk back to the LM if the LRV were to fail at any time during the EVA (called the "Walkback Limit"). Thus, the traverses were limited in the distance they could go at the start and at any time later in the EVA. Therefore, they went to the farthest point away from the LM and worked their way back to it so that, as the life support consumables were depleted, their remaining walk back distance was equally diminished. This constraint was relaxed during the longest traverse on Apollo 17, based on the demonstrated reliability of the LRV and spacesuits on previous missions. A paper by Burkhalter and Sharp provides details on usage.*

My question is, when the restriction was lifted, how far away was the furthest distance from the LM that was achieved? Not total distance driven on one EVA, but longest distance in a straight line from the rover to the LM.

Is there a picture of this record? I'd love to see it.

As an aside (but closely related): How reliable was really this vehicle? Is the Wikipedia statement accurate, that the vehicle was "so reliable" that they lifted this restriction?

I have found that the LRV apparently has redundancy in its power system (two batteries) and redundancy in its steering system (front and back can be steered, and one system can be disconnected independently of the other).

However this note from EVA-3 on Apollo 17 seems to suggest the LRV was not perfect:

"169:18:27 Cernan: I'm reading 80 on the amps, 78 on the amps...Correction, that's amp-hours. Voltages, 62 and 65. Battery 1 (temperature) is 132, forget 0. Motor temps are 200 and 210 on the rear, 200 and 250 on the forward.

[The battery 2 temperature gauge has malfunctioned, hence Gene's "forget 0".]

[Gene and Jack have driven a total of 36.0 kilometers and have used 57.2 amp-hours -plus another 14.8 amp-hours for LCRU operations - out of the 242 amp-hours available. Their average use rate of 1.58 amp-hours/km is similar to the 1.67 am-hours/km used on Apollo 15. The use rate on Apollo 16 was nearly twice as much due to an unexplained malfunction.]"

*Burkhalter, Bettye B; Sharpe, Mitchell R (1995). "Lunar Roving Vehicle: Historical Origins, Development and Deployment". Journal of the British Interplanetary Society 48 (5): 199–212.

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    $\begingroup$ I believe (but don't have time to find references hence not an answer) that the original constraint was to account for failures in both the LRV and the EMU, i.e. the astronauts must be able to walk back with one PLSS failed using the buddy system or OPS. With the relaxed constraint on 17, they could still walk back if the rover died but they would need both spacesuits to continue operating. Or vice versa - they could tolerate a spacesuit failure if the rover kept going, since the drive time was less than buddy and/or OPS endurance. $\endgroup$
    – pericynthion
    Mar 15, 2015 at 6:15
  • $\begingroup$ What are the units for those temperature numbers? $\endgroup$
    – pjc50
    Dec 23, 2015 at 11:20
  • $\begingroup$ @pjc50 degrees Fahrenheit. $\endgroup$
    – hobbs
    Jul 10, 2016 at 20:03

2 Answers 2

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According to Google Earth's map of Apollo 17 on the Moon, 7.41 km, or 4.6 miles.

enter image description here

If you want to look at the map, open Google Earth, and in the menu bar at top click on View > Explore > Moon. All of the Apollo missions are indicated by a little astronaut icon on the place where they landed, holding a little flag with the number of the mission. Make sure the 'Moon Gallery' box is checked in the Layers section on the bottom left.

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  • $\begingroup$ This doesn't fully answer the question. On earth, breathing the atmosphere, without a spacesuit, I can walk 4.6 miles without major issues. In actual conditions, how far could they have walked back? 4.5 miles? 2 miles? $\endgroup$
    – raptortech97
    Mar 15, 2015 at 3:39
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    $\begingroup$ It was the part of the question i could answer. $\endgroup$
    – kim holder
    Mar 15, 2015 at 4:21
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For whatever reasons and before the Apollo 16 flight, NASA had already made a rule limiting the farthest distance that the rover could be from the LM, to five miles. Apollo 16 astronauts tried to persuade NASA that should the rover break down, they could get back to the LM from a distance of 10 miles, and demonstrated the fact on earth at a NASA facility by jogging 10 miles in simulated one-sixth gravity and wearing their space suits. NASA wouldn't budge.

(Duke, C. & D., Moonwalker. Thomas Nelson Publishers, Nashville, Tennessee. 1990. pp.148-149)

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