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I just finished reading "A Man on the Moon" by Andrew Chaikin, an amazing read. For the missions involving the Lunar Roving Vehicle (LRV, Apollo 15-17), there are some mentions of astronauts reporting on the traversability of the terrain and how it compared with predictions from mission planners: more (small) craters than expected, less boulders, etc.

Were there backup traverses planned for these missions? For instance, if one or a few waypoints/stations could not be reached due to undrivable terrain, were there other/alternate routes prepared? And if so, are they documented anywhere?

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    $\begingroup$ Apollo 17 Traverse Planning Data, 3rd Edition states "In order to expedite publication of the changes to the nominal traverses, the contingency planning summary will be issued in a special supplement." Unfortunately I haven't been able to locate the supplement. $\endgroup$ Oct 8, 2021 at 18:23
  • $\begingroup$ Interesting, I'll look out for that! I wonder if a similar contingency plan was issued for earlier missions, or whether this only happened on Apollo 17 in response to events on Apollo 15 or 16. $\endgroup$
    – olamarre
    Oct 8, 2021 at 20:00

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There were no back-up routes. Basically, they went along as they saw fit.

You can find the mission rules on the Apollo Lunar Surface Journal. Unfortunately, only the one for Apollo 16 is complete with the mission rules for the LRV excursions (section 31), but presumably those for Apollo 15 and 17 are similar. Rule 31-1 is reproduced here:

Mission rule 31-1 for Apollo 16

LRV mobility rates will be determined in real time. These rates will be projected for maintaining the effective operational envelope and reassessing the traverse plan. The projected rates may be adjusted upward or downward from computed rates based on the qualitative judgement of:
A. Terrain differences
B. Losses in driving time attributable to surface observations
C. Unscheduled stops

Rule 31-31 and 31-32 establish the priorities for the EVA, and rule 31-33 made sure that those priorities were evaluated against (among others) the operational state of the LRV and the condition of the terrain:

Mission rule 31-33 for Apollo 16

Reassessment of the operational EVA plan will be done if any of the following conditions exists:
A. Behind timeline by more than 10 percent of EVA time remaining
B. Ahead of timeline by more than 15 minutes
C. Degradation of the LRV to such an extent that a minimum of 4 km/hr vehicle speed cannot be maintained or the planned traverse violates the redefined operational envelope

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  • $\begingroup$ Wow thank you so much! This is awesome. As Organic Marble pointed out in a comment on my question, in Apollo 17 Traverse Planning Data, 3rd Edition, it mentions "In order to expedite publication of the changes to the nominal traverses, the contingency planning summary will be issued in a special supplement.". Perhaps contingency planning sort of refers to using the same rules as Apollo 16 as you shared above? They drove a lot during Apollo 17, I wonder if their rules were different. $\endgroup$
    – olamarre
    Oct 2, 2022 at 15:43

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