I was going to ask what the primary reason is that Curiosity is so slow... is that on-topic here?
(If not, any ideas if any SE site is suitable for it?)
Questions related to the maintenance and repair of motor vehicles and their accessories, internal combustion engines, even in applications other than automotive so long as the question is related to engine or engine accessories
The Mars rover has nothing to do with the repair of motor vehicles.
Seen as a question on experimental design this comes pretty close to being suitable for Physics.SE (where I am a moderator).
However, the focus would have to be on how the mission constraints and requirements led to a low speed (and I think the answer may be "because it doesn't need to be fast", frankly).
Some related questions, which may also supply some tagging suggestions.