[dtengineering]

As much as I agree with the statement that "in the simplified theory of friction as taught in high school physics class, extra wheels should not increase traction", it is important to remember that the simple relationship between normal force and resultant force makes some assumptions that may or may not hold true in a practical environment.

For instance Formula One race cars evidently find that having a larger contact patch improves traction. This does not contradict the theory taught in high school physics, but does mean that some of the assumptions made in that theory are not valid in the race track environment.

For instance the "high school" theory assumes that neither surface deforms due to the normal force (remember that the regolith lies over top of carpet, and is a fairly thin material...), nor fails under the resultant force. Given the "white powder" produced by spinning wheels as reported on CD, there is definite surface failure during dynamic friction of highly loaded wheels. Perhaps this is less of an issue with lightly loaded wheels....

Perhaps they are on to something with this design, perhaps not. I suspect not, but if the team has tested multiple wheels and found them to be an improvement then they have my congratulations for not being bound by the assumptions of a simplfied theory.