I think one of the best proofs of the astronauts being on the Moon is the parabolic trajectory of the dust coming off the rover tires

Or off the astronauts' feet, or in a number of other cases. Even those who don't understand the physics of how air and gravity cause particulates to behave can see that there's something "different" about it. And of course those who appreciate physics see exactly what they'd expect to see.

Even 2001 couldn't, as has been pointed out elsewhere.

Kubrick's movie failed to do a lot of things well, despite its enormous budget and the expertise of Douglas Trumbull. And Kubrick insisted on things like visible starfields moving behind the spacecraft. A valiant effort at realism, granted, but you just can't get away from how particulates behave in a vacuum. Unless you're actually shooting in a vacuum you won't get the right effect.

I don't understand the mechanics behind the argument that the clumping visible in the Grand Prix footage is due to interaction with the atmosphere. Usually the presence of a fluid medium impedes the collinear flow of a collection of objects through it. The trajectory of each dust particle through air depends on the precise aerodynamic conditions surrounding each particle, which of course vary greatly between individual particles. Therefore a flock of particles on initially identical trajectories will tend to diverge over time, not clump together.

I presume the hoax believers argue that the flow of dust should be a uniform "rooster tail" which does not congregate in any way. This expectation would be valid if the rover were constrained to operate smoothly over level, unvaried terrain in a constant state of power-skidding.

The so-called Grand Prix was designed to test the capabilities of the rover under extremes of operation -- speed, cornering, etc. Under normal operation very little wheel slippage was observed, evidenced by neatly formed rover tracks in various images.

The irregularities in the surface caused the rover to bounce and the wheels to periodically lose contact with the surface. This would naturally cause them to overspeed, and we expect that when they regained contact with the surface they would slip against it and throw dust.

Recall that lunar soil is highly cohesive, especially when compacted. Thus the impact of the rover wheel will compress the soil into a cohesive aggregate which will behave mechanically as a semi-solid. This explains why the wheel will throw a patch of soil on nearly identical trajectories. After passing out from under the wheel the external mechanical compression force is removed and each particle is free to pursue its own ballistic trajectory.

The clumping is due to the mechanical effects of simultaneous compression and ejection from under the wheel. As John will no doubt witness, this can be observed in earthbound particulates.

The other common argument is that the thrown dust seems to stop a short distance behind the rover, as if it had encountered resistance. The expectation is that it would move horizontally at a continuous high speed which would be easily visible on film. The constant horizontal speed is indeed confirmed by Newtonian physics, but the exact speed at which it moves is determined by its angle of departure from the wheel. The dust we see thrown from the wheels is thrown more upward than horizontally, therefore the horizontal component of the motion is rather negligible. The aggregations of dust that appear to "hang" in the "air" do so because they were thrown chiefly upward, not backward.

I tend to agree with John that photographing the Grand Prix in air would raise a cloud of dust. It's very common to see clouds of aerosolized dust affected by the confluence of the slipstream behind even slow-moving vehicles. The absence of such clouds would quite strongly suggest the absence of a slipstream.