If they look carefully, they will discover that some of their images show the slightest sign of an inversion at the entrance to deep valleys. Mars has the deepest valleys, much deeper than Earth. Temperature rises at 2.7 degrees per thousand feet as you drop down through any atmosphere. A 10,000 foot deep valley will be 27 degrees warmer at the bottom than the surface. Add to that adiabatic temperature effects on the sun-ward side of the valley, (just like we find on the sides of a mountain), will drive a circulation of the warmer air towards that opening at the surface. That in turn creates the visible inversion we see in the images.

Take a look at 195-170505-0449-6-3D-01-Coprates_H and again, 195-170505-0449-6-3D-01-Coprates_L and look at the large valley in the background. I am convinced that what we can see is an inversion caused by moist air making contact with the much drier and colder surface atmosphere.

If that is correct then we have a very real chance of finding moisture and thus life at the bottom, or, on the sun-ward slopes.

I am sure they can drop into the deepest valley possible. In my humble opinion, they must do so.