I had the afternoon off today, so I popped over to the National Air & Space Museum's Udvar-Hazy Center. I spent some time looking at their Mars Pathfinder display. Their Pathfinder is an engineering duplicate of the lander, and the Sojourner is "a nonworking model built by JPL for the NASM." One thing that struck me was that the ramps for Sojourner looked too narrow. It looks like there are metal guides that are about the same distance apart as the inside wheelbase dimensions, so they could act as a guide for Sojourner's wheels. However, there didn't seem to be enough width of material outboard of those guides on which Sojourner's wheels could safely travel or be supported. The only other thing I can figure is that the dimensions on these two display items don't match up.

Does anyone recall how that worked?

Here's a photo I snapped today, perhaps you can see what I mean.

Sojourner model on Pathfinder

http://mars.jpl.nasa.gov/MPF/ops/80911_full.jpg

From the tracks at the base of the ramp, this looks about the same as the museum display.

Phil

I guess the ramp material is stiffer than it looks!

Found the movie of the roll down the ramp - it does indeed use the metal guides and roll the wheels outside of them - that looked like a tougher steering challenge than I remember!

Sojourner rolls down the ramp

Looking at my image from the museum, it appears that the guide on the right side of the picture extends farther back onto the lander deck than the one on the left. That would have served to align the wheels and drive path as Sojourner first began moving.

http://trs-new.jpl.nasa.gov/dspace/handle/2014/23848 may be of interest.

Super, thanks for the link!