> After running thousands of simulations, the team raised the rover’s tilt limit to 24 degrees and reduced the clearance required under the rover’s belly pan to 20 centimeters (about 7.9 inches). The team also updated the rover’s braking software to avoid rock hazards, nearly doubled steer motor current limits, updated flight software with “dynamic slip tables” to model expected slip, and used cross-slope driving to better anchor wheels on exposed bedrock.

I wonder why they didn't model and use these parameters in the original design (I'm not at all suggesting a mistake on their part; I wonder what their thinking has been):

Were Martian environmental parameters less well-known (e.g., how gravity, air resistance / wind, and scree dynamics interact)? Bot performance in Martian environment (e.g., motor power output) less well-known? Were they being understandably conservative with their irreplaceable bot?

> Were Martian environmental parameters less well-known (e.g., how gravity, air resistance / wind, and scree dynamics interact)? Bot performance in Martian environment (e.g., motor power output) less well-known? Were they being understandably conservative with their irreplaceable bot?

I haven't worked on the Mars rover programs, but I have worked on a NASA moon rover. Based on that experience I would hazard a guess that it's all three of these things.

Environment: We actually have quite a bit more experience roving on Mars so I expect the environmental uncertainty is a bit attenuated for the Mars missions, but one thing I was really surprised by during my time on the moon rover mission was just how little confidence our scientists had about the physical conditions at the specific landing site we are targeting (which is quite far from the Apollo missions for example)

Performance: Building accurate hardware tests on Earth for operations on another planetary body is incredibly hard. Of course NASA engineers are smart and can do this with fairly high confidence, but it's far from perfect. For the moon's 1/6th gravity, we couldn't just build a copy of the moon rover and test it on Earth because the suspension would collapse, so we had a whole separate copy of the moon rover mobility and suspension that was built to operate in Earth gravity yet mimic the performance the actual rover would have on the moon. That unit in and of itself is a feat of engineering that is definitely not immune to mistakes.

I assume everything was very conservative and safe back during initial design.

Now they have a ton a data and a long unimaginably successful mission they can take a few more risks.