Given the fact that much larger holes were manufactured into the wheels for the JPL Morse tracks, my concern level is zero.

Everything I've heard and read, repeatedly, states it's not a concern.

There were holes in the wheels on the VSTB rover in the Mars Yard long before MSL launched. This shouldn't really be a surprise to anyone.

So why not put this thread to bed.

Group therapy for the morbidly pessimistic.

Pictures of the wheels are great, particularly when a wheel is perched on a rock. That tells us that a particular rock is mechanically strong, unlike some of the poorly consolidated sediments around. There should be a place for posts like that. But I agree: time should be called on endless unfounded worries about the wheels.

I was not talking about the large rectangular Morse Code holes, but the irregular large holes with jagged edges.

http://www.unmannedspaceflight.com/index.p...st&id=31571

It's just surprising, that's all. I don't want to re-hash old stuff. Originally these were dismissed as glints or reflections. I just find it interesting that with 6 wide wheels with such a large contact area and reduced gravity, that one rock would be able to punch a hole in the material.

I won't comment anymore.

We get that, but the other holes show that the ones you asked about don't matter. They can't spread far because of the big cleats. It's interesting to see this but it doesn't matter.

Now let's get back to looking at the stuff you can see through the holes: Mars.

Phil

Why not use tires made of a titanium alloy?

Because they would weigh more and be less compliant; the wheels are basically the only shock absorbers in the system.

I have to say I feel a bit conflicted about this thread. On the one hand, some posts seem to be armchair engineering suggesting that there's something wrong with the system. On the other, some are just mostly-baseless cheerleading. I've tried to stay in between those two places by talking about the real engineering to the extent that I can, but maybe we've reached the point of diminishing returns on this topic.

I agree with the above sentiment, and with mcaplinger and others - surely this thread beat itself to death back in the summer?

If the wheels all completely fall to bits, and the rover takes an undignified nosedive into a pothole as a result, then people should feel fully justified in lambasting those who assured us that the wheels were up to the wear-and-tear.

Meantime.....

I think that it's safe to say that the admin/mod team has decided to keep this thread open since over time more holes will appear, and hopefully it will function as a place for people to find answers (esp. those new to UMSF), which have been graciously provided by members such as mcaplinger.

However, alarmism will not be viewed favorably, nor will criticism of the project team or designers.

Engineering is all about compromise. We could have had massive wheels impervious in all respects to anything, but probably would have had to lose one or more instruments, and/or change something in the EDL methodology, and/or, and/or...it tends to snowball.

The wheel design is highly robust & survivable, and it's the best compromise that could be derived based on overall system performance requirements.

Enough said.

I am only asking questions to learn about the engineering design process and considered wheel options – unfortunately so far with little success.

Nobody's preventing you from doing so; again, that's what this thread is for.

My comments were not directed at anyone in particular; just wanted to define some boundaries.

These stereo views seemed to go better in this thread than anywhere else. The slight axial tilt of the camera during the MAHLI surveys allows for a reasonably robust stereo image of the center wheels on either side. Here are a few recent views (with brightness levels bumped in a few to bring out some detail in the shadows) ...

...from Sol 476:




...and from Sol 472:




(..and not to beat a dead topic, I personally think the wheels will be just fine even with a great number of holes - they have huge built in "JPL" holes - so it's hard to imagine enough damage to seriously impact the rover's mobility...)

A quick google search unearthed the following: 80+ pages of informed insight into the next generation (in which MSL is referenced) of rover wheels, and the engineering challenges/trade-offs faced by the terrain they would be exposed to. Admittedly the article references largely re-configurable wheels, but some of the challenges faced and the outcomes settled upon are instructive.

enjoy!