I think he's just commenting on the wheels, not the mission as a whole. We obviously are good at making wheels that last longer than 10 miles here on Earth.

Agreed but I would call the landing anything but hard. The precision and care with which that vehicle was delivered to the surface is just a mind boggling feature of engineering.

For anyone who missed this, they lowered the rover to the surface from a levitating rocket-powered skycrane.

...which was controlled autonomously to boot!

Definitely one of the most bad-assed ways to deliver a rover to the surface of another planet. If you had told me as a kid this would be possible, I would have considered it almost impossible, except maybe as a science fiction concept.

I don't know if there's another true sentence from which I can derive as much joy as this one.

I'm curious(and this is in no way meant to belittle the work they've done) - if you drove a normal Earth car on the surface of Mars, how would the wheels and tyres behave in Martian conditions? Obviously we have off-road tyres here on Earth which can withstand some extreme abuse, so I'm just wondering - is Martian soil just full of sharp objects? Or is something else going on here?

It does have sharp objects, but ordinary truck balloon tires would handle those relatively well. But at night, the temperatures drop to -100 °C, and your rubber tires freeze and shatter.

Also, rubber's much heavier, and they just couldn't bring that weight. They really couldn't drop that weight from the sky crane, not without increasing the shock absorbers in the legs... which would have meant more weight, and the plan's just impossible.

It also has horrifically abrasive dust, much worse than anyplace on earth. The abrasion from that would wreck a balloon tire seal---hard to predict how quickly.

A balloon tire also goes from "fine" to "useless" with one puncture. Apparently they got surprised by the sharp rocks: http://www.planetary.org/blogs/emily-lakdawalla/2014/0819063... , not having seen anything like that from previous missions.

Well, the tyre will almost instantly go soft as the inflating gas reduces in volume due to the cold. Then the tyre will go flat as the gas escapes (try driving for a couple of years without pumping your car tyres up). And the rubber will freeze and crack, and get UV perishment and low-pressure outgassing of its own.

The balloon-like tyre of choice is a springy basket mesh, as seen on the Lunar rover. But that's only needed because we wanted to drive around at human-acceptable speeds (to get to interesting places before the humans had to go home). With a teleoperated robot, we can take our time, and that means we don't need bouncy suspension. Which is good, because big wire tyres are quite heavy.

That is the best solution for Mars, but you might need to build the rover in a freezer. Tires that would be soft at Mars temperatures would be liquid or worse at Earth temperatures. For example, you might fill a normal tire mold with diesel, then cool it with liquid nitrogen and there you go -- a lovely tire for Mars that will melt at normal Earth temperatures.

You'd still want to go airless probably, due to a lack of repair shops.

I think low temperatures alone would wreck Earth tires (and the rest of the car, but that's a different story).

Well, regardless of how well an Earth car would perform, it'd likely be far too heavy/expensive to get to Mars in the first place. It's impressive how NASA can solve problems with the resource constraints they have.

It would obviously be a dumb idea, but Curiosity is in the same ballpark as a car in both size and weight (1,982 lbs). A Smart Car is ~1,800 pounds, so it's actually heavier than some Earth cars!

Interesting, I didn't know that Curiosity was that heavy! It's a ways away from Jeep Wrangler/military Humvee territory (especially if you loaded one of those up with the required scientific instruments) but it'd be cool to see NASA go with something heavier-duty for longer-range missions in the future.

Is the terrain any more dangerous or grueling than a desert terrain on earth though?

From my laymen perspective I'd say the terrain itself is less of a problem, the change in temperatures is much more extreme. This article from 2014 has many insights into prior Curiosity wheel damage:

http://www.planetary.org/blogs/emily-lakdawalla/2014/0819063...

This is a great article. Thanks for the link.

One thing it points out is that the rocks in that particular part of Mars are special: they are sharp and cemented into the terrain. There are places on Earth that have this kind of rock, but they are unusual. The wheels do fine in a rocks-in-sand scenario.

The article goes into a lot of detail, and it turns out that some of the obvious armchair science explanations for what is happening are not the case. For instance, the main constraint on the mass of the wheels was not keeping the liftoff mass of the payload under some limit.

Sharper rocks than a lot of Earth deserts - less wind and no water to smooth things down.

More broadly, though, there are some deserts on Earth that are pretty hair-raising. The NPS guidelines for driving deep in the Canyonlands (on roads, no less) warns that with a high-clearance 4WD pickup, you should still expect "considerable risk of vehicle damage". Curiosity is going a lot slower, but it doesn't have the luxury of roads or anyone to toss on a spare tire.

Depends on which trail in Canyonlands. Some of those are extremely technical crawl trails where you need a spotter and are planning every ten feet of movement, not unlike the Rubicon. White Rim is more of what I would call a road; watching a couple videos of people running it, I'd be less worried about damage there. (It's on my list for this spring.)

Honestly Jeep owners read a warning like that and get excited. Every scar in my paint is a new story, but to your point, getting the tools out in the backcountry is usually not fun.

Yeah, fair. I was specifically quoting the warnings for the Maze, which is remote enough that they desperately want to avoid tows and rescues.

I'd love to do White Rim whenever I get a chance, the overlooks onto it make it look wonderful. The Maze stuff looks much less friendly, but it's on the 'someday' list.

Oh, sure. The Maze was the area I was thinking of as well. I have a few thousand dollars of work and a lot more practice before I could comfortably consider those trails. I know my limits and I'd rather not hike out of Utah.

They drive it over desert-like terrains now to avoid such problems, but AFAIK the very first hole punched to one of the wheels was due to a small pointy rock. Martians rocks suck.

This is not obvious from the perspective of someone who's not familiar with rocketry or how light space structures need to be.