Updates Mars Science Laboratory (Curiosity)

[MattBaker]

for the 2020 mission so the rover can last through its prime mission?

AFAIR that rover is still in the design phase, they don't even know which instruments will be on it and what purpose it should fulfill, sounds like plenty of time left to learn from Curiosity mishaps.

 

[Ripley]

Ok, I can understand that in order to reduce the overall weight engineers cut holes where they can, use special alloys, tend to lighten everything up...
I can understand that the "wheels" cannot be 100% rigid and they must work as shock absorbers...

But such an extensive damage after such a short time! Looks like some shrapnel damage, as if something impacted with the wheel at high velocity, but we know Curiosity drives around quite slowly.

Is it just too heavy for its wheels to properly sustain it?
Can radiation be blamed for "softening" the wheels somehow?

 

[Keatah]

Radiation is not an issue here. It's simple matter of rolling over one large rock, and having the force concentrated in one area. A simple puncture.

Just take a screwdriver to a soda pop can and conduct your own experiments. The wheels aren't that much thicker.

---------- Post added at 04:37 PM ---------- Previous post was at 04:24 PM ----------

The highest impact velocity would be if a wheel was "precariously balanced", slipped, and fell down on to a sharp pointed rock. Depending on how far the wheel fell would of course determine the speed and impact force.

You could calculate the instantaneous impact force. You know Mars' gravity, the weight of the rover, and how far it might "fallen" or slipped.

Maybe a rock was supporting the rover, cracked and gave way, and CRASH! The rover wheel drops 5cm and onto a spiked outcropping. Or maybe it tried climbing onto that same spike. It wold be the equivalent of running over a nail.

 

[Ripley]

So it's just an unbelievable, shortsighted, prosaic miscalculation (human error) of load/resistance made at project stage?
I can't believe that! :shrug:

Maybe a few more millimeters of thickness could have avoided this.

Ok, that's rocket science and it's not an easy task, dV, weight...all that.
It's just too early to "fall apart".

 

[statickid]

Especially with the rtg, it's just too awesome. Looks like we'll all see if curiosity can really be keep crawling on stumps like they claimed. Worst case scenario, it can be a stationary weather lab. There was a time when landers had to do all the science in one spot

---------- Post added at 07:14 PM ---------- Previous post was at 07:03 PM ----------

It may also be as simple as misjudging the exact character of the terrain a little bit. For example slightly sharper rocks on slightly firmer ground, less sandy than anticipated. OR they were a little bit too cocky with the auto pilot they are showcasing.

 

[Ripley]

...It may also be as simple as misjudging the exact character of the terrain a little bit...

Yes, I also think it must be like that.
My previous post was a bit overpessimistic...

 

[RisingFury]

Let's not forget Curiosity is ~900 kg and the size of a car. Due to its sheer size, it can drive over rocks. MER is only ~190 kg and is so small it needs to avoid rocks that Curiosity can drive over.

 

[barrygolden]

Really would like to see MSL fly in orbiter

 

[Donamy]

Could it have happened on landing ?

 

[MattBaker]

Could it have happened on landing ?

If you're talking about the wheels: No. They are doing dozens of photos every day so they can keep track of the wheels quite well. The landing and the forces acting on the wheels might be a contributing factor there but the landing alone? Nope.

Example picture from Sol 34:

Dusty but no punctures.

 

[Unstung]

 

[N_Molson]

Remains us that Mars surface isn't exactly a gentle highway to drive on at full speed... Seems that the Moon is better, more sandy.

Heavier rovers used for manned exploration would have a hard time going faster than a few kph, I think.

 

[Urwumpe]

Looks like it simply drove over a too pointy rock too much.

 

[MattBaker]

Heavier rovers used for manned exploration would have a hard time going faster than a few kph, I think.

Curiosity's top speed is only 0.09 km/h. Top speed.

 

[Urwumpe]

Curiosity's top speed is only 0.09 km/h. Top speed.

And that for a nuclear rover.

 

[statickid]

how about simply developing a flexible tire :blink:

I know easier said than done, but after this mission, I'd wager to see less metal cast/sheet tires and more woven, composite, or otherwise more flexible tires on future heavy rovers

 

[Unstung]

There's some more news related to the holes. Extra precautions have been added to avoid wheel damage.


JPL: "Curiosity Adds Reverse Driving for Wheel Protection"

On Tuesday, Feb. 18, the rover covered 329 feet (100.3 meters), the mission's first long trek that used reverse driving and its farthest one-day advance of any kind in more than three months.

The reverse drive validated feasibility of a technique developed with testing on Earth to lessen damage to Curiosity's wheels when driving over terrain studded with sharp rocks. However, Tuesday's drive took the rover over more benign ground.

"We wanted to have backwards driving in our validated toolkit because there will be parts of our route that will be more challenging," said Curiosity Project Manager Jim Erickson of NASA's Jet Propulsion Laboratory, Pasadena, Calif.

[...]

The Planetary Society: "Curiosity update, sols 540-8: New rules and longer drives"

Driving backward is also helpful, according to the release. I think it's amusing that all of the Mars rovers have wound up needing to drive backwards. I actually ran across a planning document somewhere that explained that the rocker-bogie suspension system does function marginally better that way -- driving bogie first -- and that the rovers are deliberately built rocker-first so that in case they wind up in a bad situation, they will be pointed in the "better" direction to extract themselves. In any case, the three rovers wound up driving backwards for different reasons: Curiosity to prevent wheel damage; Spirit, because one front wheel had siezed up and had to be dragged behind her like a ball and chain; and Opportunity only drives backwards half the time, to help evenly distribute lubricant in the wheels. Sadly, she was driving backwards when she got embedded at Purgatory -- but that ended well, so it's all good. (UPDATE: A reader reminded me that Opportunity is now driving backwards almost all the time, because that seems to work better for her gimpy right front wheel. What is it with right front wheels? At least Curiosity is changing things up by having problems with left-side wheels.)

The release states that Curiosity won't be driving backwards all of the time, just some of the time. (The reason they wouldn't do it all the time is because the RTG blocks the Navcam's view of the terrain immediately ahead of the rover when they're driving backwards, so they will probably stick to forward as much as they can, but have backwards driving "in the toolkit," as the release says, for driving on nastier terrain.)

[...]

And the rover's future traverse in yellow:

 

[IronRain]

Some strange footage from Mars:

[ame="http://www.youtube.com/watch?v=eh-wMjjLuwY"]Unidentified Light Source on Mars - YouTube[/ame]

There's a lot of talk going on in the UFO communities about this.

 

[Keatah]

I don't believe there is any wheel damage on spirit/oppy. The wheels were properly designed for the task. And for future rovers it's a matter of making them thick enough in the wear areas. There is a point where trying to "engineer out" that extra 5 grams is going to cost more than the value return - as we are now seeing.

Right now I bet the engineers would rather not have launched the dead weight of the half-functioning REMS experiment. They did too much cost cutting there too by not shielding the open ribbon cables. My $95 bargin bin monitor from wal-mart is better built. None of its delicate and critical parts are exposed.

Oh well. Sometimes the simplest solutions are the best.

 

[RGClark]

Some strange footage from Mars:

Unidentified Light Source on Mars - YouTube

There's a lot of talk going on in the UFO communities about this.

Meteor strike perhaps?

Bob Clark