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#276 2021-04-06 17:19:34

SpaceNut
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Video showing rover wheels wearing out

https://youtu.be/OlZIIWeLgio

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#277 2021-04-07 12:24:54

GW Johnson
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

I think I have commented before about these wheels:  aluminum is the simply wrong material to use to drive over rocks.  I don't care what alloy or cold-work strength,  or heat treatment.  It is the wrong choice for long life.

A nuclear-powered rover has an inherently long service life,  with essentially unlimited power.  What is the point of sending one of these to Mars,  if its wheels wear out and immobilize it in a couple of years?  BTW,  the new Perseverance rover has pretty much the same wheel design as Curiosity.  I know they say it's improved,  but it's still aluminum wheels on sharp rocks.

Once again,  stupid is as stupid does.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#278 2021-04-07 12:38:04

tahanson43206
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

For GW Johnson re #277

I was intrigued by your observations in this post ... the article at the link below is unapologetic

Surely the mission managers must have considered carbon based materials for the wheel ground contact surfaces ... I wonder how the decision making process, surely involving very smart, highly educated persons, would have resulted in the decision to stay with aluminum.

https://mars.nasa.gov/mars2020/spacecraft/rover/wheels/

I doubt very much the famous/infamous "brother-in-law" effect was at work.

There is too much at stake for NASA leadership to allow that.

(th)

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#279 2021-04-07 20:13:37

GW Johnson
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From: McGregor, Texas USA
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Carbon composite would be even worse than aluminum.  The failure stresses are even lower,  and the elongation-to-failure very far lower.

Driving in the rocks with non-inflatable wheels requires high tensile strength and large elongation-to-failure.  Period.  End-of-issue.  You also need strength when soaked out to extreme cold. 

As I said,  there is no point sending a rover to Mars with a power system lifetime of multiple decades,  and wheels that are useless in a couple of years.  Yet NASA has now done this mistake twice.

The material of choice for this is a 300-series stainless steel.  There is no other choice available.  I would recommend 304L,  myself.  A real materials guy might have something even better,  but odds are,  it'll be a 300-series stainless. 

Stupid is,  as stupid does.

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#280 2021-04-09 07:27:32

Quaoar
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

GW Johnson wrote:

Carbon composite would be even worse than aluminum.  The failure stresses are even lower,  and the elongation-to-failure very far lower.

Driving in the rocks with non-inflatable wheels requires high tensile strength and large elongation-to-failure.  Period.  End-of-issue.  You also need strength when soaked out to extreme cold. 

As I said,  there is no point sending a rover to Mars with a power system lifetime of multiple decades,  and wheels that are useless in a couple of years.  Yet NASA has now done this mistake twice.

The material of choice for this is a 300-series stainless steel.  There is no other choice available.  I would recommend 304L,  myself.  A real materials guy might have something even better,  but odds are,  it'll be a 300-series stainless. 

Stupid is,  as stupid does.

GW

Which is the weight difference between an aluminium wheel and a steel wheel of the same size?

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#281 2021-04-09 12:21:23

GW Johnson
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From: McGregor, Texas USA
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Quaoar:

For the same volume of parts,  the steel part is about 2.8 times heavier than the aluminum part. 

But,  what is the point of saving weight on the wheels,  if you cannot move the rover after about 2 years or so,  when it is nuclear-powered,  and would otherwise run around for decades?

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#282 2021-04-09 18:18:54

SpaceNut
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

An alloy with Titanium as well as other blends might be able to achive the goal of strong but light mass...

Then again there is the wire mesh lunar tire which might work but it needs to be tried and tested long before its sent....+


Sterling engine produces power from the RTG which has Plutonium...

Curiosity’s RTG was designed to supply about 125 watts continous….

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#283 2021-05-22 18:50:46

SpaceNut
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

60a8cb50e25d05001880cff1?width=1000&format=jpeg&auto=webp

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#284 2021-11-24 21:01:58

SpaceNut
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From: New Hampshire
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

NASA’s Curiosity Rover Sends a Beautiful Picture Postcard From MarsNASAs-Curiosity-Rover-Picture-Postcard-From-Mars-777x437.jpg
Blue, orange, and green color was added to a combination of the panoramas for an artistic interpretation of the scene.

On November 16, 2021 (the 3,299th Martian day, or sol, of the mission), engineers commanded Curiosity to take two sets of mosaics, or composite images, capturing the scene at 8:30 a.m. and again at 4:10 p.m. local Mars time. The two times of day provided contrasting lighting conditions that brought out a variety of landscape details. The team then combined the two scenes in an artistic re-creation that includes elements from the morning scene in blue, the afternoon scene in orange, and a combination of both in green.

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#285 2022-04-09 19:44:38

SpaceNut
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

Mars rover spots gusty weather blowing across the Martian desertAAW2xaV.img?w=680&h=385&m=6

Sometimes, Mars experiences extreme, long-lived dusty weather events, like dust storms. These storms can be huge, but they're also normal. "Every year there are some moderately big dust storms that pop up on Mars and they cover continent-sized areas and last for weeks at a time, And around every five years or so, a truly monstrous dust storm can encompass much of the planet.

In this dusty world, the Curiosity rover continues to gradually climb a region called Mount Sharp, which is a peak inside Mars' Gale crater. The NASA robot seeks to determine if the planet could have ever been habitable enough for tiny microbes to thrive, perhaps in the moist soils of lake beds or streams.

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#286 2022-06-05 04:28:31

Mars_B4_Moon
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

NASA Rover Spots Extremely Weird Spikes on Mars
https://futurism.com/the-byte/nasa-rove … pikes-mars
Curiosity's next fascinating discovery: two ancient "spikes" of cemented rock


NASA Remotely Hacks Curiosity’s Rock Drill
https://hackaday.com/2018/05/25/nasa-re … ock-drill/

We have a lot of respect for the hackers at NASA’s Jet Propulsion Laboratory (JPL). When their stuff has a problem, it is often millions of miles away and yet they often find a way to fix it anyway. Case in point is the Curiosity Mars rover. Back in 2016, the probe’s rock drill broke. This is critical because one of the main things the rover does is drill into rock samples, collect the powder and subject it to analysis. JPL announced they had devised a way to successfully drill again.

The drill failed after fifteen uses. It uses two stabilizers to steady itself against the target rock. A failed motor prevents the drill bit from retracting and extending between the stabilizers. Of course, sending a repair tech 60 million miles is not in the budget, so they had to find another way. You can see a video about the way they found, below.

NASA calls what happened “MacGyvering.” The drill bit is fully extended at all times. Now the rover has to use the entire arm to push the drill forward and recenter without the stabilizers. The arm has a force sensor made to detect if the arm strikes something. That sensor now has a new purpose, to monitor the progress of the drilling.

NASA's Curiosity rover finds a mysterious doorway on Mars, spark speculations
https://www.cnbctv18.com/science/nasas- … 607052.htm

Rover used its Mast Camera, or Mastcam, to capture this mound of rock nicknamed “East Cliffs”


PDF link
Drill samples already taken uncovered organic molecules of benzene
https://authors.library.caltech.edu/869 … ode-SM.pdf

and propane in 3 billion year old rock samples in Gale

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