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#226 2013-12-21 18:24:11

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

GW Johnson wrote:

Oops.  Aluminum wheels may not have been the best choice for a long-life nuke rover.  News stories today indicate unanticipated rates of wear attributed to rough ground. 

Everybody who has ever hiked around in the mountains knows how rough that kind of ground can be.  Not sure whether weight or cost drove them to aluminum wheels,  but I'd bet that team is regretting that choice now.

GW

That does seem an odd choice, given the weight of the rover and the rough ground. What would you have suggested GW? Was the reason they chose aluminium because of the way it behaves in extremely cold weather?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#227 2013-12-21 18:35:47

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

I would have put a 300-series stainless steel tire on that aluminum rim. 

300-series stainless is what they use for cryo-propellant storage tanks here on Earth,  because it will handle the cold better than any other known material,  bar none. 

It is tough in the sense of a huge elongation to failure (as steels go).  It is unaffected by corrosive chemistry to a great extent.  And any steel alloy beats the crap out of aluminum for resistance to rock impact. 

But then,  I am an engineer,  not a scientist.  Must have been some reason they did what they did.  Just nothing I can comprehend. 

GW

Last edited by GW Johnson (2013-12-21 18:37:20)


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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#228 2013-12-22 10:47:55

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

Its called planned obseolescence

New Mars Rover Could Far Outlive Its Lifespan

The Curiosity rover is carrying a nuclear power source to charge its batteries and fuel its onboard systems throughout its planned two-year mission on Mars. The system uses heat from the decay of plutonium-238 to generate 110 watts of electrical power to charge the rover's batteries. "The RTG suffers from the degradation of plutonium dioxide, but that lasts a long time," Theisinger said. "I think from the RTG, I would expect to get 10, 12 or 15 years out of it."

Theisinger said.

While the rover could realistically survive five or six years on Mars, there are three main areas that could limit Curiosity's life: the rover's onboard mechanisms, its batteries, and its nuclear-powered RTG, he explained.

"We test the mechanisms usually for three times life — sometimes two — and we don't test them to failure," Theisinger told SPACE.com. "So, all the mechanisms have been tested to last two to three times longer than we expect the mission to operate, if they haven't failed in that period of time."

The rover's batteries and RTG are designed to operate on Mars for at least 687 Earth days, but could endure for longer.

There we have it the batteries are the weak link and there fore the most time that any part must last for duration of operation..

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#229 2014-01-05 10:28:54

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

Curiosity-Sol-494_1a_Ken-Kremer--580x463.jpg

Now, dents and scratches I don't mind so much, but look closely at the top right-hand quadrant of this wheel.
There's a hole torn right through the wheel! yikes
And just down from that hole, I think I'm seeing a small split in the metal.

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#230 2014-01-05 20:07:59

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

Looks to me like the wheels are the weak link.  That's sad,  because this thing is supposed to go off-roading into the rocky slopes of a mountain,  not roll around in the soft sand.  I have a really hard time believing this.  But there it is,  in the photo.

GW


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

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#231 2014-02-01 18:50:15

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

Definitely a weak link in design so Curiosity Mars Rover Checking Possible Smoother Route in an attempt to skirt some terrain with sharp rocks considered more likely to poke holes in the rover's aluminum wheels. The team now drives the rover with added precautions, thoroughly checks the condition of Curiosity's wheels frequently, and is evaluating routes and driving methods that could avoid some wheel damage.

Curiosity has driven 865 feet (264.7 meters) since Jan. 1, for a total odometry of 3.04 miles (4.89 kilometers) since its August 2012 landing.

They sure need to solve why its happening....

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#232 2014-02-13 10:58:17

Number04
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Re: Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT

I heard Kobie Boykins talk about the wheels just this week. The reason they are thin aluminum is that they mimic rubber tires here on earth. The wheels get more grip, but take more damage.

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#233 2014-02-14 17:10:01

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

Mimic a rubber tire with thin aluminum?  In the rocks?  You have to be kidding me! 

No one ever built a successful wheel like that here.  Never.  Not ever. 

I think these labs should be talking to some real,  dirty-fingernails engineers like me and a bunch of others I could name.  They certainly don't seem to have anyone like that on their staffs.

GW


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

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#234 2014-09-12 10:58:26

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

I see by the news releases that Curiosity has reached the foothills of Mount Sharp.  The wheel damage issue slowed them and modified their route,  but they made it.  I hope failed wheels don't "kill" the thing early.  It's always quite rocky in mountainous areas here.

On the way,  there was one striking photo they obtained that created something of a stir:  an oddly shaped rock that looked like a thighbone.  The soil colors and rock outlines in the dirt looked rather similar to the Mount Sharp foothills stuff,  so it must be fairly close by where they are now.  That odd rock was interesting enough that I hope they poked around a bit,  investigating it,  before resuming the trek.  To me it looked there were cavities under some of those mostly-buried slabs.  That's a rather nifty site. 

But,  I only ever saw the one photo of the "thighbone" site,  and nothing about it since. 

GW


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

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#235 2015-02-22 18:10:22

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

Just trying to keep Maven topic on its discoveries:

GW Johnson wrote:

This is an example of only one way (out of a gigantic plethora of ways) that ground truth can be so vastly different from expectations and remote sensing results.  Sometimes we shoot ourselves in the foot out of ignorance,  as described below.  Other times,  Mother Nature shoots us in the foot by refusing to conform to our expectations ,  measurements,  and theories.  Either way it happens all the time.  The smart mission planner takes this into account as a failure he assumes will happen.

GW

Copied off MSNBC news on the internet,  from their “Science” section:

Curiosity's experiments on Martian soil may be inadvertently eliminating traces of organics, British researchers reported this week. One of the compounds the rover is on the lookout for is jarosite, a mineral associated with conditions potentially suitable for life. Curiosity tests for jarosite and other interesting substances by flash-heating soil samples, watching for telltale signs of certain elements.

Tests conducted by a team at Imperial College London show that this heating process may cause the jarosite to break up and give off free oxygen — which can then destroy organic compounds in the soil. Essentially, the testing method could eliminate what it's looking for in the process.

RobertDyck wrote:

I did a quick Google, and found the paper that GW Johnson talked about. The original on the website for Imperial College London.
Scientists identify mineral that destroys organic compounds

This is highly important. When Opportunity examined Meridiani Planum, they found jarosite. That's important because it's a sedimentary mineral that only forms in mildly acidic water. Dr. Carol Stoker studied the possibility that life could have arisen there. So I looked at this myself. Scientists can trace how life evolved from simpler forms, and DNA could have evolved from RNA, but how did RNA first form? The steps to form RNA are complex, and some require conflicting conditions. Some require acid, others require alkali. But I pointed out jarosite demonstrates there was acidic water, and Meridiani Planum is surrounded by normal Mars dust, which is dominated by plagioclase feldspar, which is alkali. Wind would blow dust into the water, so this alkali dust could change the pH. Meridiani Planum has hematite concretions, which are the catalyst for fischer tropsch catalysis, which combines small simple hydrocarbons to form large complex ones. And sediment in some areas is finely layered clay, which is the catalyst to combine phosphate and ribose sugar with pyrimidine and purine to form nucleotides. Meridiani Planum has borite, which is the catalyst that preferentially forms ribose sugar. And phosphate is simple phosphorus oxide, which is present there. It's an evaporite plane, so changing solute concentration. Ribose sugar requires water without any nitrogen, but pyrimidine and purine require nitrogen. I could go on, but all the conditions for genesis of RNA world are (were) present at Meridiani Planum. And at the 2005 Lunar and Planetary Science Syposium, geologists reported an imbalance between bromine salts vs other salts. Dr. Carol Stoker pointed out astrobiologists like herself look for exactly that type of imbalance to indicate past action of single cell organisms.

Dr. Carol Stoker told me that the source of sulphur at Meridiani Planum is believed to be a hot spring. She was studying a hot spring at Rio Tinto in Spain as a comparison. Is there anything like that where Curiosity is located?

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#236 2015-02-22 18:23:17

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

Response posted in other topic:

SpaceNut wrote:

try number 2...

The rovers did go through a sulfur laiden location as the tracks from the rover did disturb the soil.

Mars Exploration Rovers (MER) on pg 16
Official MSL / Curiosity Rover Thread | Aug 5, 2012 10:31 p.m. PT on pg 9

Edit to add more information.

Typical file image from opportunity:
pancam-mars-merb-west-rim-endeavour-crater-lg.jpg

notice the tracks....

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#237 2015-02-27 21:23:43

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

NASA's Curiosity Mars Rover Drills at 'Telegraph Peak'

The target sits in the upper portion of "Pahrump Hills," an outcrop the mission has been investigating for five months.
The rover team is planning to drive Curiosity away from Pahrump Hills in coming days, exiting through a narrow valley called "Artist's Drive," which will lead the rover along a strategically planned route higher on the basal layer of Mount Sharp.
Compared to the chemistry of rocks and soils that Curiosity assessed before reaching Mount Sharp, the rocks of Pahrump Hills are relatively enriched in the element silicon in proportion to the amounts of the elements aluminum and magnesium. The latest drilling site exhibits that characteristic even more strongly than the earlier two, which were lower in the outcrop.

"When you graph the ratios of silica to magnesium and silica to aluminum, 'Telegraph Peak' is toward the end of the range we've seen

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#238 2015-03-15 20:50:07

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

Update: Curiosity uses arm and resumes journey up Mount Sharp

Curiosity_sol903-map-artists-647x404.jpg

After remaining still for several days in order to provide engineers a chance to diagnose a transient short circuit in its drill, NASA’s Mars Science Laboratory rover Curiosity is once again on the move. On Wednesday, March 11, Curiosity moved its robotic arm to transfer sample rock powder from its drill to its Chemistry and Mineralogy instrument (ChemMin). This is the same action that Curiosity was attempting when the short occurred on Feb. 27.

The rover team plans on taking Curiosity through a valley called “Artist’s Drive” to reach higher geological layers of Mount Sharp. Curiosity is currently heading towards a rock outcrop known as “Garden City.”

Showing more signs of aging

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#239 2015-03-22 16:24:59

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

Say What? Possible fatty acid detected on Mar

A fatty acid might be among organic molecules discovered on Mars by Nasa's Curiosity rover. However, it's not possible at this stage to determine whether the compound has a biological or non-biological origin. And contamination could still be responsible for the finding.

A long-chain carboxylic acid, or fatty acid, was a good fit for one of the data peaks detected in a mudstone called Cumberland, he told an audience at the meeting. A form of alcohol molecule may also be among the compounds analysed.

The preliminary result will excite scientists because fatty acids are key components of the cell membranes found in all life forms, including microbial organisms.

The instrument team has previously reported evidence of chlorobenzene in the same rock, from the Martian area known as Yellowknife Bay.

Wow proof of past life lets start getting ready to go....

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#240 2015-07-15 20:33:20

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

http://www.sciencedaily.com/releases/20 … 142051.htm

Curiosity rover finds evidence of Mars' primitive continental crust
ChemCam instrument shows ancient rock much like Earth's

The ChemCam laser instrument on NASA's Curiosity rover has turned its beam onto some unusually light-colored rocks on Mars, and the results are surprisingly similar to Earth's granitic continental crust rocks. This is the first discovery of a potential "continental crust" on Mars.

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#241 2015-09-12 20:46:09

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

Mars Panorama from Curiosity Shows Petrified Sand Dunes

pia19818-16.jpg

Large-scale crossbedding in the sandstone of this ridge on a lower slope of Mars' Mount Sharp is typical of windblown sand dunes that have petrified.

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#242 2016-02-11 21:32:58

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

Here is a dune selfie shot and the tires are looking a little more beat up...

this-is-curiositys-latest-selfie-in-bagnold-dunes-composed-of-57-different-photos-captured-on-january-19-to-test-the-sands-the-rover-recently-dug-one-of-its-20-inch-wheels-into-a-nearby-dune-you-can-see-the-tire-marks-in-the-center.jpg

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#243 2016-04-03 20:13:11

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

Nasa create a simulation that made a small crater go through a process of being wet inside of a wind tunnel to see if they could create the process of the formation of the mounds in those seen on mars....with captured images being quite simular in shape as to the one's on mars.

Mysterious Mars Mounds Were Liquid-Filled Craters

dnews-files-2016-04-mars-gale-crater-670-jpg.jpg

On Mars, formerly water-filled craters transformed to dry mile-high mounds with the help of wind, according to new research. The results explain the geography of Gale Crater (the Curiosity rover’s landing site) as well as other high-topped places on the Red Planet, and confirm that wind is currently the dominant force in Mars’ geology. Analysis of 30 mounds on Mars nails down their deposition to the Noachian period 3.7 billion years ago, as the mounds are only seen on terrain that was available at that time. The Noachian is thought to represent the boundary period between Mars’ wet past and dryer present.

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#244 2016-08-06 20:09:43

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

March 24, 2015: NASA's Curiosity Rover Finds Biologically Useful Nitrogen on Mars
This is over a year old, but very important. How did we miss it?

A team using the Sample Analysis at Mars (SAM) instrument suite aboard NASA's Curiosity rover has made the first detection of nitrogen on the surface of Mars from release during heating of Martian sediments. The nitrogen was detected in the form of nitric oxide, and could be released from the breakdown of nitrates during heating. Nitrates are a class of molecules that contain nitrogen in a form that can be used by living organisms. The discovery adds to the evidence that ancient Mars was habitable for life.

After Europe's Mars Express found traces of ammonia in the upper atmosphere, I speculated that the source was decomposition of soil nitrates. My hypothesis: when nitrates are exposed on the surface, current conditions break them down to nitride. A combination of the anoxic atmosphere, cold, and intense UV light causes this. Then a warm day melts permafrost, causing liquid water to trickle across the surface. When water touches alkali metal nitride, it decomposes to ammonia. Hydrogen from water combines with nitride to form ammonia, oxygen from water combines with the metal to form metal oxide. Probes have found metal oxide on the surface, although there are other ways to form it. This would explain ammonia without any microorganism. It also explains why no nitrates are visible on the surface.

So Curiosity found nitrates. Very important for terraforming. Would help with greenhouses as well.

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#245 2017-01-02 22:53:07

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

Was reminded of last months Boron find...

NASA’s Curiosity Discovers Boron On Mars

But found an earlier news story about  Mars Clay Harbored Boron, Key Element For Life, Meteorite Study Suggests

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#246 2018-12-22 21:31:09

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

"Gale Crater, and more specifically, Mount Sharp, was the target of study for Curiosity when it landed on Mars  August 6, 2012," its hard to believe but its sure is going slowly.

Composite View of Gale Crater Show's Curiosity rover's Landing Spot

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#247 2019-02-03 20:23:39

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

The researchers accomplished this by recalibrating the accelerometers on NASA's Curiosity rover to detect changes in the planet's gravitational tug as it ascends the slope.

"Gravimetry can help scientists understand a planet's interior structure," Morrison explained.

Between October 2012 and June 2017, the researchers made more than 700 such measurements using Curiosity's accelerometers, comparing them to models of Mars' gravity fields and to estimates of its mineral density.

"Working from the rocks' mineral abundances as determined by the Chemistry and Mineralogy instrument, we estimated a grain density of 2,810 kilograms per cubic meter," he said. "However the bulk density that came out of our study is a lot less - 1,680 kilograms per cubic meter."

The much lower figure shows that the rocks have a reduced density most likely resulting from the rocks being more porous. This means the rocks have been compressed less than scientists have thought.

http://www.marsdaily.com/reports/Resear … s_999.html

http://www.marsdaily.com/reports/Mars_R … e_999.html

http://www.marsdaily.com/reports/What_C … d_999.html

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#248 2019-02-27 21:35:05

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

I recall the other rovers having an issue with the firmware on the other rovers and they all seems to be stepping on the boot and memory use tables...

NASA engineers are investigating Curiosity probe's computer reset

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#249 2019-03-17 16:11:17

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

Something for fixing the baseline rover design for the next builds:

kbd512 wrote:

The durability of Aluminum wheels for ground vehicles could be greatly improved by using Aluminum CMC's (Ceramic Metal Matrix Composites).  These alloys uniformly mix various loadings of Alumina Oxide nanoparticles with the Aluminum metal instead of Copper or Nickel or other alloying metals.  The hardness of the material, prior to any sort of heat treatment, is such that carbide or diamond tipped cutting tools and slower feed rates are require for machining.  The manufacturer doesn't use any heat treatments, as that's a selling point of the material- no heat treatment required to achieve mechanical properties identical to 2xxx / 6xxx / 7xxx alloys, apart from hardness and greatly improved strength at elevated temperatures.  They have material variants for forging, casting, and welding.  The cost of the material is approximately the same as 316 Stainless Steel.  It's more expensive than regular 2024 or 6061, but less expensive than Titanium alloys and a lot lighter.

This seems to be a hole in the wheel fix...

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#250 2019-05-31 20:15:24

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

One only needs to look at what we have learned to know that we are still learning as Curiosity Mars Rover Finds a Clay Cache

mars-science-laboratory-curiosity-rover-selfie-may-2019-hg.jpg

Something else of interest is the water in the air.....

Cameras (Navcams) to snap images of drifting clouds on May 7 and May 12, 2019, sols 2400 and 2405. They're likely water-ice clouds about 19 miles (31 kilometers) above the surface.

The mission's team has been trying to coordinate cloud observations with NASA's InSight lander, located about 373 miles (600 kilometers) away, which recently took its own cloud images. Capturing the same clouds from two vantage points can help scientists calculate their altitude.

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