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Spring at Cape York, Sol 2947 (after Greeley Haven) - sol 3040
Stu
post Jun 7 2012, 03:37 PM
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"Monte Cristo" in all its glory...

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Phil Stooke
post Jun 7 2012, 04:06 PM
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Nice one, Stu!

Phil



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walfy
post Jun 8 2012, 06:33 PM
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A micro from sol 2974, "Monte Cristo":

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RoverDriver
post Jun 8 2012, 07:48 PM
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Darn! Nowadays I get one shift every two weeks or so. Today I was on shift and no driving due to ODY being in safe mode! mad.gif My next shift is in three weeks!

Paolo


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Phil Stooke
post Jun 9 2012, 11:01 AM
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That safe mode could last until August, they say now. Ready in time for Curiosity's landing, but not good news for Opportunity.

Phil



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Stu
post Jun 9 2012, 12:31 PM
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The latest PDS release covers Sols 2701-2790, which includs the time Oppy spent approaching, studying and then destroying "Homestake"... A couple of pics made using the PDS images, shown here in advance of Oppy spotting a bigger, fatter "Homestake" to use her instruments on...

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Very pleased with the second one - first time I've been able to see and bring out the "sparkly bits" referred to by the rover team smile.gif


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Floyd
post Jun 9 2012, 01:59 PM
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QUOTE (Phil Stooke @ Jun 9 2012, 07:01 AM) *
That safe mode could last until August, they say now. Ready in time for Curiosity's landing, but not good news for Opportunity.
Phil


The report on the Odyssey site doesn't seem that dire: "NASA's Mars Odyssey orbiter put itself into a precautionary standby status early Friday, June 8, Universal Time (Thursday evening, Pacific Time), when the spacecraft detected unexpected characteristics in movement of one of its reaction wheels. The spacecraft uses three of these wheels as the primary method for adjusting and maintaining its orientation. It carries a spare reaction wheel.""The spacecraft is safe, and information we've received from it indicates the problem is limited to a single reaction wheel," said Odyssey Mission Manager Chris Potts of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The path forward is evaluating the health of the reaction wheel and our options for proceeding."

Hopefully that means a week or so unless you have more specific information Phil.


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Phil Stooke
post Jun 9 2012, 02:02 PM
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I was going by this, maybe a bit alarmist...

http://news.yahoo.com/nasa-troubleshoots-p...-232759130.html



Phil


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mhoward
post Jun 9 2012, 02:13 PM
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Perhaps to journalists, publicists and the general public, the main point is that it should be operating normally when Curiosity gets there. Of course the rest of us would like to see it operating normally considerably before then rolleyes.gif
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Matt Lenda
post Jun 10 2012, 04:09 PM
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QUOTE (Floyd @ Jun 9 2012, 06:59 AM) *
The report on the Odyssey site doesn't seem that dire: "NASA's Mars Odyssey orbiter put itself into a precautionary standby status early Friday, June 8, Universal Time (Thursday evening, Pacific Time), when the spacecraft detected unexpected characteristics in movement of one of its reaction wheels. The spacecraft uses three of these wheels as the primary method for adjusting and maintaining its orientation. It carries a spare reaction wheel.""The spacecraft is safe, and information we've received from it indicates the problem is limited to a single reaction wheel," said Odyssey Mission Manager Chris Potts of NASA's Jet Propulsion Laboratory, Pasadena, Calif. "The path forward is evaluating the health of the reaction wheel and our options for proceeding."

Hopefully that means a week or so unless you have more specific information Phil.

That's the feeling I'm getting around the office. Chris isn't hiding anything in his oh-so-very-PR statement! It was just a bit of funny data that the spacecraft didn't like.

She's an old bird, the one...

Needless to say the MSL folks are a little rattled.

-m
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elakdawalla
post Jun 11 2012, 08:34 PM
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It's kind of amazing to me that with all the electronic complexity of spacecraft, one of the things that most reliably fails is....THE WHEEL. Hayabusa, FUSE, Cassini....Seriously, you'd think humans would've got the hang of The Wheel by now.


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Floyd
post Jun 11 2012, 11:17 PM
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Does anyone know if the WHEELS have magnetic or ball bearings? Is it the bearings that usually fail, or some other component?


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Matt Lenda
post Jun 12 2012, 04:51 AM
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QUOTE (Floyd @ Jun 11 2012, 03:17 PM) *
Does anyone know if the WHEELS have magnetic or ball bearings? Is it the bearings that usually fail, or some other component?

Usually magnetic, to reduce all friction that you can. There's even the concept of "stiction" across the 0-rpm boundary, when the wheel is spinning very slowly but then crosses 0-rpm and goes the other direction -- even great reaction wheels can get a little "stuck" at that point. Some missions can have attitude control systems that will explicitly avoid 0-crossings, but it often cannot be avoided, depending on your pointing profile.

Wheels are indeed tricky -- just ask Oppy!

-m
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Tesheiner
post Jun 14 2012, 06:24 AM
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Just a pair of F/RHAZ pics came down on the last batch, but confirming that Opportunity is now located quite close to the edge.
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Original: http://qt.exploratorium.edu/mars/opportuni...P9P1312L0M1.JPG

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RoverDriver
post Jun 14 2012, 06:03 PM
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QUOTE (Floyd @ Jun 11 2012, 04:17 PM) *
Does anyone know if the WHEELS have magnetic or ball bearings? Is it the bearings that usually fail, or some other component?


If you are asking about the reaction wheels on ODY, I have no idea, on MER drive/steer actuators they have bearings and magnetic detents. In Oppy's RF steering actuator it is believed that the magnetic detent came loose and prevents motion, while in Oppy's IDD Az actuator we have reasons to believe it is one of the windings that is no longer operational. In Spirit's RF and RR drive actuator it is less clear but the best explanation I have heard is that there is some kind of deposit on the commutators which prevent current to flow through the windings.

Paolo


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