Opportunity Mission Update Thread

[ilbasso]

My reckoning is that the heatshield's terminal velocity was in the neighborhood of 120 mph, more or less. I didn't have the exact diameter of the heatshield but I estimated it from photos with people standing next to it.

 

[Swampcat]

This SDC article, Mars Rover Wanders Through Littered Landscape, has some information on Oppy's heatshield.<br /> <div class="Discussion_UserSignature"> <font size="3" color="#ff9900"><p><font size="1" color="#993300"><strong><em>------------------------------------------------------------------- </em></strong></font></p><p><font size="1" color="#993300"><strong><em>"I hold it that a little rebellion now and then is a good thing, and as necessary in the political world as storms in the physical. Unsuccessful rebellions, indeed, generally establish the encroachments on the rights of the people which have produced them. An observation of this truth should render honest republican governors so mild in their punishment of rebellions as not to discourage them too much. It is a medicine necessary for the sound health of government."</em></strong></font></p><p><font size="1" color="#993300"><strong>Thomas Jefferson</strong></font></p></font> </div>

 

[odysseus145]

I just saw this pancam image from sol 151. Does anyone know what the white material is in the image? <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

Since it's the L7 filter, we know it's really bright in the UV. There seems to be a type of rock the rover drives over, that is very soft and breaks up into this UV bright powder. Other ideas (that I find less credulous) include that this is an ice/dust mixture (ice is also bright in the UV).<br /><br />Microscopic imager pics of dark and bright dirt shows that there is bright dirt and dark dirt.<br /><br />Anybody have results from the Mossbauer that tells chemical composition?

 

[fangsheath]

The latest update confirms that dust storms are an issue for Opportunity, although so far they are described as local phenomena. As to whether the vehicle could survive a large-scale storm, I'm not sure. A thick dust pall would likely preclude any solar power generation. Even starting at a full charge and using power only for the barest essentials, I doubt the vehicle could live more than a month. On the other hand, if the opacity dropped for even one day out of five, enough for the panels to charge the batteries, the rover might survive indefinitely. I hope we don't have to find out.

 

[fangsheath]

In this piece we can see the heatshield better in cross section. I believe the top layer is the aluminum honeycomb, the bottom the phenolic material filled with the ablator.

 

[thechemist]

This *highly* unusual rock lies close to the heatshield. I am sure it will be studied extensively pretty soon.<br /><br />pancam image <div class="Discussion_UserSignature"> <em>I feel better than James Brown.</em> </div>

 

[JonClarke]

It may be a long shot, but the texture of this rock, smooth, shiny matrix with sunken rough blobs looks very much like a stony iron meteorite. Meteorites are likely to be common on the surface of mars because of lower weathering and erosion rates and proximity to the asteroid belt.<br /><br />http://www.astro.washington.edu/labs/clearinghouse/labs/Meteors/images/hst_brenham.jpg <br /><br />http://www.meteorlab.com/METEORLAB2001dev/brenham.htm<br /> <br />http://monnigmuseum.tcu.edu/meteorites/estherville.htm<br /><br />http://hyperphysics.phy-astr.gsu.edu/hbase/solar/meteor3.html<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Looks like I might be right. Metal is a strong pointer towards a meteorite. <br />http://www.space.com/missionlaunches/mars_object_050113.html<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[astrophoto]

It certainly LOOKS like a meteorite, and looks metallic. Would love to see the actual data on it.<br /><br />Being so close to the belt and the surface being what it is, it might be a great place to send a 'meteorite finder' mission. It would be much more cost effective than sending intercept missions into space to intercept a single object.

 

[centsworth_II]

I wonder if they'll chance RATing it. It would be a shame to damage the RAT on a chunk of metal. <div class="Discussion_UserSignature"> </div>

 

[bobvanx]

>>meteorite<br /><br />Well done, sir! The team seems to think the same thing!<br /><br />I was wondering why it would be exciting to find an iron or iron/nickel meteorite on Mars. Then I realized that there are data you can capture from it, that you can't get with these rovers any other way.<br /><br />I think the surface melting of these kinds of meteorites is fairly well characterized? Clearly you need atmospheric friction to melt the surface, I wonder if they can deduce whether this rock fell when the atmosphere was thin, or thick?

 

[silylene old]

Good eye, Jon !<br /><br />The less dense atmosphere should mean that the meteorite endured less intense heating during entry into the atmosphere cmopared to a meteorite on Earth.<br /><br />More interesting, I wander how long that meteorite might have been sitting there? It bet it had once been buried, and is now excavated by erosional processes. <div class="Discussion_UserSignature"> <div class="Discussion_UserSignature" align="center"><em><font color="#0000ff">- - - - - - - - - - - - - - - - - - - - - -</font></em> </div><div class="Discussion_UserSignature" align="center"><font color="#0000ff"><em>I really, really, really miss the "first unread post" function.</em></font> </div> </div>

 

[thalion]

I doubt it's a stony-iron--those are the rarest category of meteorite. Irons are easy to find, but actually a minority of actual falls. If it's a real meteorite, I'm guessing odds are its a stony--however, as I said mentioned irons are easiest to find.

 

[bobw]

Wow Jon, you called that one.<br /><br />Will they be able to tell how long ago it hit? Can they do dating with the alpha particle x-ray spectrometer or whatever it s called? If it got heated good enough on the outside to reset the clock? Or will it take a mass spectrometer? <div class="Discussion_UserSignature"> </div>

 

[JonClarke]

I imagine some sort of cosmogenic isotope method could be used. Ii read a paper about in situ dating of martian materials a while back, I will look for it and post a precis next week.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[bobw]

Thanks, just don't waste a lot of time for me. I thought you might know off the top of your head. It seems like every time I read about dating there are ways to figgure out anything. Thanks again. I hope I don't make you feel like the answer man or something. Just knowing it may be possible makes me feel like I was in the ballpark. <div class="Discussion_UserSignature"> </div>

 

[jaredgalen]

Cant'wait to see what they find out.<br />http://qt.exploratorium.edu/mars/opportunity/forward_hazcam/2005-01-15/1F158988828EDN40DPP1131L0M1.JPG

 

[bobvanx]

A color corrected image of a frosty morning at Meridiani! Note that the mirrors are pale blue.

 

[odysseus145]

Confirmation! <div class="Discussion_UserSignature"> </div>

 

[astrophoto]

So a basketball sized Ni-Fe meteorite just sitting there on the surface without the slightest scar or impression on the surface. Surely this may lead to some interesting conclusions on surface dynamics. It was either transported or hit in the same general area but at a much higher land level that then eroded around it. It can't be 'new' because there would HAVE to be some signs of impact for something so heavy.

 

[thalion]

It's always possible that it entered at a very low angle, thereby leaving little or no sign of impact--think of the massive Hoba meteorite.

 

[bobvanx]

I looked up info about Hoba, it seems that it is "small" enough to have decelerated to terminal velocity (I can't imagine!!!)<br /><br />Perhaps Mar's tenuous atmosphere is dense enough that this meteorite slowed down enough so that... it didn't... make... a dent...<br /><br />...but, the heat shield, which is far less dense than an iron/nickel meteriote, made a dent, and it was certainly traveling slower than this meteorite would have been?<br /><br />C'mon, Dr. Squyres, somebody on yer team has to have the imagination to see that something interesting is being demonstrated for us, here!

 

[JonClarke]

Hi Bob<br /><br />As promised, here is the summary of possible methods from Doran et al. (2004), "Mars chronology: assessing techniques for quantifying surficial processes," Earth Surface Processes and Landforms 67: 313-237.<br /><br />The authors look at four methods:<br /><br />1. Direct gamma ray detection<br /><br />A high spectral resolution and high sensitivity detector could identify the presence and abundances of short lived isotopes like Na22, Al 26, and Co60 to dtermine exposure age and longer lived isotopes like K40 and the U-Th series to date host rocks.<br /><br />2. Luminescence methods. The high cosmic radiation, low natural radioactivity of Mars materials, and uncertainities about martian processes renders this method problematic at present.<br /><br />4. Noble gas methods. Mass spectrometers can measure abundances of He3, Ne21, Ar36. and Ar38 for both cosmogenic and whole rock dataing.<br /><br />5. Standard radiogenic techiques. Laser ablation ICP-Mass Spectroscopy should be able to perform Rb-Sr dating on rocks.<br /><br />Cheers<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>

 

[JonClarke]

Several things to remember Borman. This meteorite is very small, I guess about 10-20 cm. Even on earth such meteorites make very small pits when they hit, on Mars, the gravity is only 38% of earth's, so the pit should be smaller. The other is that the meteorite is probably been there for a very long time - it isn't going to rust away after all. So there has probably been erosion and/or redistribution of the surface, obliterating the crater.<br /><br />Jon <div class="Discussion_UserSignature"> <p><em>Whether we become a multi-planet species with unlimited horizons, or are forever confined to Earth will be decided in the twenty-first century amid the vast plains, rugged canyons and lofty mountains of Mars</em>  Arthur Clarke</p> </div>