My Assistant
| Posted on: Jun 5 2013, 02:49 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
According to this LPSC 2012 paper Mastcam is more sensitive to red near 676nm than MAHLI according to this MSL Science Corner article. I'm a coauthor on the LPSC abstract and you can't really get that level of detail out of those figures IMHO. There's no debate that there are slight color differences between the cameras. They are not intentional. We didn't do anything to explicitly balance the colors; the raw images are just what's coming out of the camera. The differences are caused by the spectral transmissions of the lenses and the slightly different bandpasses of the IR cut filters. I spent quite a bit of time on the color-corrected archive products, which have been delivered to PDS, but I don't know when they will be released. And there will still be some uncertainty about what "color-corrected" means; I tried to be explicit in the documentation about exactly what the processing entailed, but radiometry is complicated and these instruments are cameras, not colorimeters or spectrometers. |
| Forum: MSL · Post Preview: #200716 · Replies: 529 · Views: 461044 |
| Posted on: Jun 4 2013, 09:45 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
those images SHOULDN'T look the same. Quite. Also, we acknowledge that the uncorrected color between MAHLI and Mastcam is slightly different. wildespace, you can stop making this point. The PDS delivery will have color-corrected versions of all images, and then you can argue about those if you wish. |
| Forum: MSL · Post Preview: #200700 · Replies: 529 · Views: 461044 |
| Posted on: Jun 4 2013, 11:47 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
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| Forum: MSL · Post Preview: #200690 · Replies: 529 · Views: 461044 |
| Posted on: Jun 3 2013, 06:37 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
JHow cool would it be for Curiosity to take a self portrait at night!... Is this possible? The LEDs become very dim at distances of more than a few centimeters (inverse-square law). You could potentially take an image of something like the RSM with the LEDs and a long-enough exposure, but I question if it would be that interesting. |
| Forum: MSL · Post Preview: #200662 · Replies: 529 · Views: 461044 |
| Posted on: Jun 2 2013, 03:47 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
whether we'll later be able to enjoy a Mastcam Left movie following a falling sample in slo-mo... Depends on what you mean by "slo-mo". If I take a 1 frame/sec movie and play it back at 1/2 frame/sec than that's technically "slow motion" but it will look pretty jerky. The Mastcam frame rate at 720P resolution is only something like 10 fps, and even tiny subframes can only speed that up so much. I wouldn't call the results "slo-mo" relative to the standard commercial 30 fps video rate. |
| Forum: MSL · Post Preview: #200642 · Replies: 285 · Views: 225750 |
| Posted on: Jun 2 2013, 03:14 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Perhaps radiation-sensitive payloads may have to take advantage of transfer orbit windows that occur during quiet sun periods? The paper says that only about 5% of the total dose MSL saw in cruise was from solar events, the rest being from galactic cosmic rays. GCR dose rate is thought to be weakly anticorrelated with the solar cycle. They do point out that "the SEP contribution could conceivably be many times larger in a different time frame" (i.e., closer to solar max.) |
| Forum: MSL · Post Preview: #200636 · Replies: 70 · Views: 98400 |
| Posted on: Jun 1 2013, 03:39 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
It's nevertheless hard to infere without more infos from the team. Unfortunately there is no public information I can point you to about all the video modes and options; this information will be in the PDS release which by the schedule should occur next month. For now I'll just say that your conjectures are perfectly reasonable. |
| Forum: MSL · Post Preview: #200617 · Replies: 285 · Views: 225750 |
| Posted on: May 20 2013, 09:26 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
why yes? I have not decided on endeavor of reaches but the question of black particles seem critical and new flat field data seems appropriate. I can't parse this completely, but note that these are raw images without any flat-field correction. I was unable to find any sensor crud in this image that wasn't there before launch. |
| Forum: MSL · Post Preview: #200302 · Replies: 285 · Views: 225750 |
| Posted on: May 20 2013, 02:16 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
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| Forum: MSL · Post Preview: #200292 · Replies: 285 · Views: 225750 |
| Posted on: May 19 2013, 02:18 AM | ||
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
The likely failure point will not be on the wheel tread surface itself, but at the annulus on the inner surface where the wheel spokes attach to the wheel. I'm not following your reasoning; the entire tire is one piece of aluminum, beefed up where the flexures attach. Maybe the slide I referenced will be useful. |
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| Forum: MSL · Post Preview: #200262 · Replies: 284 · Views: 870932 |
| Posted on: May 19 2013, 01:10 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Doug has seen the damaged VSTB wheels in person and I haven't, so he's in a better position than me to know if the anodizing is actually broken off or not. |
| Forum: MSL · Post Preview: #200259 · Replies: 284 · Views: 870932 |
| Posted on: May 19 2013, 01:08 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Given the level of damage observed so far on the rover wheels and the small distance traveled, if you linearly extrapolate future damage vs distance traveled, how far can the rover drive before a wheel fails? I would also assume the rover drives will be planned to avoid sharp rocks whenever possible? It's not really a linear process. The tire is one solid piece of aluminum. It would have to be ripped all the way across so it started unpeeling from the flexures before driving would be impeded. Like the viewgraphs I linked to earlier said, localized rupture in the tire was expected. We're talking about sharp pebbles, I don't think driving around them would be feasible. |
| Forum: MSL · Post Preview: #200258 · Replies: 284 · Views: 870932 |
| Posted on: May 19 2013, 01:00 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
I certainly don't know the coating or type of specific anodizing used, but anodizing in general is not a coating that can be "popped" off. Anodizing is an electrochemical process whereby the top layer of aluminum is converted to alumina (AlO2) -- http://en.wikipedia.org/wiki/Anodizing There are several types and they tend to produce different thicknesses of alumina. In my experience, you can get a thin layer to pop off if you work at it, but I suspect that these dents are just specular highlights off the intact anodizing, since the black anodizing is not very matte. |
| Forum: MSL · Post Preview: #200257 · Replies: 284 · Views: 870932 |
| Posted on: May 16 2013, 08:02 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
See slide 32 in http://trs-new.jpl.nasa.gov/dspace/bitstre...4/1/12-0690.pdf QUOTE Wheel cleats and surfaces thoroughly tested for odometry, wheel impact, functionality -- localized denting & rupture, ovalization permitted |
| Forum: MSL · Post Preview: #200198 · Replies: 284 · Views: 870932 |
| Posted on: May 16 2013, 03:06 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Could there be anything on Mars hard enough to make a narrow puncture through that much metal? I won't speculate on these images, but the wheels are pretty thin (I don't know what the actual number is) and the loads can be pretty high on a sharp rock. Aluminum isn't that hard. |
| Forum: MSL · Post Preview: #200188 · Replies: 284 · Views: 870932 |
| Posted on: May 16 2013, 03:03 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
If the rover is still roving, such reassurance is utterly redundant. That's a nice empirical observation. Somewhere in a review package I expect there's a detailed analysis of how the wheel was designed, with allowable levels of damage, predicted damage and margins. I haven't seen that package and if I had, I couldn't post the details anyway. So any assurance I could offer on this forum wouldn't really be fact-based, but I assume the designers had it under control. Over on nasaspaceflight.com someone proposed a drinking game based on how many times this comes up |
| Forum: MSL · Post Preview: #200187 · Replies: 284 · Views: 870932 |
| Posted on: May 6 2013, 02:31 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
It's easy to take shots at this admittedly sloppy writing, but I'm not sure that even sites like http://solar-center.stanford.edu/singing/singing.html do all that good a job of explaining how SOHO actually measures "sounds" from the Sun. Calling any periodic behavior a "sound" seems like be a source of some confusion. |
| Forum: Chit Chat · Post Preview: #200050 · Replies: 549 · Views: 459727 |
| Posted on: May 2 2013, 01:10 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
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| Forum: MSL · Post Preview: #200010 · Replies: 842 · Views: 467673 |
| Posted on: May 2 2013, 04:29 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Is it just inertia that keeps us using that expression? We've always talked about ground software and flight software. It's descriptive and unambiguous. It's hard to think of alternatives that would be better. It's also the same software that was flying the spacecraft on the way to Mars and during EDL. |
| Forum: MSL · Post Preview: #200004 · Replies: 842 · Views: 467673 |
| Posted on: May 1 2013, 12:21 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
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| Forum: MSL · Post Preview: #199976 · Replies: 842 · Views: 467673 |
| Posted on: Apr 23 2013, 06:21 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
I wonder why they treated the solar flux as a constant (441.1Wm2 representing a faint young sun) rather than treating it as a variable. Climatologists love the faint young sun paradox because it gives them an interesting problem to work on. They're not astrophysicists so they can't work on the possibility that the Standard Solar Model is wrong or incomplete. |
| Forum: Mars · Post Preview: #199856 · Replies: 10 · Views: 13927 |
| Posted on: Apr 22 2013, 02:34 AM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
Mike, one question that I had about this paper was that it takes as fact the notion that most of the observed sedimentary rocks postdate the valley networks... I am neither an expert nor a big believer in age dating by crater counting, especially on Mars where we have burial and exhumation and complex erosional processes to worry about. Certainly Malin and Edgett assign most of the sedimentary rocks to the Noachian; see the whole discussion of age relations starting on page 1929 of "Sedimentary Rocks of Early Mars" Science 290, December 2000. But I'm not convinced anyone really knows in detail. I reread Haberle ("Early Mars Climate Models", JGR 103 E12, November 1998) and it has plenty of "escape clauses" for how early Mars could have been warm enough to have large amounts of liquid water, so I think the motivation for a more exotic mechanism is not absolute. That said, the last few paragraphs of Malin and Edgett they advance a somewhat "Kite-like" hypothesis (before Kite did, obviously): QUOTE The second scenario is substantially more exotic and attempts to conceive a plausible but uniquely martian explanation for what is ob- served. In this model, modulation of atmospher- ic pressure by astronomical perturbations, com- bined with catastrophic modulation of sediment sources, gives rise to conditions recorded by the layered, massive, and thin mesa units. |
| Forum: Mars · Post Preview: #199845 · Replies: 10 · Views: 13927 |
| Posted on: Apr 20 2013, 09:10 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
True, but Mars morphology is not always Earthlike... From a purely terrestrial perspective Aeolis Mons is more like a surrealist painting than a geological construct. I'm not convinced that a lot of geomorphologists would agree with this statement. If the mound is an erosional remnant instead of being formed in place, I'm not sure it's that remarkable on its own. |
| Forum: Mars · Post Preview: #199838 · Replies: 10 · Views: 13927 |
| Posted on: Apr 20 2013, 04:05 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
The idea that the last liquid water on an increasingly airless Mars would have worked its geological magic under a covering of snow makes a lot of sense. The paper is well worth reading, but as it says in section 6.2, it really doesn't address the valley networks and alluvial fans. (It tries, but doesn't completely succeed to my taste.) As a general rule, explaining Earthlike morphology with non-Earthlike processes needs a high level of motivation. ("If it looks like a duck", etc.) IMHO, section 1 oversells that motivation in the case of early Mars, though I need to read Haberle 1998, which I hadn't recalled was so definitive. But as a jumping-off point for discussion, the paper is very good. |
| Forum: Mars · Post Preview: #199833 · Replies: 10 · Views: 13927 |
| Posted on: Apr 13 2013, 07:49 PM | |
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Senior Member ![]() ![]() ![]() ![]() Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 |
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| Forum: Past and Future · Post Preview: #199738 · Replies: 220 · Views: 288433 |
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