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Unmanned Spaceflight.com > All posts by a member| Posted on: May 11 2018, 11:06 PM | |
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Senior Member  Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497 
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QUOTE (Explorer1 @ May 11 2018, 01:16 PM)  Obviously some benefits to the Dragonfly Titan proposal in terms of getting experience with autonomous rotor-driven spacecraft... I think you overestimate the level of cooperation and information flow between JPL and APL, even if the two vehicles had much in common other than having rotors. |
| Forum: Perseverance- Mars 2020 Rover · Post Preview: #239367 · Replies: 343 · Views: 431531 |
| Posted on: May 10 2018, 09:25 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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Press kit says Nov. 26, 2018, about noon PST (3 p.m. EST; 20:00 UTC). |
| Forum: InSight · Post Preview: #239353 · Replies: 129 · Views: 147599 |
| Posted on: May 6 2018, 04:44 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Explorer1 @ May 6 2018, 08:04 AM) I am wondering what the issue is with the batteries remaining fully charged; I've heard about this before, but does anyone have more details? http://batteryuniversity.com/learn/article...based_batteries Your battery would last longest if you constantly maintained it at somewhere between 50% and 75% of capacity. Of course you want to discharge it sometimes since otherwise there's not much point in having a battery. |
| Forum: Opportunity · Post Preview: #239317 · Replies: 37 · Views: 113021 |
| Posted on: May 3 2018, 07:55 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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| Forum: Mars · Post Preview: #239281 · Replies: 5 · Views: 20033 |
| Posted on: Apr 29 2018, 08:35 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (peter.neaum @ Apr 27 2018, 01:59 PM) My thought was 'what wear is there in a brushless motor?' The bearings and gear teeth still see wear in a brushless motor. Predicting the lifetime of any mechanical system, or any system at all for that matter, is a bit of a black art. |
| Forum: Opportunity · Post Preview: #239247 · Replies: 37 · Views: 113021 |
| Posted on: Apr 29 2018, 08:30 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (James Sorenson @ Apr 29 2018, 09:50 AM) Was there ever testing done on this for the MAX-C concept? As far as I know MAX-C was a series of viewgraphs "designed" by scientists and systems people. Engineers generally come in and make things work only after the mission is selected. Let's put this speculative discussion somewhere else as it's off-topic for MER. The rover after M2020 will likely resemble MER only in that it will have wheels and drive around.  |
| Forum: Opportunity · Post Preview: #239246 · Replies: 37 · Views: 113021 |
| Posted on: Apr 4 2018, 10:04 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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The second set of PJ12 images, including the GRS images, are now on missionjuno. The rest of the images continue to come down slowly. |
| Forum: Juno · Post Preview: #239015 · Replies: 79 · Views: 84835 |
| Posted on: Apr 4 2018, 05:45 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Sean @ Apr 4 2018, 09:00 AM) I wondered what size 'Anticyclonic White Oval WS-4' was... This can be determined directly from the Junocam image to some level of accuracy. The metadata says the s/c altitude for this image was 8681.9 km, so the resolution at nadir is 8681.9*673e-6 = 5.8 km/pixel. WS-4 is about 900 pixels across on its long axis in the raw frames, so that's 5220 km (ignoring perspective effects.) |
| Forum: Juno · Post Preview: #239012 · Replies: 79 · Views: 84835 |
| Posted on: Apr 4 2018, 03:03 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Apr 3 2018, 11:02 PM) If anyone answers this for Philip, can you also post which spice kernels were loaded to make the determination. Using juno_pred_orbit.bsp at webgeocalc, the distance was about 550,000 km. |
| Forum: Juno · Post Preview: #239008 · Replies: 79 · Views: 84835 |
| Posted on: Apr 3 2018, 12:35 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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First batch of PJ12 images are available on missionjuno. It's taking a while since most of the DSN passes are only 40 Kbps. |
| Forum: Juno · Post Preview: #238989 · Replies: 79 · Views: 84835 |
| Posted on: Mar 24 2018, 03:55 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Mar 23 2018, 09:21 PM) My modeling is currently estimating a value of 0.001032 sec for the adjustment. Well, I can't say that's impossible, but it's about 30x larger than the largest clock error I would expect given the specification of the clock oscillator. An error in interframe delay and/or spin rate would lead to increasing downspin errors over the course of a full image acquisition. Our star and galilean satellite imaging analyses don't show those to my eye (if I'm doing the math right the error you state would build up to 82*0.000032*371 or almost a second of error over a full spin, which would be easily noticable) but I don't claim to know for sure. |
| Forum: Juno · Post Preview: #238919 · Replies: 183 · Views: 181452 |
| Posted on: Mar 24 2018, 01:22 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Mar 23 2018, 04:44 PM) Thanks Mike. Can you make an original resolution version of the image available. I guess, but it's just eye candy without practical benefit, right? QUOTE Also, do you know how accurate the .001s adjusted INTERFRAME_DELAY is? I've only seen the values of the INTERFRAME_DELAY and adjustment given to 1ms of precision, but I believe the accuracy is significantly better than that. If I understand your question, it's not. The delay is commanded in multiples of 20000 cycles of a 20 MHz clock, and the 1 msec offset was caused by an off-by-one misunderstanding in the commanding of the counter. So to the accuracy of the clock oscillator, which we don't know anything about other than it's within 20 ppm or so, the adjustment really is 1.0000 msec. It's probably slightly different, but we have no internal way of assessing that. |
| Forum: Juno · Post Preview: #238915 · Replies: 183 · Views: 181452 |
| Posted on: Mar 23 2018, 06:11 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Mar 18 2018, 08:38 AM) Mike, Can you release to public domain the photo of the sensor and filters that is Figure 12 in "Junocam: Juno’s Outreach Camera"? The paper is open access: "This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited." |
| Forum: Juno · Post Preview: #238913 · Replies: 183 · Views: 181452 |
| Posted on: Mar 21 2018, 11:29 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Floyd @ Mar 21 2018, 02:40 PM) When I see these images I always wonder about the trade off of putting a super telephoto camera on a rover. FWIW, Supercam on M2020 has MSL RMI-like resolution but will be in color; I don't know the specifics but they're probably out there somewhere. There's a lot more color capability on M2020; we did it first, now everybody is doing it. |
| Forum: MSL · Post Preview: #238904 · Replies: 685 · Views: 498516 |
| Posted on: Mar 6 2018, 03:06 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Bjorn Jonsson @ Mar 5 2018, 03:22 PM) Regarding C kernels, I always use orientation data from the C kernel for every R/G/B set of framelets (typically 25-40 sets per image) and I also do this for the spacecraft position. This is the only method I would have imagined would be adequate without a lot of manual tweaking, and it's the way the MSSS processing works. As far as I can tell from reading Brian's Mathematica code (I don't have Mathematica and the raw ASCII is not the easiest thing to read) he isn't using the C kernel data and he only uses the spacecraft position at the beginning of imaging, but his results are very good so perhaps this doesn't matter in most cases. As for the expected errors, using our parameters the position error of the galilean satellites on orbit 1 had standard deviations of about 1 in X and about 2.8 in Y. I attribute the higher Y error to timing slop, but we could have residual geometric distortion error because the satellites were probably near the optic axis where distortions are lower. For obscure reasons, our own standard processing isn't using our updated parameters yet, though. |
| Forum: Juno · Post Preview: #238782 · Replies: 183 · Views: 181452 |
| Posted on: Mar 1 2018, 03:46 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Gerald @ Mar 1 2018, 04:08 AM) During the first few hours after a s/c op, Juno may oscillate a bit... True. If you're using the C kernel, any oscillation should be captured in the kernel. If you're not using the C kernel, then all bets are off. I still find it hard to tell in this whole exchange if people are using the C kernel, and if so, how and when. If there are errors in the angular offsets for Junocam in the I kernel and frames kernel, or if there's spacecraft motion not being captured in the C kernel, I'd like to know about those problems so they can be fixed. |
| Forum: Juno · Post Preview: #238734 · Replies: 183 · Views: 181452 |
| Posted on: Feb 28 2018, 06:44 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (JRehling @ Feb 27 2018, 08:16 PM) The Galileo Probe had no camera... it would have been a very expensive instrument needing a lot of bandwidth during a very short time window. There was actually a proposal for a low-cost camera that fit within the data allocation for the Galileo probe, but it wasn't selected. |
| Forum: Juno · Post Preview: #238718 · Replies: 38 · Views: 60838 |
| Posted on: Feb 27 2018, 03:32 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Gerald @ Feb 26 2018, 03:27 PM) For processing close-up images, or for rendering illumination-adjusted images, I'm using sets of 8 dumped (saved) trajectory position files with different frame settings, that implicitely contain all relevant kernel informations including CK. I guess I assumed since you independently computed the spin rate and axis from the marble images that your position information was in an inertial or Jupiter-fixed frame and didn't include any knowledge of spacecraft orientation, but I guess if you have position in a spacecraft-fixed frame then the orientation is convolved into that. That aside, I've tried to document the standard processing flow in the Junocam I kernel. There's some evidence that this works to 1-2 pixel accuracy, and I don't think one can expect anything better than that without doing limb fits or some kind of ad hoc color registration. |
| Forum: Juno · Post Preview: #238709 · Replies: 183 · Views: 181452 |
| Posted on: Feb 26 2018, 10:36 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Gerald @ Feb 26 2018, 02:25 PM) Inferred means inferred from raw JunoCam images. Assumptions can be from any source, including SPICE, or just guessed, or arbitrary. I'm not sure that answers the original question. To the extent that I understand Gerald's processing flow, he uses the spacecraft position data (SPK file) at least in some cases, but never the orientation data (CK). |
| Forum: Juno · Post Preview: #238702 · Replies: 183 · Views: 181452 |
| Posted on: Feb 26 2018, 03:37 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Feb 26 2018, 12:22 AM) So, I was curious how much the spin axis has changed The spacecraft sends down its orientation as determined by the star trackers at fairly high resolution and these data are assembled into the C kernels, so it's not like this is some big mystery if you are using SPICE. QUOTE I’ve wondered about is the effect of onboard compression... Certainly there is a small effect, especially for the high compression factors we were using for star imaging in cruise. But I wouldn't say it's any more significant than other sources of error, like motion blur from spacecraft nutation. We didn't even bother to compute centroids for our analysis, we just used the eyeball location of stars. As I've said before, expecting subpixel registration without any manual adjustment steps is probably not achievable. |
| Forum: Juno · Post Preview: #238696 · Replies: 183 · Views: 181452 |
| Posted on: Feb 24 2018, 03:29 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Brian Swift @ Feb 23 2018, 12:46 PM) Anyone have suggestions on how I can determine the rotation (and tilt) of the Junocam CCD relative to Juno spin axis? If you use SPICE, all of this is managed for you by the frames system. If you have a vector in the JUNO_JUNOCAM coordinate system (which is formed by the camera boresight and the CCD line and sample directions) and you want to transform it into some other system, either inertial or not, you can just call pxform to get a rotation matrix for a particular time, and then call mxv to transform a vector from one coordinate system to another. The raw values for what these transforms consist of are in the "frames kernel" https://naif.jpl.nasa.gov/pub/naif/JUNO/ker.../fk/juno_v12.tf but all you need to do when using SPICE is load this kernel, and the software does the rest. As Gerald says, these angles are pretty small, so for many purposes you can just assume that Junocam is perfectly pointed along the spacecraft's -X axis. You don't need to understand mathematically how a rotation matrix or matrix-vector multiplication work to use SPICE effectively, although it doesn't hurt. |
| Forum: Juno · Post Preview: #238678 · Replies: 183 · Views: 181452 |
| Posted on: Feb 9 2018, 06:49 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Explorer1 @ Feb 8 2018, 08:44 PM) Gosh, that's one bright cloud pattern at #13 (and near the edge in #12)! It almost looks overexposed... It's bright but not that bright in the MSSS processed version, so I'm thinking this is an artifact of Gerald's processing. |
| Forum: Juno · Post Preview: #238561 · Replies: 57 · Views: 67819 |
| Posted on: Feb 3 2018, 03:29 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Explorer1 @ Feb 2 2018, 06:33 PM) I can't remember. the rings have already been caught with Junocam, correct? Yes, barely. https://www.missionjuno.swri.edu/junocam/processing?id=368 It's not the perijoves that are going into shadow, it's the approach side of the planet roughly 180 degrees from perijove. At any rate I don't think the geometry is very favorable for seeing the rings, else they might have been visible in the PJ10 images. Junocam was never intended to look for things that were very dark. |
| Forum: Juno · Post Preview: #238516 · Replies: 71 · Views: 87398 |
| Posted on: Feb 3 2018, 01:54 AM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Gsnorgathon @ Feb 2 2018, 04:36 PM) Are those Jupiter's rings at the top in the last frame? Those are stray light artifacts. In fact, not to be a buzzkill, but all of it could be stray light artifacts. |
| Forum: Juno · Post Preview: #238514 · Replies: 71 · Views: 87398 |
| Posted on: Jan 31 2018, 09:11 PM | |
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Senior Member Group: Members Posts: 2559 Joined: 13-September 05 Member No.: 497
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QUOTE (Ant103 @ Jan 30 2018, 03:33 PM) Actually, there was a Mastcam mosaic of the sky, near and on the zenith conducted by Curiosity on Sol 101. Looks like there was one survey done on sol 100 at around noon, and then another on sol 101 in the late afternoon. All of these images were autoexposed but the exposure times can be pulled out of the PDS index file https://pds-imaging.jpl.nasa.gov/data/msl/M...EX/EDRINDEX.TAB . (Second column below.) Of course, to be really quantitative one would have to linearize the square-root images. CODE "0100ML0004900050102961E01_XXXX.LBL" 1.0 "0 " "Sol-00100M11:58:10.077 " "0100ML0004930000102962E01_XXXX.LBL" 4.0 "0 " "Sol-00100M11:59:11.392 " "0100ML0004930010102963E01_XXXX.LBL" 5.0 "0 " "Sol-00100M11:59:25.017 " "0100ML0004930020102964E01_XXXX.LBL" 5.0 "0 " "Sol-00100M11:59:38.643 " "0100ML0004930030102965E01_XXXX.LBL" 2.5 "0 " "Sol-00100M12:00:10.760 " "0100ML0004930040102966E01_XXXX.LBL" 2.8 "0 " "Sol-00100M12:01:16.941 " "0100ML0004930050102967E01_XXXX.LBL" 5.5 "0 " "Sol-00100M12:01:35.433 " "0100ML0004930060102968E01_XXXX.LBL" 6.9 "0 " "Sol-00100M12:01:51.978 " "0100ML0004930070102969E01_XXXX.LBL" 6.9 "0 " "Sol-00100M12:02:05.604 " "0100ML0004930080102970E01_XXXX.LBL" 5.6 "0 " "Sol-00100M12:02:21.176 " "0100ML0004930090102971E01_XXXX.LBL" 7.4 "0 " "Sol-00100M12:02:38.695 " "0101ML0006740000102999E01_XXXX.LBL" 6.4 "0 " "Sol-00101M15:40:03.764 " "0101ML0006740010103000E01_XXXX.LBL" 3.5 "0 " "Sol-00101M15:40:55.347 " "0101ML0006740020103001E01_XXXX.LBL" 5.7 "0 " "Sol-00101M15:41:15.785 " "0101ML0006740030103002E01_XXXX.LBL" 7.6 "0 " "Sol-00101M15:41:31.357 " "0101ML0006740040103003E01_XXXX.LBL" 9.0 "0 " "Sol-00101M15:41:47.902 " "0101ML0006740050103004E01_XXXX.LBL" 10.1 "0 " "Sol-00101M15:42:04.447 " "0101ML0006740060103005E01_XXXX.LBL" 10.1 "0 " "Sol-00101M15:42:19.046 " "0101ML0006740070103006E01_XXXX.LBL" 10.1 "0 " "Sol-00101M15:42:34.618 " "0101ML0006740080103007E01_XXXX.LBL" 11.3 "0 " "Sol-00101M15:42:50.190 " "0101ML0006740090103008E01_XXXX.LBL" 13.6 "0 " "Sol-00101M15:43:05.762 " "0101ML0006740100103009E01_XXXX.LBL" 15.9 "0 " "Sol-00101M15:43:21.335 " "0101ML0006740110103010E01_XXXX.LBL" 17.7 "0 " "Sol-00101M15:43:36.907 " "0101ML0006740120103011E01_XXXX.LBL" 17.7 "0 " "Sol-00101M15:43:51.505 " "0101ML0006740130103012E01_XXXX.LBL" 13.9 "0 " "Sol-00101M15:44:15.837 " "0101ML0006740140103013E01_XXXX.LBL" 13.9 "0 " "Sol-00101M15:44:29.462 " "0101ML0006740150103014E01_XXXX.LBL" 13.9 "0 " "Sol-00101M15:44:43.088 " "0101ML0006740160103015E01_XXXX.LBL" 11.1 "0 " "Sol-00101M15:44:58.660 " "0101ML0006740170103016E01_XXXX.LBL" 19.7 "0 " "Sol-00101M15:45:19.098 " "0101ML0006740180103017E01_XXXX.LBL" 13.6 "0 " "Sol-00101M15:45:48.296 " "0101ML0006740190103018E01_XXXX.LBL" 16.2 "0 " "Sol-00101M15:46:13.600 " "0101ML0006740200103019E01_XXXX.LBL" 16.2 "0 " "Sol-00101M15:46:27.226 " "0101ML0006740210103020E01_XXXX.LBL" 16.2 "0 " "Sol-00101M15:46:43.771 " "0101ML0006740220103021E01_XXXX.LBL" 14.0 "0 " "Sol-00101M15:46:59.343 " "0101MR0004910040104491E01_XXXX.LBL" 0.5 "0 " "Sol-00101M15:49:01.000 " "0101ML0004910050103023E01_XXXX.LBL" 1.0 "0 " "Sol-00101M15:49:33.117 " |
| Forum: Mars · Post Preview: #238484 · Replies: 90 · Views: 255133 |
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