Mercury Flyby 1 |
Mercury Flyby 1 |
Jan 16 2008, 11:00 AM
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#271
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Member Group: Members Posts: 568 Joined: 20-April 05 From: Silesia Member No.: 299 |
'n1ckdrake' - I think Astro0 meant 25 to 30 Kilobytes per hour. Correct Kilobytes. 25-30 Kilobytes per hour? Are you sure? Rather 25-30 Kilobytes per second. -------------------- Free software for planetary science (including Cassini Image Viewer).
http://members.tripod.com/petermasek/marinerall.html |
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Jan 16 2008, 11:08 AM
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#272
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IMG to PNG GOD Group: Moderator Posts: 2250 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
25-30 kilobits per second (kbps) seems likely. Downlink bandwidth is usually given as kbps and 25-30 kbps is comparable to various inner solar system spacecraft. It would be nice to know for sure the correct value though.
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Jan 16 2008, 11:12 AM
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#273
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
Even 25 kbps sounds like a rather low bandwidth for inner solar system standards. Granted, MESSENGER doesn't use a dish antenna, but still - Cassini can get over 100 kbps from 9 AU away.
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Jan 16 2008, 11:22 AM
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#274
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Senior Member Group: Members Posts: 1619 Joined: 12-February 06 From: Bergerac - FR Member No.: 678 |
What extraordinary times we're living
If you want, I have made a desktop version of the last pic Messenger send us. -------------------- |
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Jan 16 2008, 11:28 AM
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#275
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
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Jan 16 2008, 11:44 AM
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#276
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Senior Member Group: Members Posts: 3648 Joined: 1-October 05 From: Croatia Member No.: 523 |
I guess that's a Discovery class imposed weight limitation. It's expected that MESSENGER will, on average, get up to 80 full resolution images per day once in orbit. This is based on onboard compression speed and mission requirements (which I guess are greatly affected by available bandwidth).
It's remarkable how tight the point spread function of the wide angle camera is, it looks tighter than 1 pixel. In fact, it almost looks like it's causing some aliasing and the WAC images certainly don't need any sharpening applied like the NAC images do. WAC is a great context camera, one of the sharpest imagers I've seen; look at the sharpness of small craters near the terminator. Can't wait to see the color version of the above image. -------------------- |
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Guest_Oersted_* |
Jan 16 2008, 01:10 PM
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#277
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Guests |
Marvellous images: what a great age to live in!
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Jan 16 2008, 01:23 PM
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#278
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Senior Member Group: Members Posts: 3419 Joined: 9-February 04 From: Minneapolis, MN, USA Member No.: 15 |
OK -- 30 kilobits per second, I can see. At 30 kilobytes per hour, you would be getting about 210 kilobytes over seven hours, and even the jpeg'ed images we've already seen are larger than that. Each.
Unless there is some kind of uber-compression going on here of which I'm not aware, I would think it would be hard to fit 1,200 images into a file only 210 KB large. -the other Doug -------------------- The trouble ain't that there is too many fools, but that the lightning ain't distributed right. -Mark Twain
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Jan 16 2008, 01:55 PM
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#279
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Junior Member Group: Members Posts: 55 Joined: 1-May 06 From: Cincinnati, Ohio Member No.: 758 |
When I was a mere boy, Mariner 4 flew past Mars and sent it's fuzzy, smearing 22 photos of Mars back at the rate of 8 1/3 bits per second!!!! That makes 25 kilobits per hour sound high, but the effective bit rate is less than 7 bits per second... In this age of digital instant gratification waiting is not something we like to do.
I am really enjoying the "instant science" here. It reminds me of the Pioneer and Voyager flybys. :-) Rob |
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Jan 16 2008, 03:10 PM
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#280
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
Galileo made us forget how much the internet had advanced things, since it was often months before the data was on the ground.
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Jan 16 2008, 03:51 PM
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#281
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Member Group: Members Posts: 809 Joined: 11-March 04 Member No.: 56 |
Would anybody like to have some fun matching the new image to this old-style telescopic albedo map from the early 20th century?
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Jan 16 2008, 04:07 PM
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#282
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Solar System Cartographer Group: Members Posts: 10153 Joined: 5-April 05 From: Canada Member No.: 227 |
Good luck! Unfortunately, Antoniadi and all astronomers of the time thought Mercury was tidally locked to the sun. That's why his map shows just one side. It's really a composite of all 360 degrees compressed into 180. Every time Antoniadi looked at Mercury and what he saw didn't look the way he imagined it should, he thought clouds were interfering with his view - clouds on Mercury, I mean. A dark spot was hidden by hazes, or a bright spot was a thick cloud.
So this map can't be used as you suggest. When the rotation became known (from radar studies) a new map was compiled and used to redistribute placenames around the planet for the IAU. Rotational effects do make our views selective, so there is some relationship between Antoniadi's map and the later IAU map. But your question really should be applied to the IAU map. Incidentally, the original names of USGS map sheets are taken from the old albedo nomenclature. Caloris is in Liguria, if you need to know! Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke Maps for download (free PD: https://upload.wikimedia.org/wikipedia/comm...Cartography.pdf NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
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Jan 16 2008, 04:10 PM
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#283
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Member Group: Members Posts: 279 Joined: 19-August 07 Member No.: 3299 |
A quick questions.
I doubt that Messenger will not take zoomed pictures like MRO? I am not able to get the value of image resolution (m/pixel) of narrow and wide angle imagers of Mercury Dual Imaging System. I am interested if MDIS will be able to take an even more detailed pictures of landforms and surface features than the recently posted ones. Is the Mercurian landform regolith alike to Moon since Solar energetic particles bombard its surface even stronger and more than on the Moon? This would lead that the Mercurian surface would very dusty like Moon or Mars? |
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Jan 16 2008, 04:19 PM
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#284
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Founder Group: Chairman Posts: 14432 Joined: 8-February 04 Member No.: 1 |
This single image was picked to be downlinked as it was the highest resolution image image that included the whole planet. It's about 3km/pixel
Now - MDIS will not reach HiRISE resolutions. But the highest resolution images from this flyby will be about 120m/pixel - so about 25 times better than this first returned image. http://messenger.jhuapl.edu/encounters/ind...×tep=7 Doug |
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Jan 16 2008, 04:50 PM
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#285
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Newbie Group: Members Posts: 5 Joined: 15-January 08 Member No.: 4013 |
That is indeed, and it's replacing my current wallpaper (an Apollo montage), it'll be interesting to see just how many people mistake this for the Moon (and believe me it will happen). I don't know if I'm quite ready to replace my Spitzer IR montage of the center of our galaxy just yet. So, will we have to wait until 2011 for the "good stuff"? |
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