New Horizons Pluto System Final Approach, 28 Jun-13 Jul 15 |
New Horizons Pluto System Final Approach, 28 Jun-13 Jul 15 |
Jun 29 2015, 12:34 PM
Post
#16
|
|
Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
The SOFIA telescope is observing Pluto occultating a star today; does anyone know if results of this will be available before the Pluto encounter? It would be interesting to know if Pluto's atmosphere is still growing, remains stable or has started shrinking.
Maybe a little fun; is there a poll facility on the site? We could puree our collective brains into a jar and come up with the official unofficial UMSF list of predictions. Another option would be to have a separate thread where members are invited to post their predictions for the Pluto system. I think it could be fun. -------------------- |
|
|
Jun 29 2015, 01:22 PM
Post
#17
|
|
Member Group: Members Posts: 244 Joined: 2-March 15 Member No.: 7408 |
@fred_76 At what point do those formulae cease being reasonable approximations? You have an asymptote to infinity on the day of the flyby.
|
|
|
Jun 29 2015, 04:10 PM
Post
#18
|
|
Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
-------------------- |
|
|
Jun 29 2015, 04:17 PM
Post
#19
|
|
Junior Member Group: Members Posts: 47 Joined: 21-June 15 Member No.: 7518 |
@fred_76 At what point do those formulae cease being reasonable approximations? You have an asymptote to infinity on the day of the flyby. In fact there are two things : 1) the approximation of the inverse tangente atan x ~ x because the diameter of the planet by far smaller than its distance from NH, 2) the asymptote you talk about In practice, those formulae are quite valid until a pair of hours before "contact" as NH travels at 46500 km/h which is >> planets dia. -------------------- Astronopithecus normandimensis nephophobis
|
|
|
Jun 29 2015, 04:40 PM
Post
#20
|
|
Member Group: Members Posts: 423 Joined: 13-November 14 From: Norway Member No.: 7310 |
Trying to compare one of the raw images from today (rotated only first from left, rotated and interpolated scaling second from left) with two deconvoluted releases from 8 June and 15 June (respectively):
-------------------- |
|
|
Jun 29 2015, 05:06 PM
Post
#21
|
|
Junior Member Group: Members Posts: 47 Joined: 21-June 15 Member No.: 7518 |
-------------------- Astronopithecus normandimensis nephophobis
|
|
|
Jun 29 2015, 05:42 PM
Post
#22
|
|
Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Thanks, fred_76. This is a good way to convey the progression.
It's particularly poignant to see that 3-days-out image, because that's the best view we'll get of the anti-encounter hemisphere (AEH). However, I'll point out that the Moon is about 1.5x the size of Pluto, so while Pluto will appear that *size*, we'll see Pluto at 1.5x the resolution that those Moon photos show. Consequently, we'll see the AEHs of Pluto and Charon at the same resolution as your left 2-days-out image of the Moon. It's quite evident there that Tycho is a crater and one could surmise that Copernicus is. Otherwise, one could interpret the features in comparison to the better imagery of the other hemisphere, but on its own, it's still quite murky. The spectral imaging will add a lot, so that units on the AEH can be identified as likely similar to corresponding features on the encounter hemisphere. The Charon-shine imagery may fill that in wonderfully, though, and even more important, give us a look at the winter pole that won't otherwise be seen at all. The data set will basically be a tale of three Plutos: The encounter hemisphere, the anti-encounter daylight "hemi"sphere, and the winter pole. Similar for Charon, but we will only see its winter pole in Plutoshine from 3 days out, so we'll only get albedo/spectral information at very low resolution. On the other hand, Plutoshine is 4x brighter than Charonshine. As a reminder of "shine" imagery, here's Iapetus in Saturnshine. http://www.nasa.gov/mission_pages/cassini/...a/pia06168.html Saturn is, of course, a hell of a lot bigger and brighter than Pluto or Charon, but it's also 200 times farther from Iapetus than Charon is from Pluto, so Charon occupies ~2x the area in Pluto's sky that Saturn occupies in Iapetus'. So Charonshine on Pluto is only a few times dimmer than Saturnshine on Iapetus. |
|
|
Jun 29 2015, 07:10 PM
Post
#23
|
|
Junior Member Group: Members Posts: 88 Joined: 8-May 14 Member No.: 7185 |
I was born the same year Voyager visited Neptune, so this is the first of this sort of brand-new-world flyby* in my lifetime. It's super exciting! So you won't remember how we saw Neptune on rasterized photos in the newspaper. Earth has changed a lot since those summer days of 1989, amazingly by now letting all of us have a front-row seat to, and be part of, space exploration. Thanks UMSF! |
|
|
Jun 29 2015, 07:17 PM
Post
#24
|
|
Junior Member Group: Members Posts: 47 Joined: 21-June 15 Member No.: 7518 |
@JRehling : I Know the moon is bigger than Pluto, therefore I redimensionned it's image so that it has the same size as Pluto, when views from the same distance.
Now, for sure, as Pluto is certainly not made from the same materials as Moon, it's aspect will be different. -------------------- Astronopithecus normandimensis nephophobis
|
|
|
Jun 29 2015, 07:53 PM
Post
#25
|
|
Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Ah, sorry, Fred - I misread! My fault. And I'm doubly sorry, because that means the resolution will be 2/3 of what I'd thought.
The Moon seems, to me, to be unusually hard to interpret in its full phase. A lot of worlds, like Io, seem to look pretty good when full, but the Moon becomes a smear of maria, highlands, and rays. I hope Pluto is easier to make sense of in those distant, full images. |
|
|
Jun 29 2015, 09:13 PM
Post
#26
|
|
Solar System Cartographer Group: Members Posts: 10149 Joined: 5-April 05 From: Canada Member No.: 227 |
Io may look pretty good when full... but it sure wasn't easy to interpret!
I think the difficulty in interpreting the Moon at small phase angles (full or nearly so) is repeated for all worlds, notably in recent times Ceres and now Pluto. When Ceres looked twice as detailed as Pluto does today, we had interpretations of giant rifts and canyons on this very forum. Only resolution saves us. Phil -------------------- ... because the Solar System ain't gonna map itself.
Also to be found posting similar content on https://mastodon.social/@PhilStooke NOTE: everything created by me which I post on UMSF is considered to be in the public domain (NOT CC, public domain) |
|
|
Jun 29 2015, 09:39 PM
Post
#27
|
||||
IMG to PNG GOD Group: Moderator Posts: 2250 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Here are the 2015-06-29 05:03 images. This is a stack of three images enlarged by a factor of 4. Two images were also obtained 6 minutes earlier that I could have added to the stack but the resolution is now probably high enough for Charon's changing position relative to Pluto to possibly have become a minor problem without correcting for it (but I notice that machi used them successfully). This image is also a 'milestone' of sorts because the size of Pluto (and the distance in pixels between Pluto and Charon) is now so big that from now on I will probably post images enlarged by a factor of 3 (or smaller) instead of 4.
And this is Pluto with a lat/lon grid: This reveals that the pole may be close to the center of terrain that is slightly darker than the terrain farther from the pole. This is a somewhat tentative result though. Charon's shape looks slightly irregular here (and also in machi's version), probably for the same reasons that Pluto looked slightly irregular at lower resolution (Pluto now appears perfectly spherical). |
|||
|
||||
Jun 29 2015, 09:56 PM
Post
#28
|
|
Member Group: Members Posts: 796 Joined: 27-February 08 From: Heart of Europe Member No.: 4057 |
Here is slightly improved version. It's now made from 5 stacked images (previous was made from 4) and it's corrected for Charon's motion so Charon is now sharper.
BTW, darker area around Pluto's pole is almost certainly real feature because it's visible also in previous set from 28. June. -------------------- |
|
|
Jun 29 2015, 10:41 PM
Post
#29
|
|
Junior Member Group: Members Posts: 95 Joined: 5-September 07 Member No.: 3662 |
These last few images remind me of Titan, sans atmosphere.
|
|
|
Jun 30 2015, 12:11 AM
Post
#30
|
|
Member Group: Members Posts: 120 Joined: 26-May 15 From: Rome - Italy Member No.: 7482 |
|
|
|
Lo-Fi Version | Time is now: 23rd April 2024 - 11:40 AM |
RULES AND GUIDELINES Please read the Forum Rules and Guidelines before posting. IMAGE COPYRIGHT |
OPINIONS AND MODERATION Opinions expressed on UnmannedSpaceflight.com are those of the individual posters and do not necessarily reflect the opinions of UnmannedSpaceflight.com or The Planetary Society. The all-volunteer UnmannedSpaceflight.com moderation team is wholly independent of The Planetary Society. The Planetary Society has no influence over decisions made by the UnmannedSpaceflight.com moderators. |
SUPPORT THE FORUM Unmannedspaceflight.com is funded by the Planetary Society. Please consider supporting our work and many other projects by donating to the Society or becoming a member. |