IPB

Welcome Guest ( Log In | Register )

5 Pages V  « < 3 4 5  
Reply to this topicStart new topic
Neptunian System Imaging
antipode
post Jul 19 2018, 07:26 AM
Post #61


Member
***

Group: Members
Posts: 238
Joined: 1-October 06
Member No.: 1206



Amazing image, although I hope the EELTs will do better (and faster than the next ice giant mission).

Although orbiters are badly needed to both, I wonder if cheaper New Horizons-like flybys might not be more likely
as long as there is suitable geometry for a subsequent large (spherical) TNO flyby after? So many are binaries you'd
get quite a lot of bang for the buck.

p
Go to the top of the page
 
+Quote Post
JRehling
post Jul 19 2018, 06:15 PM
Post #62


Senior Member
****

Group: Members
Posts: 2127
Joined: 20-April 05
Member No.: 321



Here's a state of the art image of Ganymede using the 5m Hale Telescope.

http://www.unmannedspaceflight.com/index.p...st&p=233427

The ELT (named changed from the previous E-ELT) will have 8 times the aperture, and Neptune is roughly 8 times more distant than Jupiter, so that indicates the resolution that will be possible for the Neptunian system and similarly distant objects such as Pluto. Of course, the ELT will not be dedicated to Neptune observations. I think we can safely say, however, that global Neptunian weather patterns can be tracked by other multi-meter telescopes from the ground and so the return-on-investment of Neptune missions decreases accordingly.

For fine detail of the planet and satellites, of course, there's no substitute for being there.

I think one of the best value propositions for Uranus/Neptune missions would be a flyby that targeted one of the larger TNOs and used the ice giants for a gravity assist on the way there. Four such missions could capture >75% coverage of selected satellites (obviously, Triton being one) and then provide an encounter of, potentially, New Horizons type value at Makemake, Haumea, etc. with great synergy in designing and manufacturing four identical craft with New Horizons legacy tech.

I don't see how a Uranus or Neptune orbiter could possibly jump the queue over many potential ambitions to closer targets of very high interest, Enceladus and Titan to name just two.
Go to the top of the page
 
+Quote Post
jccwrt
post Aug 26 2018, 06:29 PM
Post #63


Member
***

Group: Members
Posts: 264
Joined: 4-October 14
Member No.: 7273



A recreated view of the Neptune system as seen by Voyager 2 at approximately 1615 UT. I picked this time because Voyager made back-to-back observations of Neptune and Triton, so the appearance of these bodies closely approximates what a simultaneous view would have looked like.


Neptune and Triton - Voyager 2

I used a wide-angle OGV shot of Neptune and a narrow-angle GV observation of Triton. I recreated the view using a Neptune Viewer plot taken at the center of the Neptune observation, and then placed the reduced-size image of Triton in the appropriate positions. The slight difference in the direction that the crescent horns point is real - their position relative to the Sun was close enough that the phase angle was different from Voyager's point of view.

There is one improvement that I can think of. Neptune's remaining "major" moons should have been present in this scene as well, but I am not sure about their visibility to an observer at Voyager 2's location. Their small size and the position of the spacecraft suggest that they would only be a pixel or two across in the wide-angle camera and most of that surface would be in darkness. I am planning to look through some Neptune images taken a couple hours later where Galatea and Thalassa are present in the frame, which should help me determine if including them in this image would be appropriate.
Go to the top of the page
 
+Quote Post
jccwrt
post Jan 17 2019, 02:07 AM
Post #64


Member
***

Group: Members
Posts: 264
Joined: 4-October 14
Member No.: 7273



Working with some of my eclipse calculations from a few years back - I wanted to see if there were any interesting color sets of shadow transits at moderate resolution. I did find a decent set involving Despina's shadow early on August 24 through the WAC. Neptune itself is an OGV natural color image, but I have composited in the moons from several separate images. All three moons visible within this image are brightened by about 10x. (Naiad and Thalassa should both be theoretically visible but were below the detection limits with this exposure setting.)

Go to the top of the page
 
+Quote Post
MarcF
post Feb 21 2019, 02:21 PM
Post #65


Member
***

Group: Members
Posts: 215
Joined: 16-May 06
From: Geneva, Switzerland
Member No.: 773



Nice new article in Nature about the inner moons of Neptune
The latest discovered inner moon of Neptune has now a name : Hippocamp
https://www.skyandtelescope.com/astronomy-n...campaign=buffer

From the paper:
"Hippocamp orbits close to Proteus, the outermost and
largest of these moons, and the orbital semimajor axes of the two
moons differ by only ten per cent. Proteus has migrated outwards
because of tidal interactions with Neptune. Our results suggest that
Hippocamp is probably an ancient fragment of Proteus, providing
further support for the hypothesis that the inner Neptune system
has been shaped by numerous impacts."

Also, Naiad hadn't been seen since Voyager 2's flyby. Showlater's team did spot it but in a spot diametrically opposite where it should have been, based on the presumed orbit. Thalassa (92 km) proved less challenging but was still displaced 19 from its predicted orbital longitude. The team also reports that no other moons larger than 24 km likely lie within 200,000 km of Neptune or larger than 20 km farther out.

The ring/inner moons system of Uranus was known to be a very dynamic system. The same seems to be true with Neptune ring/inner moons system.
Regards,
Marc.
Go to the top of the page
 
+Quote Post

5 Pages V  « < 3 4 5
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 20th March 2019 - 07:49 PM
RULES AND GUIDELINES
Please read the Forum Rules and Guidelines before posting.

IMAGE COPYRIGHT
Images posted on UnmannedSpaceflight.com may be copyrighted. Do not reproduce without permission. Read here for further information on space images and 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 a project of the Planetary Society and is funded by donations from visitors and members. Help keep this forum up and running by contributing here.