IPB

Welcome Guest ( Log In | Register )

6 Pages V   1 2 3 > »   
Reply to this topicStart new topic
Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene, Also distant Iapetus
elakdawalla
post Feb 20 2010, 04:29 AM
Post #1


Bloggette par Excellence
****

Group: Admin
Posts: 4474
Joined: 4-August 05
From: Pasadena, CA, USA, Earth
Member No.: 454



Holy moly are these back-to-back flybys of Rhea and Helene going to ROCK!!!! Jason's Rev 127 looking ahead article has all the details. Wispy terrain high-res mosaic -- close look at putative impact sites of former ring particles -- MIMI attempt to confirm presence of Rhea ring -- Imaging of pretty much all of Helene using Saturnshine to illuminate sub-Saturn hemisphere on approach, sunshine on anti-Saturn hemisphere on departure -- departure shots will be against Saturn as a backdrop -- C/A shots will use skeet shoot technique derived for Encelauds -- etc. etc. --

I can't wait!! Thanks Jason for the preview!!!


--------------------
My blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
volcanopele
post Feb 20 2010, 04:33 AM
Post #2


Senior Member
****

Group: Moderator
Posts: 2864
Joined: 11-February 04
From: Tucson, AZ
Member No.: 23



The CICLOPS Looking Ahead article for Rev127 (February 22-March 12) is now online, detailing the upcoming targeted flybys of Rhea and the trojan moon, Helene. In the case of Rhea, Cassini will fly within 100 km of the surface in order to confirm the presence of a set of narrow rings at that satellite. Images will be acquired of portions of the trailing hemisphere wispy terrain and the equator.

However, the flyby I am looking forward to the most is that of Helene on March 3 @ 13:41 UTC, with an altitude of 1,817 km. In preparation of this encounter, I have created an animation in Celestia showing the views of Helene from the ISS narrow-angle camera (missing some on the third trigger, since there were 48...and I'm tired):

Attached Image


To give you an idea of what Cassini has seen of Helene before:

Rev094 (November 25, 2008): http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=174939
Rev048 (July 20, 2007): http://saturn.jpl.nasa.gov/photos/raw/rawi...?imageID=116643
Rev027 (August 17, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawi...m?imageID=80845
Rev027 (August 17, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawi...m?imageID=80858
Rev021 (February 25, 2006): http://saturn.jpl.nasa.gov/photos/raw/rawi...m?imageID=64363


--------------------
&@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io
Go to the top of the page
 
+Quote Post
jasedm
post Feb 21 2010, 08:28 AM
Post #3


Member
***

Group: Members
Posts: 513
Joined: 22-January 06
Member No.: 655



I'm loving the ring-plane orbits with all these icy moon/rock encounters - lots more to come in the next few months. Thanks VP for the detail included in the looking ahead articles - always very informative, and appetite-whetting.
I must admit I'm a little surprised that that the the 'skeet-shoot' technique is being employed at Helene, but delighted nonetheless - it'll be very intriguing to see how 'smooth' the moon is at a few tens of metres resolution.
Go to the top of the page
 
+Quote Post
TritonAntares
post Feb 21 2010, 11:23 AM
Post #4


Member
***

Group: Members
Posts: 267
Joined: 28-September 05
From: Orion arm
Member No.: 516



Hi,

just to mentioned:
QUOTE
Cassini's ISS camera starts its observations for Rev127 the day after apoapse by taking images of Iapetus, 1.53 million kilometers (0.95 million miles) away.
During this distant observation, ISS will observe the southern, sub-Saturn hemisphere of Iapetus.
Over the next four days, ISS will take four more multi-spectral observations of Iapetus,
with the distance to the satellite ranging from 1.55 to 1.92 million kilometers (0.97 to 1.12 million miles) away.

As there won't be any more close encounters of this outer large saturnian satellite, these far imagings are the only opportunities to get some further informations, e.g. the north/south pole and hopefully the region around the 'Snowman'.
Any information of other - probably closer - encounters until 2017 available ?

Thanks & Bye.
Go to the top of the page
 
+Quote Post
Floyd
post Feb 21 2010, 02:15 PM
Post #5


Member
***

Group: Members
Posts: 627
Joined: 4-September 06
From: Boston
Member No.: 1102



I think not. A search of the SM-7_all.doc (posted here on UMSF somewhere) did not have the word Iapetus. If I recall correctly, it would have taken too much fuel to get into that orbit. If you go to the Cassini site, click Mission Overview, then Saturn Tour Dates. About 10 lines down on that page is a link Click here for a more complete list of the planned tour dates in 2010. From there you can get to activities for each remaining year of the mission.


--------------------
Floyd
Go to the top of the page
 
+Quote Post
belleraphon1
post Feb 23 2010, 01:06 AM
Post #6


Member
***

Group: Members
Posts: 733
Joined: 29-December 05
From: NE Oh, USA
Member No.: 627



Looking forward to this one as well.

If Helene is like Calypso, be great to get high resolution of 'striated' terrain. Plus the Rhea "ring" impactors.

Glorious!!!

Craig
Go to the top of the page
 
+Quote Post
tasp
post Feb 23 2010, 03:38 AM
Post #7


Member
***

Group: Members
Posts: 885
Joined: 30-January 05
Member No.: 162



Do we get some close ups of the intriguing equatorial stains ??

I am greatly interested in the 'stuff' orbiting Rhea too. Is it organized more like the asteroid belt (variety of inclinations and eccentricities), or more like the Saturnian rings (more planar and circular orbits)? And perhaps we can pin down the periods of the orbiting 'stuff' and see if there is a correlation to the Rhean period about Saturn.

Also, is more material within or outside the Rhean Roche limit . . . .
Go to the top of the page
 
+Quote Post
DrShank
post Feb 25 2010, 06:31 PM
Post #8


Member
***

Group: Members
Posts: 161
Joined: 6-March 07
From: texas
Member No.: 1828



here are some nice perspective views of Rhea, target of the 100km pass next week.
they are based on stereo imaging of these regions acquired back in 2008. The first shows the western half
of the 6 km deep and 370 km wide Tirawa impact basin. The second shows the now
infamous blue equatorial streaks attributed to impact of Rhea's ring on to the surface. The frames
are from two Rhea flyover videos (too large to upload here) now on youtube (www.youtube.com/galsat400).
The Blue Streak movie shows one of these streaks lying across the top of a battered topographic ridge,
a common occurrence for these features consistent with a ring origin. The paper describing these
and the other Saturn ice moon color features has now been submitted for publication!

more details at http://stereomoons.blogspot.com
and http://www.youtube.com/galsat400
Attached thumbnail(s)
Attached Image
Attached Image
 


--------------------
Go to the top of the page
 
+Quote Post
TritonAntares
post Feb 25 2010, 10:53 PM
Post #9


Member
***

Group: Members
Posts: 267
Joined: 28-September 05
From: Orion arm
Member No.: 516



So,
about 75 images are online.

Here a quickout:
Attached Image

Distance: 1470377 km
Date: 2010-02-21

Nice but distant view of the snowman.

Btw., I thought about some unlisted encounters like this one, when Cassini is near apoapse, roughly 2.4 million kilometers away from Saturn.
From time to time the spacecraft gets in the vicinity of this outer large saturnian satellite.
May be one of the members is able to calculate the closest encounters until 2017 ?

Bye.
Go to the top of the page
 
+Quote Post
Adam Hurcewicz
post Feb 26 2010, 12:54 AM
Post #10


Junior Member
**

Group: Members
Posts: 71
Joined: 29-January 10
From: Poland
Member No.: 5205



QUOTE (TritonAntares @ Feb 25 2010, 11:53 PM) *
May be one of the members is able to calculate the closest encounters until 2017 ?
Bye.


Try, use JPL HORIZONS Web-Interface to calculate distance Cassini - Iapetus smile.gif
http://ssd.jpl.nasa.gov/horizons.cgi


--------------------
Adam Hurcewicz from Poland
Go to the top of the page
 
+Quote Post
Floyd
post Feb 26 2010, 01:39 AM
Post #11


Member
***

Group: Members
Posts: 627
Joined: 4-September 06
From: Boston
Member No.: 1102



Hi Adam,
Tried your link, but I can't get it to leave earth for an observer point. What am I doing wrong?


--------------------
Floyd
Go to the top of the page
 
+Quote Post
Adam Hurcewicz
post Feb 26 2010, 01:47 AM
Post #12


Junior Member
**

Group: Members
Posts: 71
Joined: 29-January 10
From: Poland
Member No.: 5205



QUOTE (Floyd @ Feb 26 2010, 02:39 AM) *
Hi Adam,
Tried your link, but I can't get it to leave earth for an observer point. What am I doing wrong?


Try write:
@Iapetus
or
@608



--------------------
Adam Hurcewicz from Poland
Go to the top of the page
 
+Quote Post
Elias
post Feb 26 2010, 05:40 PM
Post #13


Junior Member
**

Group: Members
Posts: 30
Joined: 30-May 05
Member No.: 396



I am not sure if MIMI data can confirm the disk/rings scenario. What MIMI data may tell us is whether the structures that will be observed during the flyby in electrons and ions, under a much different geometry compared to the two previous flybys, are consistent with that exciting scenario (or not). Consistent observations under much different geometries, may strengthen the initial interpretation, but definitely not prove it.

I think proof can only come from imaging observations (or maybe other, more direct methods than those based primarily on charged particle data).
Go to the top of the page
 
+Quote Post
DrShank
post Feb 26 2010, 06:45 PM
Post #14


Member
***

Group: Members
Posts: 161
Joined: 6-March 07
From: texas
Member No.: 1828



QUOTE (Elias @ Feb 26 2010, 11:40 AM) *
I am not sure if MIMI data can confirm the disk/rings scenario. What MIMI data may tell us is whether the structures that will be observed during the flyby in electrons and ions, under a much different geometry compared to the two previous flybys, are consistent with that exciting scenario (or not). Consistent observations under much different geometries, may strengthen the initial interpretation, but definitely not prove it.

I think proof can only come from imaging observations (or maybe other, more direct methods than those based primarily on charged particle data).



if it cant be seen from orbit, the best case for corraborative proof then comes from the equatorial features i and others have shown above and elsewhere that are very difficult to attribute to anything but debris orbiting Rhea in a very thin and low density disk. but the motivation for the flyby is these "rings" so here's hoping they find something


--------------------
Go to the top of the page
 
+Quote Post
Elias
post Feb 26 2010, 09:20 PM
Post #15


Junior Member
**

Group: Members
Posts: 30
Joined: 30-May 05
Member No.: 396



QUOTE (DrShank @ Feb 26 2010, 07:45 PM) *
if it cant be seen from orbit, the best case for corraborative proof then comes from the equatorial features i and others have shown above and elsewhere that are very difficult to attribute to anything but debris orbiting Rhea in a very thin and low density disk. but the motivation for the flyby is these "rings" so here's hoping they find something



But the equatorial features may simply indicate that there was a ring sometime in the past, and its collapse has formed them. Is that right? Its not necessary that the ring system/disk still exists (although in the context of the MIMI observations, one may assume that).
Go to the top of the page
 
+Quote Post

6 Pages V   1 2 3 > » 
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 31st October 2014 - 11:07 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.