Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene, Also distant Iapetus |
Rev 127 - Feb 22-Mar 12, 2010 - Rhea R2 and Helene, Also distant Iapetus |
Feb 20 2010, 04:29 AM
Post
#1
|
|
Administrator Group: Admin Posts: 5172 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 website - My Patreon - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
|
|
|
Feb 20 2010, 04:33 AM
Post
#2
|
||
Senior Member Group: Moderator Posts: 3231 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): 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 |
|
|
||
Feb 21 2010, 08:28 AM
Post
#3
|
|
Member Group: Members Posts: 655 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. |
|
|
Feb 21 2010, 11:23 AM
Post
#4
|
|
Member Group: Members Posts: 288 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. |
|
|
Feb 21 2010, 02:15 PM
Post
#5
|
|
Member Group: Members Posts: 910 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.
-------------------- |
|
|
Feb 23 2010, 01:06 AM
Post
#6
|
|
Member Group: Members Posts: 813 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 |
|
|
Feb 23 2010, 03:38 AM
Post
#7
|
|
Member Group: Members Posts: 903 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 . . . . |
|
|
Feb 25 2010, 06:31 PM
Post
#8
|
|
Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, 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 -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
|
|
Feb 25 2010, 10:53 PM
Post
#9
|
||
Member Group: Members Posts: 288 Joined: 28-September 05 From: Orion arm Member No.: 516 |
So,
about 75 images are online. Here a quickout: 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. |
|
|
||
Feb 26 2010, 12:54 AM
Post
#10
|
|
Member Group: Members Posts: 102 Joined: 29-January 10 From: Poland Member No.: 5205 |
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 http://ssd.jpl.nasa.gov/horizons.cgi -------------------- Adam Hurcewicz from Poland
|
|
|
Feb 26 2010, 01:39 AM
Post
#11
|
|
Member Group: Members Posts: 910 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? -------------------- |
|
|
Feb 26 2010, 01:47 AM
Post
#12
|
|
Member Group: Members Posts: 102 Joined: 29-January 10 From: Poland Member No.: 5205 |
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
|
|
|
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). |
|
|
Feb 26 2010, 06:45 PM
Post
#14
|
|
Member Group: Members Posts: 207 Joined: 6-March 07 From: houston, texas Member No.: 1828 |
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 -------------------- Dr. Paul Schenk, Lunar and Planetary Institute, Houston TX
http://stereomoons.blogspot.com; http://www.youtube.com/galsat400; http://www.lpi.usra.edu/science/schenk/ |
|
|
Feb 26 2010, 09:20 PM
Post
#15
|
|
Junior Member Group: Members Posts: 30 Joined: 30-May 05 Member No.: 396 |
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). |
|
|
Lo-Fi Version | Time is now: 19th April 2024 - 03:09 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. |