IPB

Welcome Guest ( Log In | Register )

2 Pages V   1 2 >  
Reply to this topicStart new topic
Rev 165 Apr 23-May 11 2012, Enceladus E19 and close Dione flyby
jasedm
post Apr 22 2012, 08:25 PM
Post #1


Member
***

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



The latest looking ahead article is available.

This revolution includes another 74km Enceladus flyby with infrared studies on approach and recession, and RSS as prime instrument at C/A for gravity readings over the south pole. We don't get this close to Enceladus again now until October 2015.

Also a close Dione flyby at around 8000km with some great hi-res imaging and mosaics to look forward to, and some distant Titan cloud hunting.




Go to the top of the page
 
+Quote Post
jasedm
post May 2 2012, 05:29 PM
Post #2


Member
***

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



Initial far-encounter images have landed - Enceladus from distance, and some nice plume shots.

Can anyone explain this image? The top half is fairly 'clean' but the bottom half is speckled with cosmic-ray hits and sundry noise - I've not seen this before, how does it occur in the same image??

Looking forward to what should be some splendid close Dione pics....
Go to the top of the page
 
+Quote Post
ugordan
post May 2 2012, 06:54 PM
Post #3


Senior Member
****

Group: Members
Posts: 3570
Joined: 1-October 05
From: Croatia
Member No.: 523



QUOTE (jasedm @ May 2 2012, 07:29 PM) *
Can anyone explain this image? The top half is fairly 'clean' but the bottom half is speckled with cosmic-ray hits and sundry noise - I've not seen this before, how does it occur in the same image??

I forget the exact technical reason, but in essence the CCD readout speed overwhelmed the speed the downstream components can handle (say if the spacecraft recorder configured telemetry rate was set lower) so the lower part of the image was forced to sit on the CCD for a while longer. This increases dark current background (brightening seen visible) as well as chances of cosmic ray hits. BTW, this complicates dark current calculations for calibration quite a lot.

Chances of this happening depend on whether both cameras are active simultaneously, binning and compression mode, spacecraft telemetry pickup rates (the speed at which ISS sends packets to the spacecraft recorders, which also depends on whether other instruments are actively collecting as well).


--------------------
Go to the top of the page
 
+Quote Post
brellis
post May 2 2012, 07:37 PM
Post #4


Member
***

Group: Members
Posts: 710
Joined: 9-February 07
Member No.: 1700



ugordan, you understand that from an armchair? In Croatia? Why haven't they hired you yet? smile.gif
Go to the top of the page
 
+Quote Post
ugordan
post May 2 2012, 07:41 PM
Post #5


Senior Member
****

Group: Members
Posts: 3570
Joined: 1-October 05
From: Croatia
Member No.: 523



It's explained in the extensive Porco, et. al. paper from 2004 about Cassini's ISS. Since I had to reverse-engineer most of the official calibration code for my purposes, I kind of needed to know things like this about the cameras...


--------------------
Go to the top of the page
 
+Quote Post
jasedm
post May 2 2012, 07:50 PM
Post #6


Member
***

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



Wow! comprehensive answer ugordan, makes a lot of sense - thanks!

Jase
Go to the top of the page
 
+Quote Post
stevesliva
post May 2 2012, 10:32 PM
Post #7


Senior Member
****

Group: Members
Posts: 1169
Joined: 14-October 05
From: Seattle
Member No.: 530



Sounds like an interesting tradeoff between adding the additional complication of a dedicated buffer, or not. Since the buffer would be just another thing that could break.
Go to the top of the page
 
+Quote Post
ugordan
post May 3 2012, 07:48 AM
Post #8


Senior Member
****

Group: Members
Posts: 3570
Joined: 1-October 05
From: Croatia
Member No.: 523



There is a buffer, it's just not large enough to hold an entire unbinned frame. More on this in section 3.9.4. of the ISS paper I mentioned.

Now back to your regular science program schedule...


--------------------
Go to the top of the page
 
+Quote Post
Phil Stooke
post May 4 2012, 03:54 AM
Post #9


Senior Member
****

Group: Members
Posts: 5760
Joined: 5-April 05
From: Canada
Member No.: 227



http://saturn.jpl.nasa.gov/photos/raw/?start=1

Beautiful new pictures of Enceladus and Dione. I love the set with the big impact basin right at the top of the disk of Dione and Saturn behind it.

Phil



--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
elakdawalla
post May 5 2012, 12:08 AM
Post #10


Bloggette par Excellence
****

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



I put together just a few of the goodies from this flyby: http://www.planetary.org/blogs/emily-lakda...2/05041544.html

But I can't believe I'm the first one to post any of these, with the first images having been on the ground for more than 24 hours now. Hellooooo! This is a forum about image processing! There are so many more awesome pictures from this flyby to play with! Is anybody else out there interested in playing and sharing?


--------------------
My blog - @elakdawalla on Twitter - Please support unmannedspaceflight.com by donating here.
Go to the top of the page
 
+Quote Post
Ian R
post May 12 2012, 12:05 PM
Post #11


Member
***

Group: Members
Posts: 553
Joined: 18-July 05
From: Plymouth, UK
Member No.: 437



This one's for Phil and Emily ...

Attached Image


--------------------
Go to the top of the page
 
+Quote Post
Phil Stooke
post May 12 2012, 06:04 PM
Post #12


Senior Member
****

Group: Members
Posts: 5760
Joined: 5-April 05
From: Canada
Member No.: 227



Thanks! Very nice.

Phil



--------------------
... because the Solar System ain't gonna map itself.
Go to the top of the page
 
+Quote Post
Ian R
post May 24 2012, 10:53 PM
Post #13


Member
***

Group: Members
Posts: 553
Joined: 18-July 05
From: Plymouth, UK
Member No.: 437



This is an enhanced IR-GREEN-UV view of a crater at 132 degrees W, 53 degrees N, which lies between the two principle arms of Arpi Fossae:

Attached Image


--------------------
Go to the top of the page
 
+Quote Post
brellis
post May 24 2012, 11:25 PM
Post #14


Member
***

Group: Members
Posts: 710
Joined: 9-February 07
Member No.: 1700



Ian, I feel like I'm looking at a seashell - wow! thanks
Go to the top of the page
 
+Quote Post
Ian R
post May 27 2012, 06:18 AM
Post #15


Member
***

Group: Members
Posts: 553
Joined: 18-July 05
From: Plymouth, UK
Member No.: 437



You're welcome! smile.gif I've added two more frames, turning it into a mosaic:

http://www.flickr.com/photos/10795027@N08/...57624830467026/


--------------------
Go to the top of the page
 
+Quote Post

2 Pages V   1 2 >
Reply to this topicStart new topic

 



RSS Lo-Fi Version Time is now: 31st October 2014 - 08:05 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.