Friday, May 06, 2005

Still waiting on Tethys images?

I noticed a spike in website traffic today. I'm sure much of it has to do with the DISR and ISS images released yesterday but since site traffic spikes like today seem to be correlated with distance to Saturn and/or Titan, I am also guessing some of you are here for Tethys images. Well, they haven't shown up yet, not even at the JPL Raw images page. Rest assured once they show up there I will post them here.

UPDATE 05/05/2005 10:30am: I'm starting to get pessimistic about these images showing up, unfortunately. But hey, at least there are plenty of ring images to look at.

Update 05/06/05 11:49 am: Unfortunately these images appear to be lost. The images in the previous observation of the outer A ring were not as compressed as expected, causing ISS to go over their limit in data allocation for that particular playback period. This cut off the end of the outer A ring observations and the ISS Tethys observations (but not the VIMS Tethys observation that ISS was riding along with). I hope this explains what happened. As you can imagine, I am very disappointed in this. The computer I work on here at the lab is named "Tethys" and I was hoping to have a nice mosaic of said moon for a background image...

3 Comments:

Anonymous Anonymous said...

Greetings Jason,

Do you happen to know if the Tethys images were in fact returned to Earth? Is this simply a bug on the JPL raw images page or is something else going on?

Thanks,

Steve Albers

5/05/2005 05:00:00 PM  
Anonymous Phil Stooke said...

Far be it from me to comment on something I know very little about... oh, wait, that's what the internet is for! - OK, the Tethys image situation is very unfortunate. But it does suggest some data management issues, and I hope they are being thought about. In the 'old days' we had uncompressed images and data on tape, and the spacecraft just ran through the tape and played it all back, and people knew how big each file was going to be. This is completely different... compression is a bit unpredictable and the storage is random access.

So how can the Tethys image cutoff situation be avoided in future? Maybe by sending half the ring images, then half the Tethys images, half of any other target images... and then going back to get the other half with the risk of a premature cut-off? Or ensuring certain files are not overwritten until it's certain we have them on the ground? I know the mission is complicated enough without having to add more to it, but maybe the half and half approach is not a big deal to implement? Judging by the paucity of images in a few other situations I have a hunch this has happened before...???

Phil

5/08/2005 06:57:00 AM  
Blogger Jason said...

It can also be corrected by incorporating these latest results on the compression of ring images into future observations.

5/09/2005 12:07:00 PM  

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