Q & A With Steve Squyres, Coming in September Options

[djellison]

As previously reported, there's a great lineup of speakers at the BAA out of London meeting on September 3rd - including MER Principle Investigator Steve Squyres.

Steve has kindly offered some of his time so that we can meet up and do a Q'n'A based on questions submitted by you lot.

Obviously - there will be loads and loads of questions you want to ask and only so much time in which to ask them - however - I'll do what I can to pick as many of the best as I can squeeze in in the time available.

There will be a write up here, obviously, and I will try and record it as an MP3 and post that here as well.

Steve's book 'Roving Mars: Spirit, Opportunity and the Exploration of the Red Planet' is published next week - and a signed copy will be winging its way to the person submitting the best question! *

If you have questions you want me to pitch to Steve, then drop me an email to doug@rlproject.com with the subject SS Q&A

As a heads up - please take note of the other speakers at the BAA meeting - and if you have specific questions you'd like asked of them - I'll do my best to try and get them in after their presentations at the meeting. The last two ( Profs Greeley and Muller ) are on the Sunday and the Friday respectively, but I will be trying to get down to those presentations as well - but no promises.

-Prof. Carolyn Porco, Principal investigator, Cassini imaging system
-Prof. John Zarnecki, Principal investigator, Huygens surface science
-Prof. Mike A'Hearn, Principal Investigator, Deep Impact,
-Prof. Ron Greeley, Scientist on several planetary missions, Chairman of NASA & NAS Mars exploration panel
-Prof. Jan-Peter Muller, Scientist on Mars Express hi-resolution camera team, University College London.

Doug
* 'best' to be picked by SS and myself on the day

[elakdawalla]

The discussion about image resolution jogged my memory about the discussions I had with Jim Bell way back in October 2003 when the MER teams were doing their first real rehearsals. He was helping us figure out the best set of images we could get of the Red Rover Goes to Mars DVD within the smallest bandwidth footprint. Originally the planned sequence included L256R2, approximate color plus stereo. (The stereo was in there because the "Astrobot" at the center of the disk was once a lovely machined 3D LEGO astronaut, but due to requirements from NASA HQ the poor Astrobots were flattened into stickers.)

Anyway, when we got the test set of images back the Astrobot had disappeared from both the L2 and R2 images -- turns out the flight-qualified label material we used was transparent at 750 nanometers! Fortunately, Jim was able to get some different filter choices substituted into the final sequence. One of his suggestions is appropriate to this discussion: "I would like to replace R2 with L1 (empty), which gives the highest resolution image detail in Pancam images. We will use a lower amount of compression for this filter to maximize image detail. The compression level will be set so that the total data volume for the new version of this sequence does not exceed the data volume of the existing version."

In other words, as helvick pointed out, it's likely that in each image sequence from the rovers, one or two -- most commonly L2 and R2, and occasionally the L456 if they are planning on making a particularly lovely press product -- are sent with lower compression. The rest, which are taken only for color information, are sent with higher compression rates -- not necessarily subsampled (though that would be another way to do it), just compressed more. When they were writing the sequences in ops during the mission they usually talked about compression rates of 8:1 vs 20:1, stuff like that, though I'm not sure if I'm remembering the exact choices of ratios correctly. This is particularly true for full 14-filter sequences that go all the way out into the infrared. A full multispectral stack of images contains in it a LOT of redundant information -- areas in light and shadow are lighter and shadowed in every image in the stack. They reduce the redundancy by compressing many of the images that are there just for spectral info at a higher rate. (Writing that down, I wonder why they don't consider ratioing the R3-7 bands with the R2 band before sending the data to Earth -- that would cut down on the redundancy. Hmm.)

--Emily