Galileo WebChat - July 18, 1996
6PM - 7PM PDT

Spacenut: . . . . Thu, Jul 18, 5:56PM PDT (-0700 GMT)
Thank you Duane! Another question: Didn't the one-week early arrival at Ganymede change the rendezvous configurations with moons on future orbits? How was this compensated for?

Duane Bindschadler Magnetometer/Dust Detector Team, JPL: . . . . Thu, Jul 18, 6:00PM PDT (-0700 GMT)
Spacenut: Hmm. If one of the NAV guys is on, they'd answer this better than I can. But let me try. Essentially, we got to Ganymede exactly one Ganymede orbital period early. So Ganymede was in exactly (or almost) the same position as originally planned. Apparently, one can then find orbits which put Galileo back at Ganymede right on the original schedule for the 2nd Ganymede encounter. After that, Galileo was "back in the pipeline" for the rest of it's planned tour. It's cool, but i wish i understood how they did it!

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 6:11PM PDT (-0700 GMT)
Basically the velocity change can be controlled by varying the geometry of the flyby. The Io flyby was a bit low, so the spacecraft was decelerated more than planned. This resulted in the initial orbit being shorter than planned, and thus the orbiter arrived back in the vicinity of Jupiter a week earlier. As stated, Ganymede happened to be in about the same place. The way I understand it, the G1 flyby was designed to modify the orbit to pull in the apojove (far point) and set up for the second Ganymede encounter. THAT flyby will be designed to throw the spacecraft a bit further than originally planned, resulting in it arriving a week later, or back in the originally planned "groove." Lou D'Amario explains this stuff very well...

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:01PM PDT (-0700 GMT)
Seattle: All of the images will be made public (except those that didn't work). There will be a 1-2 week latency before images are released (usually on the GLL Web page)

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:00PM PDT (-0700 GMT)
Seattle, there is a lag time of the release of images.

Bill Arnett: Yes, there's certainly a lot of new features on Ganymede that we didn't see in Voyager! For instance all of those ridges in Uruk Sulcus showed up as only a few linear bands on light and dark pixels in Voyager. Very tantalizing, but not enough info to make geological interpretations from the Voyager images. Now with the new Galileo images, us geologists (especially the sort concerned with faults) are having a field day!

Eileen Ryan, Imaging Team, NOAO/PSI: . . . . Thu, Jul 18, 6:06PM PDT (-0700 GMT)
For Bill Arnett: Hi Bill! I'm really grateful for the "Nine Planets" resource webpage--just wanted to put in an acknowledgement. As for new features on Ganymede: with the increased resolution, I was really struck by the crater morphology. We don't know alot about cratering on icy surfaces, yet the craters on Ganymede seem very different from what I expected (based on past images and laboratory ice-impact data). That'll have me thinking for awhile...

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:04PM PDT (-0700 GMT)
An additional set of data containing ultraviolet spectral information on Jupiter's aurora, atmosphere, Ganymede's (potential) atmosphere, and the Io torus will also be analyzed over the next few weeks.

Stephen Licata GLL Mission Control Team: . . . . Thu, Jul 18, 6:07PM PDT (-0700 GMT)
abrown: I think that when Cassini makes its flyby of Jupiter, it will kind of on the "fringes" of the Jupiter system (6 million miles from Jupiter???). That's enough to take a few good pictures of Jupiter from farther back (i.e. more chance of a "global shot" - not possible with galileo because we're now too close). This all depends on NASA because, at present, I think that the Cassini mission isn't funded to do any "warm-up encounters". I sure hope they get to do it. BTW, when Jupiter swings past Earth on its way to Jupiter, it will be going very fast. I think it will either tie or break the Ulysses spacecraft's record of "fastest track to Jupiter" ~ 13 months! Unfortunately, the trip from Jupiter to Saturn will take another 3 years!

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:07PM PDT (-0700 GMT)
abrown: . . . . Thu, Jul 18, 6:14PM PDT (-0700 GMT)
Is the 6 million mile distance Cassini would have dictated by orbital mechanics, or could they get in closer? Why wouldn't they fund gathering data from Jupiter, since it would be significatly less expensive than sending another probe?

Wisdom: . . . . Thu, Jul 18, 6:03PM PDT (-0700 GMT)
Since it Saturn is farther from the sun will Cassini's pictures need to be exposed for significantly longer than Galileo's?

Stephen Licata GLL Mission Control Team: . . . . Thu, Jul 18, 6:27PM PDT (-0700 GMT)
abrown: You may want to check out the Cassini home page here at JPL (try starting at button as a guess). There probably are alot of reasons for the 6(?) million mile flyby distance - orbital mechanics, avoid the radiation, etc. I'm not really qualified to answer that one. BTW, in case you were wondering, the Galileo telemetry system is quite different from that of Cassini so Cassini can't be a relay satellite for Galileo, even if Galileo still had funding to be "alive" when Cassini passes by in 2001. :-(

Duane Bindschadler Magnetometer/Dust Detector Team, JPL: . . . . Thu, Jul 18, 6:06PM PDT (-0700 GMT)
Mark DunK: I haven't heard any updates of the *highly* speculative ideas that you've described. Unfortunately, dropping a single probe into the atmosphere of the largest planet in the solar system is not a really optimal way to look for life there.

Greg McKay: . . . . Thu, Jul 18, 6:09PM PDT (-0700 GMT)
Mark Dunk: I seem to remember reading something about floaters and sinkers a few years ago. I never read sci-fi, only Astronomy magazine. It had to be a story in Astronomy Magazine

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 6:02PM PDT (-0700 GMT)
Geoff, laborde@jpl.nasa.gov should work.

John Krikawa (JK) jkrikawa@ccit.arizona.edu: . . . . Thu, Jul 18, 6:04PM PDT (-0700 GMT)
Geoff: address above, thank you.

Ted Stryk: . . . . Thu, Jul 18, 6:01PM PDT (-0700 GMT)
Why couldn't the remaining images that can't be transmitted be sent back as some kind of a high loss jpeg or somthing. Also, what are the images that can't be returned of? (Jupiter or the Moons?)

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:06PM PDT (-0700 GMT)
Ted Stryk: We don't have JPEG on the spacecraft. Remember that the computer on GLL is 20+ years old. We only have about 160Kbits (yes Kbits, not Mbits) of memory onboard for processing data. The "deselected" images are: 1 of Ganymdede and 11 of Europa. On the bright side, we are getting much better data compression for G1 than we expected. So we may actually have the downlink to return some of these images.

Kevin. Baines, Jupiter NIMS Co-I: . . . . Thu, Jul 18, 6:02PM PDT (-0700 GMT)
One of the most provocative questions we're trying to answer is "Why is the Red Spot red". I find it best to think about this feature as blue-absorbing, rather than "red", ie.e, the best guess is that there's an absorber imbedded as part of the haze/cloud structure that absorbs uv and blue light. We are not sure what the substance is. Given the wide spectral power afforded by the SSI Uv-visible-near-ir filters and the NIMS filters, which together cover something like 0.3 to 5.2 microns, and the high spatial resolution Galileo affords (allowing us to isolate the reddest wisps), we really hope to get a clean spectrum of the material to try to figure out what it is....

Science Teacher LP: . . . . Thu, Jul 18, 6:06PM PDT (-0700 GMT)
Perhaps I should direct my question to a member of the team who deals with light. I'll rpeat it. When fifteen year ols students ask a question such as "Why is the Eed Spot red?" what shoul I tell them? Does it have something to do with the compositionof the gases or how the particles move? Wondering how to give an answer which does not overlook the real science in this...

Science Teacher LP: . . . . Thu, Jul 18, 6:09PM PDT (-0700 GMT)
Thanks to Kevin Baines....and if I might get more details on this....so you believe there might be some particles in the atmosphere which absorb all but the red parts of the spectra? So the model we now use to explain reflection will be accurate?

Duane Bindschadler Magnetometer/Dust Detector Team, JPL: . . . . Thu, Jul 18, 6:10PM PDT (-0700 GMT)
science teacher LP: Kevin Baines tried to anwer your question. Although maybe not an anwer you'd want to try to give 15 year-olds! The short of it is that the gases in the Red Spot absorb bluish wavelengths preferentially. So red-colored light is reflected more strongly. But I don't think anyone knows yet *what* gases are responsible

Science Teacher LP: . . . . Thu, Jul 18, 6:14PM PDT (-0700 GMT)
Thank you Duane B and W, K, Toniska- fifteen year olds will definitley understand that. The curriculum here does a good job of explaining basic principles of light and we spend a lot of lab time on this topic. The stidents LOVE this topic and this fall I will have a student interne to help with the labs........SciencePlus curriculum has done SO much to improve the understanding of the physical sciences to students. And now that our school is connected to the 'net more and more science becomes accessible, thanks to people like you!

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:19PM PDT (-0700 GMT)
Science Teacher LP - you're welcome. You might want to visit the web site here over the next several weeks. We will be releasing one image per day of the Great Red Spot (6 images will give the full mosaic in one color).

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:24PM PDT (-0700 GMT)
Science Teacher LP - there has been a campaign on the part of the SSI (camera), the Near Infrared Imaging Spectrometer (NIMS), the Ultraviolet Spectrometer (UVS), and the Photopolarimeter Radiometer (PPR) to produce the first combined look at the Red Spot in this first orbit. NIMS and PPR data are still on the recorder and will comes to the ground in the next few weeks. SSI (image) and UVS data are on the ground and are being processed as we speak!

John Krikawa (JK) jkrikawa@ccit.arizona.edu: . . . . Thu, Jul 18, 6:25PM PDT (-0700 GMT)
The clarity of the first GRS image is stunning. I am so pleased to know that 5 more are coming. I need to go soon, but wanted to say how cool it was going out in the eve. of the G1 encounter and looking at Jupe and it's tiny specs of orbiting lights, thinking we sent this little floating box out there in the great vacuum, and now it's taking pictures for us. How exciting! Thank you.

Science Teacher LP: . . . . Thu, Jul 18, 6:25PM PDT (-0700 GMT)
Thank you W, Kent Tobiska and Geoff Collins. The clarity of your answers will make it easier to explain what is happening 'out there'. At school we have to deal with conceptual levels and personal experiences differently but i hate to slide past the issues of good science or to water down answers for students. Too many things in the curriculum become distorted this way. This is such a good service to teachers and I thank you for it.

Philippe Poiré - a member of the Probe team could answer that question better but apparently one channel of telemetry was lost followed by a second channel (and the last) several minutes later.

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 6:17PM PDT (-0700 GMT)
The Probe data did not just stop *BAM!*. Enough data regarding the performance of the Probe's systems was returned at the last to give a pretty clear picture of what happened. The signal(s) finally died when some component could not take the heat. TWIUI (The Way I Understand It - I say that a lot) the Probe's transmitters were actually designed NOT to reject the heat they produced. Apparently they got hotter and hotter as they operated, until they were finally too hot. This was intentional, to prevent contamination of the measurements of Jupiter's environment. They were also designed so that they would not reach fatal temperatures until after the mission was concluded, which is what happened to first order. You'd have to ask a Probe guy to be sure, however. I am just a Systems guy.

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:05PM PDT (-0700 GMT)
W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:11PM PDT (-0700 GMT)
Hello Cal Grant! Thanks for your support. We made it to Jupiter and the data so far is phenomenal! Science Teacher LP - the Red Spot is red due to the composition of the gases that are found in it. Kevin Baines (who just left) could answer which gases cause the red color. But the bottom line is that the color comes from the composition of gases.

Cal Grant: . . . . Thu, Jul 18, 6:15PM PDT (-0700 GMT)
Kent! I know! I've been following it all on the web page - Thanks to everyone who maintains it! I would ask some questions but everyone else's are informative enough! Besides... :-)

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:09PM PDT (-0700 GMT)
Andrew, the lineaments on Europa cover the entire body (as far as we can tell from Voyager). The Voyager images have a large jump in resolution from so-so to real bad and perhaps what you saw was a drop in resolution (which makes it more difficult to see the "cracks")

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:13PM PDT (-0700 GMT)
Andrew: About the cracks on Europa, they _do_ have an organized pattern having to do with the orientation towards Jupiter, and I'm very excited that they may have been caused by movement of Europa's tidal bulge.

Andrew: . . . . Thu, Jul 18, 6:17PM PDT (-0700 GMT)
Geoff Collins: Indeed. Almost like an egg shell cracked down the middle from the push and pull.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:14PM PDT (-0700 GMT)
Seattle, the lag in image release is about 1 to 2 weeks. The images come down in 'packets' of eight lines each, which then have to be reassembled on the ground into a whole picture. They need to be 'cleaned up' if lines were missed or for other reasons. We are very much aware of the public's desire to see the images (we're dying to see them ourselves). We are doing our best to get them out.

Seattle: . . . . Thu, Jul 18, 6:20PM PDT (-0700 GMT)
Kelly, thanks for your clarification of the lag-time in getting the images out to the public. The Imaging Team's efforts are very much appreciated. Keep up the good work!

Elizabeth Alvarez, Imaging Team, NOAO: . . . . Thu, Jul 18, 6:24PM PDT (-0700 GMT)
The Galileo project is very eager to share with the public the excitement of new discoveries being made. Once an image is received on the ground it undergoes some basic processing. As soon as we're able to put together a complete image and include some explanatory text, we try to release the images on our public and educational outreach pages. We try to offer background info. so as to help people understand how to interpret the data and the context of a particular image in terms of the mission science goals.

Kataan: . . . . Thu, Jul 18, 6:12PM PDT (-0700 GMT)
Hello all. I am curiuos as to whether Europa or any other of Jupiter's sattelites can support life, and if there is going to be any tests to satisfy these questions.

Mark Dunk: . . . . Thu, Jul 18, 6:14PM PDT (-0700 GMT)
RE: Life on Jupiter. The article simply speculated on how life-forms would need to be put together in order to survive (basially, bouyant life forms feeding on each other, maybe some life form at the top of the food chain, and many smaller, "bottom-feeders" utilizing atmospheric gases as "Plankton.") Strictly speculative, but I find intellectual activities like this to be stimulating for high school science students.

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:16PM PDT (-0700 GMT)
Kataan - As far as we know at this time, none of the Galilean satellites can support life as we know it. However, the wonder of the discoveries of science we are engaged in is that we find surprises every day! As far as I know, for example, the possibility of a liquid water ocean underneath a Europa ice crust has not been ruled out.

Kataan: . . . . Thu, Jul 18, 6:18PM PDT (-0700 GMT)
So, in regards to Europa, can the instruments on Galileo detect the composition and temperature under the ice crust, or is that specific area limited to monitoring?

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:19PM PDT (-0700 GMT)
Science Teacher LP, Kataan: We're a _long_ way from having any real evidence for or against life. The existence of organic molecules is speculated, because the right elements are floating around, and organic compunds have been found on comets, I think, but what we really need are samples from Europa, and we're a long way from having the money and technology to do that. _IF_ Europa has a liquid water ocean, which we will know better about after the Galileo mission, it is within the realm of possibility for there to be life.

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:28PM PDT (-0700 GMT)
Kataan: About measuring what's happening below Europa's ice: we can only measure what's going on on the surface of the planet remotely. We would have to send a probe to the surface and below to get info on subsurface activity. But we can use remote measurements to construct models of what we think might be happening underneath. For instance, if we observe the cracks and the motion of Europa's ice shell, we can try to use that to determine if there's liquid below it, and how warm it might be.

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:14PM PDT (-0700 GMT)
Ted Stryk: There is limited scientific value to the OPNAV images. The resolution will not be good enough to see any plumes on Io. For that matter, I don't think there are any more OPNAVs planned for Io. They are mainly valuable for measuring gross refelctance properties, and for adjusting our planning models for setting camera exposures.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:18PM PDT (-0700 GMT)
Ted - opnav images are compressed so as to return only the bright limb and terminator (just enough for the nav team to confirm targeting). ALL images, including opnavs, are analyized. But with the compression, we would be lucky to see much. The opnavs of Ganymede showed albedo variations but not much else and nothing we didn't see later. I'm not sure we ever do opnavs of Io.

Duane Bindschadler Magnetometer/Dust Detector Team, JPL: . . . . Thu, Jul 18, 6:18PM PDT (-0700 GMT)
Ted Stryk: I don't think OPNAVs will be of much use. Unless i'm mistaken, they are all taken of the body that Galileo will have it's closest encounter with on each orbit - and there are no close encounters with Io planned (yet). In addition, the OPNAVs are heavily edited to show only a crescent part of a moon and a few stars. The data just off the lit part of the planet doesn't get returned -- and that's where we'd see plumes.

John Krikawa (JK) jkrikawa@ccit.arizona.edu: . . . . Thu, Jul 18, 6:16PM PDT (-0700 GMT)
I think a lot of us are excited about the Europa pictures/flyby's since Voyager left us with such tantalizing images. It is a beautiful moon. How much increase in resolution will the images be? Approximately 10x over the Voyager shots? I know the coverage will be more complete.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:19PM PDT (-0700 GMT)
Andrew, the Europa images are still on the spacecraft.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:24PM PDT (-0700 GMT)
Science Teacher LP - here at ASU we have actually brought in talented students (identified by their teachers) and had them participate in science projects with us (one high school sophomore worked on color analysis of Gaspra - real time). It works well for both parties - they see what the "world of science" is like - and we get great feedback for our efforts.

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:25PM PDT (-0700 GMT)
Sci. teacher LP: The mentoring idea sounds like a great one! I'm a grad student on a NASA educational fellowship currently working on some of the Galileo curriculum modules on the SEPO page, which are mostly aimed at a middle school level, adaptable up or down.

Mark Dunk: . . . . Thu, Jul 18, 6:23PM PDT (-0700 GMT)
I have to sign-off soon, but I would like to show support for Science Teacher LP's comments about mentoring. I would like to set something up, too. Email is markdunk@flash.net I am interested in cyber-pen-pals for my students, too.

Science Teacher LP: . . . . Thu, Jul 18, 6:31PM PDT (-0700 GMT)
Thank you Mark Dunk and Kelly Bender and the others who have reacted to the mentoring idea. It just seems as though we have a golden opportunity to connect with the talent in our youth and to give them a vision of all they may be....you are such wonderful examples of what can happen when outreach occurs...a heling hand and a 'reach for the stars'. You are an inspiration to those of us who labour 'in the trenches'. Yes we suffer dreadfully from curbacks, but we have good people who refuse to let it keep the kids from learning. We won a hard-fought govcernment grant at our school and have mangaed to keep our science lab. Now don't laugh- we run it for $800 a year; that's $2 per student...*Hey I said not to laugh!!!*

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:33PM PDT (-0700 GMT)
Sci. Teacher LP: I first got interested in this stuff during Voyager's encounter with Neptune -- stayed up all night to watch the NASA coverage on PBS. Gifted high school teachers also make a huge difference - I credit some of mine with getting me to where I am now...(in grad school)

Science Teacher LP: . . . . Thu, Jul 18, 6:33PM PDT (-0700 GMT)
Cynthia- saw your post....thank you. Maybe this idea will fly.......

Science Teacher LP: . . . . Thu, Jul 18, 6:34PM PDT (-0700 GMT)
Hope you grad studentsrealise I'm keeping a list of your names ...heh heh

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:35PM PDT (-0700 GMT)
Science Teacher LP - $2 per student is pretty good! I would be happy to help in anyway also.

Science Teacher LP: . . . . Thu, Jul 18, 6:37PM PDT (-0700 GMT)
This has been a wonderful experience but I must leave. I thank you for your time, sense of humour and your willingness to reach out to us........I'll wait a few minutes and will then fade from sight....

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:37PM PDT (-0700 GMT)
Science Teacher LP - good night! and thank you for joining us!

Mark Dunk http://www.flash.net/~markdunk/: . . . . Thu, Jul 18, 6:38PM PDT (-0700 GMT)
Thanks for an enjoyable evening. Keep up the good work. There are probably more of us teachers out here using your stuff than you realize. Ciao for now!

Elizabeth Alvarez, Imaging Team, NOAO: . . . . Thu, Jul 18, 6:40PM PDT (-0700 GMT)
I'm told that a few teachers on this line have asked about education curricula and links to Galileo. There are a few basic sources. The main JPL Galileo page button has a box for education outreach and offers various ideas for activities as well as resources. Our imaging team education and public outreach page button includes education 'modules' which integrate Galileo images and related concepts into the kinds of curricula which are taught in middle school. We're working directly with a middle school, but are trying to include enough info. that a teacher can adapt to a more advanced level. We currently have 2 modules on our page. We will have more by the fall semester. The modules up there now are specifically so we can get FEEDBACK from teachers so that we offer you something you can USE! Check out the imaging page, go to the education section, ... the modules have email addresses for sending comments ....

Science Teacher LP: . . . . Thu, Jul 18, 6:40PM PDT (-0700 GMT)
W. Kent Tobiska.......I'm counting on it!!!!!!!! There's are a lot of folks out there sending care and light....do you collect it and send it to us through the net? By the way i registered our school with the NASA proposal outreach on the net, and perhaps the mentoring idea will be considered. The school is A. J. Smeltzer Junior High School in Lower Sackville Nova Scotia...and we are on schoolnet in Canada. Thanks!!!!!!!!!!!!!

Elizabeth Alvarez, Imaging Team, NOAO: . . . . Thu, Jul 18, 6:43PM PDT (-0700 GMT)
... on education modules ... sorry about a typo in the main Galileo page address (The imaging one was correct.) The main page is button

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:25PM PDT (-0700 GMT)
anonymous: (from Espana) You should check out the Galieleo homepage located at button for more information about the entire mission.

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:29PM PDT (-0700 GMT)
Jose Luis - the first image of Io is on the galileo homepage you came through to get here - you decide if there is an eruption. Some interesting hints here and there.... Science teacher LP - yes, it's important to motivate students if they have an interest. If your students have particular questions about the aurora and atmosphere of Jupiter, please have them send us questions to the addresses on the Galileo homepage.

Elizabeth Alvarez, Imaging Team, NOAO: . . . . Thu, Jul 18, 6:30PM PDT (-0700 GMT)
Hi, Kelly. Eileen made me send my msg. before I could write the full novel that I had begun. Geez, I was just revving up. Considering how sleep deprived I am right now, I better not stay on too long. I don't think I'm very coherent.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:31PM PDT (-0700 GMT)
Are there any non-galileo team members out there right now?

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:31PM PDT (-0700 GMT)
Liz: Who needs coherence? :)

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:34PM PDT (-0700 GMT)
Steve Collins Galileo Backroom (Attitude Control): Yes, there was much more contrast than was expected. The bright areas are bright becasue of a combination of 1) that part of the surface is more perpendicular to the incoming sunlight, and 2) the intrinsic brightness of that part of the surface is brighter. Geoff may want to expand upon this (or even correct some if it :-) )

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:35PM PDT (-0700 GMT)
Steve: from looking at some of the Gan. images in stereo (there's about 50-100 pixels of overlap between some hi-res images), I'd say that mostly the bright regions are high and the dark ones are low.

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:36PM PDT (-0700 GMT)
Cal... good night! Glad to have connected with you! I'll mention to the vanpool I *saw* you on the net!

Cal Grant: . . . . Thu, Jul 18, 6:38PM PDT (-0700 GMT)
Koool! Take care, keep up the great work! We're all watching! Especially us ex-JPLers! ;-)

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:34PM PDT (-0700 GMT)
Jim Kaufman - are you still there to field the Io image question?

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:36PM PDT (-0700 GMT)
Ted Stryk: Io is observed pretty much uniformly through out the tour. Give me a few minutes and I might be able to find some more numbers.

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:39PM PDT (-0700 GMT)
Ted Stryk: We have about 60 separate Io observation planned for the entire tour.

Gerald Hoehn from Germany (ghoehn@cats.ucsc.edu): . . . . Thu, Jul 18, 6:35PM PDT (-0700 GMT)
It seems to me that the four or so Galileo pictures from the Uruk Sulcus region on Ganymede are a not exactly at the position as showed in the planning pictures at button (maybe the target is missed by half a picture length) The pictures are also not overlapping. Was there a problem with the navigation or is it simply not possible to point the camera more exactly ?

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:39PM PDT (-0700 GMT)
Germany - the Ganymede frames don't overlap because the compressor ran out of bits before it hit the end of the line (the image had so much going on that there wasn't enough time to finish compressing every line)

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:37PM PDT (-0700 GMT)
Germany - the planning pictures on the sepo page were put together useing the original navigation. With the one week change in arrival, things were in a slightly different place. We didn't have time to update the planning image, and figured with the actual images almost upon us that there wasn't the need to fix them.

Sephen Licata GLL Mission Control Team: . . . . Thu, Jul 18, 6:43PM PDT (-0700 GMT)
Ted Stryk: (Speaking for Marcia Segura of the NIMS Team who is sitting here with me): Yes, Ted, Throughout the entire Galileo tour of Jupiter, numerous observations of Io are taken. We refer to those observations as Io monitoring. NIMS will look for "hot spots" in the thermal range of the instrument and for surface composition as well. This campaign includes both day and night side observing. We are anxiously waiting for 10 of those observations currently on the spacecraft tape recorder. We expect to see that data sometime mid-August.

W. Kent Tobiska, Galileo Ultraviolet Spectrometer Team, JPL: . . . . Thu, Jul 18, 6:39PM PDT (-0700 GMT)
Mark Dunk - good night... thanks for stopping by!

Stephen Licata GLL Mission Control Team: . . . . Thu, Jul 18, 7:05PM PDT (-0700 GMT)
abrown: Answer to Q1: Having the high-gain antenna would enable us to take MORE pictures, some in real-time but a lot would still be recorded around closest approach. For example, on orbits that carry us inside of 15 Jupiter radii (i.e. flybys of Io, Europa and Callisto), we would have to store the SSI (visible light) images on tape anyway because of the effect of the radiation environment on the Charged Couple Device imaging part of the camera. Also, around closest approach, things are happening very quickly. Evennow, with this latest encounter, there wasn't a minute when the science instruments just "sat around because there was nothing to record". Sure, a higher data rate would allow more images, but (and I'll have to defer to the imaging team folks out here) there is only so much time between satellite encounters to take and return data. The best pictures of a satellite really are within 24 hours of closest approach. Furthermore, during the "cruise" part of each orbit, the spacecraft has to take a lot of Optical Navigation images. During this time, both Jupiter and the approaching satellite are crescents as illuminated by the Sun (not too good for making maps! - even then on closest approach you only get to see 1/2 of the satellite anyway)So, it seems like the loss of a high-gain antenna stops us from taking time-lapsed movies of Jupiter on Approach from Earth (like Voyager). Now that we are in orbit, Jupiter is SO BIG, that a shot of the Red Spot that just came down took 6 SSI frames to capture it all. Overall, the Galileo Project estimates that it can fulfill about 70% of the original objectives. This includes 100% for the Probe. The idea is that "not all pictures are created equal". More downlink capacity would make everyone happy, but I'm not sure it would make a HUGE difference in the mapping of the satellites. Answer to Q2: Yes, the Galileo Project gets a lot of time on the Deep Space Network - the "biggest hog eats first at the trough"! However, we DO have to do a lot of negotiating with other projects and occasionally don't get the maximum viewing time possible over each station. For example, since Jupiter is in the southern sky at night, the best place to collect data from it is at the tracking station in Australia. They can "see" Galileo for almost 12 hrs per day. However, from the more northerly Madrid, Spain station, we can only get a few hours of good tracking each day because the spacecraft never gets too high above the horizon. We do the best we can and pretty much get everything we need, though we can be flexible (if necessary!) at certain times in the mission.

Jim Taylor - telecom: . . . . Thu, Jul 18, 7:24PM PDT (-0700 GMT)
Steve Licata gave a good answer to abrown's question a half hour ago about the amount of tracking time we get on the Deep Space Network. Yes, we get nearly 24 hours per day coverage from the largest (70-meter) antennas. Starting in November this year, we will get even more than that. How? We start "arrayed" operation. An array consists of several receiving antennas all working together, each with their own receiver. The Australian array could include the 70-meter antenna and two 34-meter antennas (all operated by the Deep Space Network) plus the "Parkes" 64-meter radio astronomy antenna. A full "intercontinental" array might include all those antennas plus the 70-meter Deep Space Network in California. Since the performance of an array is (roughly) proportional to the total area of all the antennas involved, an array can be more than twice as powerful as a single 70-meter antenna. That's why our maximum telemetry rate right now is 80 bits per second (bps), but could be the maximum of 160 bps next year during array operations.

Peter Hylen - Stockholm, Sweden: . . . . Thu, Jul 18, 7:09PM PDT (-0700 GMT)
Thanks Stephen, for your comprehensive answer..

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:46PM PDT (-0700 GMT)
Steve Collins: Well, there were a couple of versions of the flyover movie, one in which Eric DeJong "eyeballed it" or something like that (he wouldn't say how he made it), and a more recent one including some photoclinometry data. Photoclinometry is basically the technique of assuming that a surface has a constant albedo and some scattering function, so that hillslopes facing the sun are brighter than those facing away, and you then derive slope from how bright the pixels are. I think most of the brightness variation has to do with steep hillslopes, but there's some argument among imaging folks.

Steve Collins Galileo Backroom (Attitude Control): . . . . Thu, Jul 18, 6:51PM PDT (-0700 GMT)
Geoff: I've got no problem with taking a certain amount of artistic licence with presentation of the data to a non technical audience, I was just trying to see where the art stopped and the science began. I can't wait to hear some kind of interpretive music made from the fields and particles data. It would sound great behindthe flyover animation...

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:43PM PDT (-0700 GMT)
Seattle, see the answer I just gave Germany (compressor ran out of time)

Seattle: . . . . Thu, Jul 18, 6:46PM PDT (-0700 GMT)
Kelly, are you talking about compression performed as the images were being put on the tape recorder during the encounter, or during playback?

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:45PM PDT (-0700 GMT)
Peter Hylen - Stockholm, Sweden: How close is real close? We've got 70 m/pix pictures on the Web right now. We are currently playing back the 11 m/pix observation. I have seen about 1/3 of it. You should expect to see it on the Web in several weeks.

Peter Hylen - Stockholm, Sweden: . . . . Thu, Jul 18, 6:54PM PDT (-0700 GMT)
I meant the pictures taken from the closest distance of the passage- which I thought to be 835 kilometers... Anyway the pictures I saw from a dist. of 7000 kms were great! One is getting spoiled.. :-)

Kataan: . . . . Thu, Jul 18, 6:47PM PDT (-0700 GMT)
Personally, i think a visit to each of the moons would be a great expedition, and now with NASA finding more economic and less expensive methods to launch probes into space, i think that if it may be possible in the future, a visit to these moons surrounding Jupiter would provide incredible amounts of information. Additionally, because of Jupiter's size, it would almost be like an expedition into our own solar system.

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:46PM PDT (-0700 GMT)
Jewel Eye: Personally, I'd love to see a sample return mission from the Jupiter system...but I'd think that keeping a piece of ice frozen through the return trip would take some doing!

scorpion: . . . . Thu, Jul 18, 6:53PM PDT (-0700 GMT)
do you think it would be possible to send a manned mission to jupiter in spite of the intense difficulties it would encounter like the jovian radiation belts?

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 6:55PM PDT (-0700 GMT)
Jewel Eye: Well, there's not much that can replace a manned mission as far as finding out some crucial surface observations. Robots are OK for roving around the surface, but you would have to have a pretty intelligent one, since controlling it manually with the light-time delay would be impossible! Sending people presents the problems of long space flight, hard radiation around Jupiter, etc. If I had unlimited funds, I would send an orbiter in a polar orbit around each of the Galilean satellites (for high-res pictures and gravity measurements) and a network of probes to each surface for compositional and siesmic measurements and detailed pictures. Sending back a sample to Earth might be hard.

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:52PM PDT (-0700 GMT)
Kelly Bender, Galileo Imaging Team, ASU & Seattle: Yes, BARCing (pronounced "barking") is done in the camera hardware. BARCed images use less tape than ICT'ed images. And yes, the lines in the Ganymede images are permenantly lost. Sigh!

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 6:51PM PDT (-0700 GMT)
Brenda: I've been working on some educational activities related to Galileo... I'm sure others here can answer better than I, but as a first suggestion relating the images to things on earth (volcanoes, etc) is a way to make them more understandable / closer to home.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:52PM PDT (-0700 GMT)
Brenda, this is a real problem in science ed. (how much to simplify and how much to cover). A suggestion in using images, ask students what they see - they will answer based on their present level of knowledge - then have them investigate (do some research) what it might be. Left to their own devises, a student will teach themselves and may comprehend much more than what we would instincively reduce/simiplfy to.

Eileen Ryan, Imaging Team, NOAO/PSI: . . . . Thu, Jul 18, 6:54PM PDT (-0700 GMT)
Hi Brenda! Glad to see you'd like to use the images. Please check out the SEPO page button. Each time an image is released, we make an effort to put together a basic caption. If you still have questions about simplification, send email and I'm sure one of us responsible for SEPO update would be glad to help (and incorporate your suggestions).

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:52PM PDT (-0700 GMT)
Mathias: We've noticed changes in the optics, but not degradations.

Kelly Bender, Galileo Imaging Team, ASU: . . . . Thu, Jul 18, 6:55PM PDT (-0700 GMT)
abrown - we will be doing stereo imaging at Ganymede and Europa (but not at Callisto). The stereo images will be of limited areas.

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:56PM PDT (-0700 GMT)
Ted Stryk: HST data is being used especially for targeting the atmospheric observations on Jupiter. HST observations of Io do show changes in the surface. They add to our overall understanding of Io.

Andrew: . . . . Thu, Jul 18, 6:53PM PDT (-0700 GMT)
Are there any plans for another close Io fly-by at the end of mission (to make up for the lost imaging on the original fly-by)?

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 6:48PM PDT (-0700 GMT)
Ted Stryk: I think it will be much more likely that we will see the Jupiter Approach Image *before* the end of the mission. When we gain enough experience running our limping tape recorder, I think there is a good chance that we will be able to return that image. Incidentally, I have a vested interest in that image -- I took it!

Steve Collins Galileo Backroom (Attitude Control): . . . . Thu, Jul 18, 6:57PM PDT (-0700 GMT)
Jim Kaufman: I wouldn't hold your breath for the approach image. We did a burnout on the tape for what, most of a day... Some estimates I heard had us wear more than half way through the tape. Given what we know now, (and there's not a lot more info coming) it would be mighty dangerous to run that section of tape across the heads. If someone manages to talk O'Neil into it for the approach image, I want them on my next proposal team...

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 6:58PM PDT (-0700 GMT)
That's "burnISH," Steve-o, not "burnOUT". And it is not really "wearing through the tape," just the possibility of weakening it to 50% of its strength. I agree with your conclusion though.

Steve Collins Galileo Backroom (Attitude Control): Yes, but I thought that an air (or N2) bearing formed between the tape and the capstan almost immediately. That's why the tape didn't melt (or whatever) during the 18 hours before the DMS could be shut off.

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 7:03PM PDT (-0700 GMT)
I believe the "air bearing" theory was debunked quite some time ago. We're talking RUBBING here...

Steve Collins Galileo Backroom (Attitude Control): . . . . Thu, Jul 18, 7:04PM PDT (-0700 GMT)
Jim Kaufman: I think the air bearing theory died sometime after we began runing lab tests with the spare recorders.

Ted Stryk: . . . . Thu, Jul 18, 7:02PM PDT (-0700 GMT)
As to my question of the return of the approach image, if the spacecraft was out of propellant, what would there be to loose in sending it back?

Jim Kaufman, Galileo Imaging Team, JPL: . . . . Thu, Jul 18, 7:05PM PDT (-0700 GMT)
Ted Stryk: Yes, I would think that when the S/C runs out of propellant, we might finally be able to return the approach image.

Gregory LaBorde - Galileo Testbed and Systems Engineer: . . . . Thu, Jul 18, 7:05PM PDT (-0700 GMT)
That depends. If the spacecraft were out of propellant, there would be no attitude control. On the other hand, if it were oriented to point in a usable direction for downlink (like towards where the Earth is 80% of the time), it could still gather plenty of fields and particles data, for which the recorder might be useful. It would be a tradeoff. Of course, we would have to be in an attitude to allow downlink to get the image anyway, have sufficient power, etc. I agree, that if it looks like the spacecraft is failing, why not get the picture, but I think that will be a long time from now.

Geoff Collins, Brown University/Galileo Imaging Team: . . . . Thu, Jul 18, 7:02PM PDT (-0700 GMT)
John Krikawa: I'm not sure what you mean by "silvery"... It could be the high contrast. The Earth's moon does look gray and soft in a lot of places, but some other places are very rugged and contrasty, too. By the way, the Moon is very "silvery"...the full moon is something like three times brighter because of coherent backscattering - the same process that makes 3M reflective cloth or road signs so bright in your headlights.

Cynthia Phillips, Imaging team (LPL/ U. Arizona): . . . . Thu, Jul 18, 7:00PM PDT (-0700 GMT)
Jewel Eye: Some people have suggested that Pluto be called the "King of the Kuiper Belt" (the region of primitive objects lurking beyond Pluto in the outer solar system). But I think Pluto's been called a planet, so it's going to stay one, no matter how appropriate it is.