New Horizons at Io Options

[JRehling]

The map that Bjorn presents includes some Voyager data as well, so some of the changes seen between NH and this simulated view may actually be changes that occured between Galileo and Voyager.

"Io: Where the weather is also geology."

You can use that one.

[volcanopele]

I know. I just wanted to bring that up because I am sure someone will mention the change around Kanehekili, which was something we saw with Galileo.

[volcanopele]

Today, February 27, New Horizons conducts three, high-resolution mapping observations with LORRI and RALPH and an eclipse monitoring observation with LORRI, RALPH, and ALICE. The observations today focus on Io's anti-Jovian and trailing hemispheres.

Please keep in mind that these are simulations of the LORRI frames from Celestia, not the LORRI frames themselves...with one exception


The first observation, Ihires2, shows Io's anti-Jovian hemisphere Clat=9.1 S, Clon=203.0 W) from a distance of 2,691,322 km. The resolution with LORRI would be 13.3 km/pixel. The observation consists of both LORRI and RALPH frames (to look at Io in color and to examine the current distribution of hot spots). Pele has now rotated into view at lower left. The Prometheus plume should be visible at the terminator.


The second observation, Ihiresir2, shows Io's trailing hemisphere (Clat=8.9 S, Clon=238.2 W) from a distance of 2,645,200 km. The resolution with LORRI would be 13.1 km/pixel. Pele continues to be prominent in this observation, that includes compositional measurements from RALPH. How hot will Pele be in LEISA data? Will the Pele ring look different in MVIC data?


The third observation, Ihires3, will show Io's trailing hemisphere (Clat=8.4 S, Clon=267.2 W) from a distance of 2,679,220 km. The resolution with LORRI would be 13.3 km/pixel.



The final observation, Ieclipse3, shows Io's trailing hemisphere Clat=7.6 S, Clon=300.3 W) from a distance of 2,748,703 km. The resolution with LORRI would be 13.6 km/pixel.

[Bjorn Jonsson]

The map that Bjorn presents includes some Voyager data as well, so some of the changes seen between NH and this simulated view may actually be changes that occured between Galileo and Voyager.

Correct, I wanted the highest possible resolution rather than the most recent appearance so most of the Jupiter facing hemisphere is from Voyager data. IIRC Galileo was scheduled to image at least the right half of what's visible in the NH image at fairly high resolution (much higher than Voyager) very late in its mission but went into safe mode.

While trying to match Bjorn's rendered view to the LORRI image, I notice the right hand side (near the terminator) features are way off while the left hand side fits perfectly. It's as though at a single longitude someone ripped off the texture and misplaced it?

Hmm... a part of the right hand side was made from low-res Voyager data IIRC so there may be some positional inaccuracies but some of these differences seem to be due to surface changes between Voyager 1 and NH. I probably need to check my map - the Voyager USGS map I used as a reference when reverse engineering the viewing geometry of the Voyager images may also have been inaccurate (it was based on Voyager data only and also didn't make use of all of the useful Voyager images). No hi-res and useful map incorporating Galileo data was available to me back then but that situation has improved .

[belleraphon1]

All I can say is WWW!!!!!!! (WOW WHATTA WEEK And thank goodness for the internet).

Io AND Titan ..... what a strange solar system we have met...... can't wait for the rest of New Horizon's data
............... cna't wait for Pluto/Charon...................

Craig

[Tom Tamlyn]

I'm surprised that the reference images of Io are still from Voyager rather than Galileo. I realize that Galileo returned only a heartbreakingly small fraction of the high-resolution images of which it was capable, but I would have thought that it repeatedly covered Io at better than Voyager resolution.

I found this helpful page by volcanopele, which maps high resolution imaging, but doesn't address low resolution coverage.

TTT

EDIT: I thought some more about volcanopele's comments and put on my thinking cap. Io is gravitationally locked with Jupiter, and managing radiation levels was a challenge, so I guess most Galileo observations of Io took place outside Io's orbit and thus didn't cover the Jupiter facing hemisphere. [google, google] I'm not finding a handy orbit by orbit summary of the Galileo mission, the sort of thing that Emily does for us now. Did Galileo every observe the pro-jovian hemisphere of Io?

This post has been edited by Tom Tamlyn: Feb 28 2007, 03:35 AM

[tfisher]

Here's a quick flicker gif comparing 4th rock's colorized New Horizon's shot with the Galileo image that volcanopele posted, for the much-resurfaced lower-right quadrant. Sorry for the low quality; I don't have time to reproject this right to get the geometry to match properly, so this is a quick-and-dirty affine transformation to get things close enough to compare. You can see that a lot of the changes we saw from Bjorn's composite are indeed new since Galileo. Using the USGS feature names, it seems that there have been serious changes in the Tarsus Regio, with big changes in the shapes of the Kaki-oi Patera and Masubi Fluctus. Cool!

[volcanopele]

Thought I would take a look into Shango, perhaps the most interesting new lava flow observed in this image.

Here is a view of Shango Patera from Galileo:



The color data is from the C21 encounter in July of 1999, and the higher resolution gray-scale data is from the I24 flyby in October of 1999. Shango Patera, its associated yellow-colored flows, and the near-by mountain, Skythia Mons, are in the zoomed in image at left. Shango Patera was only observed as active once during the entire Galileo mission, as a weak emission source during an SSI eclipse observation. From the looks of the Galileo color image above, it certainly doesn't look active: very little dark material can be seen. The patera is covered mostly in greenish material, the flows appear to be covered in yellow sulfur. The flows looks kinda like the Thor flows in the years before it blew its top in 2001. However, it looks like at some point in the recent past, the patera over flowed, and lava flowed to the south and south west in several, discrete flow lobes

Here is a zoomed in image from NH (with labels):



Again you see Shango Patera, but it is now much darker and has two lobes. The northern lobe I presume is the patera and its immediate surroundings to the south. The southern lobe represents the two southern branches of the associated lava flows seen in the Galileo image (NOT the Southwestern flows). Like Thor in 2001, when Shango erupted, lava followed previously emplaced flows, rather than carving out a new path, though the details of the old and new flows may be different, we just have to resolution to tell. Does that mean that the conduits that fed the south western flows were cut off? A clue can be found in the Galileo images. In the earlier images, bright material surrounded the ends of the southern flows, but not the southwestern flows, suggesting that the southern flows had sublimated sulfur that were then deposited just outside the edges of the flows. Prometheus does the same thing here: http://pirlwww.lpl.arizona.edu/missions/Ga...prometheus.html . This suggests that the southwestern flows have been dormant long enough for both the flows and the flow margins to be covered over in sulfur, while the flow margins (or the SO2 anyways) of the southern flows had not, suggesting that the southwestern flow conduits had been closed off prior to Galileo.

[Exploitcorporati...]

I'm not usually prone to sentimentality(snort), but this has been kind of a remarkable day. I just came to the realization that I will probably not see the volcanoes of Io again in my lifetime after this passage. In the same day, we have a spacecraft orbiting Saturn, three circling Mars and two on the surface, one passing the same and looking through its own sails, one bound for Mercury, one at Venus, and a host of spacecraft on the surface here waiting to set out for Luna and the asteroids and beyond. Seems sorta ridiculous to get ecstatic over two pictures of a flying pizza. I only have two people in my immediate world who even remotely(but very sympathetically) get it. Their eyes still glaze over after five minutes of babbling. Thanks john_s, Alan Stern, volcanopele, and everyone else here for the ride.

X's and Oh!s.

[mchan]

When the moon hits your eye like a big pizza pie, that's amore!

Seriously, I echo your sentiments on these past few days. A "you are there" view on a low Mars flyby, radar and optical views of previously unseen big lakes on Titan, a long anticipated revisit to a dynamic ever-changing Io, continually changing perspectives of the capes of Victoria crater, and the usual weekly offerings from HiRISE. The only comparison that comes to mind of so many new vistas is the Voyager flybys. And that was like going to a movie theatre of the 70's with only one screen. The past few days have been like going into all the auditoriums in a multiplex cinema.

And as Alex is the Reference Librarian, Jason is the Io Tour Guide. Thanks!

[djellison]

Not sure how close to C/A there will be other Io obs, but Io should appear just short of twice that size later today.

Doug

[ugordan]

Will the Pele ring look different in MVIC data?

I didn't think MVIC would even attempt observations of the sunlit side due to its extreme sensitivity. I was under the impression only nightside, jupitershine observations would be done?

[tedstryk]

I didn't think MVIC would even attempt observations of the sunlit side due to its extreme sensitivity. I was under the impression only nightside, jupitershine observations would be done?

I vaguely remember one dayside attempt with MVIC for Io being on the schedule. I think they hoped that it could pull something off in the high phase areas. I hope that some of the LORRI images contain multiple frames that can be stacked. Even if super-resolution doesn't work, it would cut down on noise.

[Littlebit]

EDIT: I thought some more about volcanopele's comments and put on my thinking cap. Io is gravitationally locked with Jupiter, and managing radiation levels was a challenge, so I guess most Galileo observations of Io took place outside Io's orbit and thus didn't cover the Jupiter facing hemisphere. [google, google] I'm not finding a handy orbit by orbit summary of the Galileo mission, the sort of thing that Emily does for us now. Did Galileo every observe the pro-jovian hemisphere of Io?

The Galileo news archive, including weakly status reports, is a pretty good source:

http://galileo.jpl.nasa.gov/news/archive.c...=21&Incr=10


Galileo made several close passes of Io and had a real hard time: Every time the probe approached the moon it balked and dived into safe-mode...edit: well, not quite every time - there was at least one full science pass: http://galileo.jpl.nasa.gov/news/display.cfm?News_ID=1163

[ustrax]

Looks like Prometheus shows up okay in the short exposure too, waaaay stretched:

I grabbed your image and stretched even a bit more...
Man...That's scary!