New Horizons at Io Options

[volcanopele]

Since the New Horizons Jupiter Encounter thread is already getting pretty long, I decided to create a thread dedicated to New Horizons' observations of the most interesting object in the solar system: Io. Info on upcoming observations comes from the jupiter_timeline_static.xls document john_s posted, and the preview images are from Celestia (note that each image is scaled so that the pixel scale is ~correct, and represents a smaller FOV than LORRI)

Today, February 24, New Horizons conducts three observations of Io with the LORRI camera as well some observations of Io's atmosphere with ALICE. These observations have the lowest phase angle for Io of the entire encounter. Phase angle continues to increase as NH approaches Jupiter and Io.


The first observation, ISunMon1, shows Io's sub-Jovian hemisphere (Clat=5.5 S, Clon=340.2 W) from a distance of 7,856,307 km. The resolution with LORRI would be 38.8 km/pixel. Pele is on the limb at lower right and Masubi is on the limb at lower left. Ra Patera is near center.


The second observation, ISunMon2, also shows Io's sub-Jovian hemisphere (Clat=5.5 S, Clon=15.1 W) from a distance of 7,575,510 km. The resolution with LORRI would be 37.5 km/pixel. The Tvashtar plume might be poking above the limb at upper left.


The third observation, ISunMon3, shows Io's leading hemisphere (Clat=6.0 S, Clon=84.7 W) from a distance of 6,627,459 km. The resolution with LORRI would be 32.8 km/pixel. The Zamama plume might be visible just above center on the left limb.

It only gets better from here. Not sure how NH downlink works, but there is a DSN window right after the last Io observation, hopefully at least one frame from each observation will be returned. Maybe they can do the Huffman window right around where Io is... Tomorrow contains four more observations of Io, highlighting Pele and an eclipse.

[elakdawalla]

Jason, in case you didn't see it, here's the brand new image of Io from Hubble that John posted on the blog yesterday:

There was more excitement yesterday. We've been turning our Earthly (and near-Earthly) telescopes on the Jupiter system too, to give us the broader context for New Horizons' snapshot of the system. Yesterday Kandis Lea Jessup and I got our first look at the first Hubble pictures of Io, taken back on Valentine's Day (these were the images we had to scramble to redesign at the end of January, after the failure of Hubble's other camera). Io was only 16 pixels across in the pictures, but that was enough to show us something very interesting at ultraviolet wavelengths: there was a huge volcanic plume rising above the edge of Io's disk. We're not yet 100% sure which volcano is generating the plume, but I have a hunch that it's Tvashtar, a volcano that obliged Cassini by producing a similar-sized plume during Cassini's Jupiter flyby in late 2000. We've seen plumes like this in Hubble images before, but they aren't particularly common, so we are excited at the prospect of getting much closer images of this thing with New Horizons next week. In fact the New Horizons schedule includes a color image specifically to look at Tvashtar's plume, on the off-chance that there might be something there to see. We just need Tvashtar (or whatever volcano is actually responsible) to keep doing its stuff for one more week. Credit: John Spencer and Kandis Lea Jessup, Southwest Research Institute, and the Space Telescope Science Institute

--Emily

[volcanopele]

Cool, certainly looks like it could be Tvashtar. Given the viewing geometry, there is a slightly better candidate in an unnamed patera at 61N, 143 W, but given that it was only seen as a hot spot once, Tvashtar would be the better candidate.

[john_s]

More Hubble images now down- the Tvashtar(?) plume continues to be active through at least February 22nd, so there's a good chance that it will be active during the flyby too. Hubble only sees the plume in the ultraviolet, so it's not a sure thing that we'll see it at longer wavelengths with New Horizons, but I think the chances are quite good, particularly after closest approach when high phase angles will make it more visible.

[volcanopele]

That's a good point. Given the phase angles of these early images, it maybe rather difficult to resolve most of the plumes on Io.

[john_s]

Not sure how NH downlink works, but there is a DSN window right after the last Io observation, hopefully at least one frame from each observation will be returned. Maybe they can do the Huffman window right around where Io is... Tomorrow contains four more observations of Io, highlighting Pele and an eclipse.

The only Io images we'll get down before the second week of March are ISunMon09, taken at 8:40 on 2/26, which will be sent down during the downlink immediately following on the 26th, and IHiRes05, taken at 11:00 on 2/28, which will come down during the downlink starting at 15:52 on 2/28. The limitation is as much the time needed to compress the images and prepare them for downlink, given how busy the spacecraft is, as the actual transmission time. Both will show the same hemisphere of Io, centered on longitude ~65, with Prometheus on the limb and Tvashtar also near the limb. I goofed slightly in selecting these two as our early downlink images, given their similar geometry, but there *were* a lot of constraints.

John.

[volcanopele]

Today, February 25, New Horizons conducts three monitoring observations of Io with the LORRI camera focusing on the trailing hemisphere, as well some observations of Io's atmosphere with ALICE and an observation of Io while it is in eclipse with the LORRI, ALICE, and RALPH instruments. As noted in the post above, these observations won't be returned until next month.

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


The first observation, ISunMon5, shows Io's trailing hemisphere (Clat=3.0 S, Clon=225.4 W) from a distance of 5,276,976 km. The resolution with LORRI would be 26.1 km/pixel. Pele is visible at lower left and Prometheus is at center right. If Loki's plume(s) are active, then it *might* be visible at upper left.


The second observation, ISunMon6, shows Io's trailing hemisphere (Clat=3.0 S, Clon=253.1 W) from a distance of 5,217,587 km. The resolution with LORRI would be 25.8 km/pixel. Pele is now just below center and Loki has rotated into view at upper left. Prometheus' plume might be visible at center right, though as noted in the above posts, this might not be the best viewing geometry for observing Io's plumes given LORRI's wavelength range.


The third observation, ISunMon7, shows Io's trailing hemisphere (Clat=3.0 S, Clon=308.1 W) from a distance of 5,184,145 km. The resolution with LORRI would be 25.6 km/pixel. Pele is now visible at lower right. Loki is now visible near center. Not sure where Loki is in its geological clock, but the SNR of LORRI might be enough to allow one to see where the overturn front is in Loki Patera.

The final observation is Ieclipse1, an observation of Io in eclipse. RALPH will be active during the eclipse, allowing for an observation of Io's current volcanic activity. Loki should be easily visible in the LEISA images, depending again on where it is in its geological clock...

[just-nick]

The only Io images we'll get down before the second week of March are ISunMon09, taken at 8:40 on 2/26, which will be sent down during the downlink immediately following on the 26th, and IHiRes05, taken at 11:00 on 2/28, which will come down during the downlink starting at 15:52 on 2/28. The limitation is as much the time needed to compress the images and prepare them for downlink, given how busy the spacecraft is, as the actual transmission time. Both will show the same hemisphere of Io, centered on longitude ~65, with Prometheus on the limb and Tvashtar also near the limb. I goofed slightly in selecting these two as our early downlink images, given their similar geometry, but there *were* a lot of constraints.

John.

Thanks for the inside look at the downlink. As always, the NH team is making us feel like real insiders.

What's the likely turnaround for these images to make it onto the SOC page? I remember things like the MER landings and Deep Impact where the first download images were just popping in right there on NASA TV but also situations like Huygens where there was a lot of stitching and sifting.

And what can we expect from the downlink that just happened?

Incidentally, what sort of compression are you using?

[Exploitcorporati...]

<clink> Tvashtar still has that enormous ring.

[ugordan]

Woohoo, 2 new Io images!

And an eruption! Is that Jupitershine illuminating Io's night side or an internal reflection?

[john_s]

A little experiment on you guys- we posted the images about 40 minutes ago and were wondering how long it would take someone to notice them and spot the plume! We'll be doing a proper press release image in a few hours.

John.

[Alan Stern]

John seems to have a little too much time on his hands, wouldn't you say, gents?

[ugordan]

Yeah, he'd better get that press release done before us guys scoop you!

[Exploitcorporati...]

Damn. Looks like two of them. Didn't notice Tvashtar popping off too!




Edit...oopsie. My monitor washed out ugordon's pic. This is awesome.

[ugordan]

Umm, where do you see the second plume?

[siravan]

Hi eveyone. This is my first post to UMSF. Here is my take on "plume finding" on Io.

[Exploitcorporati...]

I thought I saw one on the center limb. Didn't realize that the Tvashtar plume was clearly visible in your pic.

[john_s]

Good eyes, exploitcorporations! There is a very small plume on the center limb (around 9 o'clock)- that's Prometheus.

John.

[Bjorn Jonsson]

That's spectacular and one can even easily discern the plume's umbrella-like shape. This is not a surprise because with extreme contrast enhancement plumes are visible in some of the low-phase Voyager 1 clear filter images of Io (for example C1636826.IMQ) despite Voyager 1's more primitive camera.

Makes me wonder what the Voyager 1 Jupiter encounter would have been like had the Internet and powerful computers been common back then and if the image release policy was MER/Cassini/NH-like. One thing is certain: The plumes would have been discovered *before* the Io flyby.

[JRehling]

Good eyes, exploitcorporations! There is a very small plume on the center limb (around 9 o'clock)- that's Prometheus.

John.

I see the small one at 9 o'clock, the large hazy one at 11 o'clock, and two small features around 2 o'clock which are either big mountains peeking over the limb or smaller forelit plumes.

[Exploitcorporati...]

Are those a couple on the terminator, too?



edit...sorry, I keep getting out of sequence. kabooom.

[john_s]

Nope, those are mountains on the terminator

[Bjorn Jonsson]

Knowing the viewing and lighting geometry or the *exact* time the image was obtained would be lovely - then I could make a hi-res computer rendering to check what these features near the terminator are...

EDIT: Didn't see John's reply (these are mountains) before I wrote this.

[siravan]

Here is the plume image.

Attached thumbnail(s)

 

[volcanopele]

Note the double ring around Masubi!

GREAT IMAGES, john_s!!!! This is such a good day, for other spacecraft images as well...

[DEChengst]

Great pics, thanks for putting them up so quickly. Hoping for more the coming days

Quick question for John about the lecture you'll be giving tomorrow:

Will it be recorded and put on the web ?

[Exploitcorporati...]

Those mountains look from the map like they might be part of the big complex to the east and northeast of Ukko Patera about 10W 40N.

[ugordan]

Great catch on the 9 c'clock plume, Exploitcorporations! I wrote it off as scattered light/topography, but a little sharpening brings out the nebulosity of the feature nicely.


Bjorn, we already know the time when the image was taken: 2007-02-26 08:40:04 UTC

[remcook]

sorry, but I have to add another wow! happy days

[john_s]

Quick question for John about the lecture you'll be giving tomorrow:
Will it be recorded and put on the web ?

Apparently slooh.com will be trying to do something to broadcast it- they have a 7-day free trial membership.

And siravan's image was interesting, showing the plume in the short-exposure image- I hadn't noticed it in that frame, having concentrated on the long exposure frame. And ugordan's view of Prometheus is better than anything I'd come up with so far. Nice stuff!

John.

[Exploitcorporati...]

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

[DEChengst]

Apparently slooh.com will be trying to do something to broadcast it- they have a 7-day free trial membership.

Too bad that doesn't look like a very good option. For the trial you need to get yourself the most expensive account and cancel within a week. That's something I don't really like, and wouldn't be an option for me anyway, as I don't have a creditcard.

If there's a way you could get me a videoclip of the lecture I'll put up a torrent to share it, and archive it on my webserver later. If that fails I also would be happy with just a sound recording and the slides of the lecture, so I can make a flash movie out off it to share with the world

[Bjorn Jonsson]

Bjorn, we already know the time when the image was taken: 2007-02-26 08:40:04 UTC

I was too excited to notice .

Here is a shaded computer rendering showing the area visible in NH's photo in detail:



And a diagram-like one:


There's something that looks like mountains like the terminator as had been indicated by John.

[volcanopele]

Sorry I have been slacking off on the image previews. I've been sick the last couple of days and today has been extremely hectic at work!

I'll try to get the last two days work up tonight. Nice work everyone on these images that showed up this morning. I've only had a short amount of time to look at them unfortunately.

[lyford]

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

clink clink clink clink

[SFJCody]

I was too excited to notice .

Here is a shaded computer rendering showing the area visible in NH's photo in detail:

Someone should subtract this image from the New Horizons image in photoshop to spot the biggest surface changes.

[hendric]

Wahoo! Great images everyone. You could have a NH pic of the day for the next few months as the rest of them stream down!

[Phil Stooke]

"Someone should subtract this image from the New Horizons image in photoshop to spot the biggest surface changes."

What, like this?

It's a good idea, but Io looks so different in different fliters that it's no use unless the filter matches exactly. However, this is a first look at the question.

A is the big plume deposit - that does look different between old and new images. B is a smaller but real change. There are lots of smaller changes, but they get messed up by the filter issues. Wait for the real data - then it will be possible to do something.

Phil

[stevesliva]

I'm wondering if the big new streak pointing southwest in the lower right quadrant of the new photo is new, or if it just doesn't show up in the low-res chunk of the composite image that happens to be there.

[volcanopele]

Interesting ratio, Phil. Looks like something big happened at Shango Patera

[4th rock from th...]

Here's a processed image from both exposures, with color data from the rendered view. Hope this helps in identifying changes. At least is a nice new Io image!



Some changes are visible :-)

[volcanopele]

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. Check out this view from Galileo:

[Guest_AlexBlackwell_*]

Here is the aforementioned press release.

[ugordan]

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?

[volcanopele]

Yesterday, February 26, New Horizons conducts one monitoring observation with the LORRI camera focusing on the leading hemisphere, two "HiRes" observations with LORRI and RALPH instruments focusing on the leading and anti-Jovian hemisphere, as well some observations of Io's atmosphere with ALICE during a stellar occultation.

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, Iocc1, is a stellar occultation of Io's atmosphere using the ALICE instrument. LORRI will also get a single frame shows Io's leading/pro-Jovian hemisphere (Clat=6.6 S, Clon=35.1 W) from a distance of 4,546,235 km. The resolution with LORRI would be 22.5 km/pixel. The Tvashtar plume should be at its fullest extent at upper left since Tvashtar is right on the limb.


The second observation, ISunMon9, shows Io's leading hemisphere (Clat=7.1 S, Clon=68.2 W) from a distance of 4,085,950 km. The resolution with LORRI would be 20.2 km/pixel. This observation is now on the ground so I don't think I need to discuss this much, but the Tvashtar and Prometheus plumes are visible along the bright limb, and volcanoes such as Lei Zi Fluctus and Masubi are highlighted.


The third observation, Ihiresir1, marks the start of high resolution observations at Io. The observation consists of both LORRI and RALPH frames (to look at Io in color and to examine the current distribution of hot spots). It will show Io's leading hemisphere (Clat=8.6 S, Clon=145.7 W) from a distance of 3,065,158 km. The resolution with LORRI would be 15.2 km/pixel. Prometheus is now front and center from this viewpoint. If Pillan is active, its plume might be visible at left.


The final observation, Ihires1, shows Io's anti-Jovian hemisphere Clat=8.6 S, Clon=145.7 W) from a distance of 2,880,909 km. The resolution with LORRI would be 14.2 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). Prometheus has now rotated over to the right and Pele is now on the limb. *Maybe* its plume will be visible. The Tvashtar image above gives me hope.

[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!

[ugordan]

@Bjorn:

Interestingly, I ran into the same kind of alignment problem when trying to fit a Solar System Simulator image of Europa to the image. I'm starting to think LORRI's pixels aren't perfectly square.

[stevesliva]

Interestingly, I ran into the same kind of alignment problem when trying to fit a Solar System Simulator image of Europa to the image. I'm starting to think LORRI's pixels aren't perfectly square.

Or, Europa's oblate and the simulation is a sphere

[ugordan]

I get differences on the order of >100 km in the equatorial direction for both Io and Europa. They can't be THAT oblate, can they?

From Rotation of Europa:

Europa is a triaxial ellipsoid (a: 1563 ±1 km b: 1561 ±2 km c: 1559.5 ±1 km)

LORRI's ~20 km resolution by far drowns out the ellipsoid shape at these distances.

[Bjorn Jonsson]

@Bjorn:

Interestingly, I ran into the same kind of alignment problem when trying to fit a Solar System Simulator image of Europa to the image. I'm starting to think LORRI's pixels aren't perfectly square.

The Solar System Simulator uses a completely outdated airbrushed map of Europa based on Voyager data only. I wouldn't be surprised if it had large positional errors.

Here is what I get with my Europa map:



Matches the NH image almost perfectly (I will be posting a higher resolution version in a different thread since this is the Io thread). The big question is the Io map - I'm hoping for accurate Voyager Jupiter SPICE kernels to eventually show up so I can make a more accurate version someday...

[volcanopele]

Now back to everyone's favorite moon...

Today, February 28, New Horizons makes its closest approach to Jupiter. There are six observations planned during this closest approach period, including 4 high resolution observation, 2 multi-spectral observations with LORRI, MVIC, and LEISA, and another stellar occultation.

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, Ihires4, shows Io's sub-Jovian hemisphere Clat=6.1 S, Clon=21.6 W) from a distance of 2,692,601 km. The resolution with LORRI would be 13.3 km/pixel. The phase angle has increase substantially since the last Io observation, Ieclipse3, yesterday. Now only a little more than half of Io is illuminated by the sun from this vantage point. However, the portion not illuminated by the sun is illuminated by Jupiter, allowing for Jupiter-shine observations.


The second observation, Ihiresir3, shows Io's sub-Jovian hemisphere (Clat=6.0 S, Clon=25.8 W) from a distance of 2,675,561 km. The resolution with LORRI would be 13.2 km/pixel. Taken only a few minutes after the Ihires4 observation, not much has changed, but now RALPH will be getting in on the action, making multi-spectral observations.


The third observation, Iocc2, is the second of two Io stellar occultations. No LORRI frames are planned, just ALICE observations.


The fourth observation, Ihires5, shows Io's leading hemisphere (Clat=5.7 S, Clon=63.9 W) from a distance of 2,489,864 km. The resolution with LORRI would be 12.3 km/pixel. The phase angle continues to increase, now at 102.3 degrees. The Prometheus and Tvashtar plumes should now be easily visible along the limb. The new Shango Patera flow should also be visible. This observation is already on the ground. Hopefully, we will see it soon.



The fifth observation, Ishine1, show Io's leading hemisphere (Clat=5.5 S, Clon=76.6 W) from a distance of 2,426,086 km. The resolution with LORRI would be 12.0 km/pixel. The phase angle will be 106.6 degrees. This multi-spectral observation is designed to examine the sub-Jovian hemisphere in Jupiter-shine with MVIC and LEISA. Is Shango still active?


The final observation of the day, Ihires6, shows Io's leading hemisphere (Clat=5.4 S, Clon=90.0 W) from a distance of 2,364,560 km. The resolution with LORRI would be 11.7 km/pixel. Prometheus is now rotating into view.

[mgrodzki]

on planetary radio last week, emily mentioned that the color images of the moons would be taken with jupitershine as the color cameras are set to sensitive for the low light at pluto. when do we get to see that? i suspect that there may be a real different look to them in jupiterlight.

[mgrodzki]

volcanopele sort of adressed my question while i was posting it.

[JRehling]

Not all is lost for good temporal coverage of Io's activity:

http://alamoana.keck.hawaii.edu/news/archive/io/index.html

Of course, we see "demonstration" images without a lot of regular follow-up. I don't know what it would take to get an Earth-based monitor of Io's activity working "around the clock", but it seems like it would be cheap compared to a mission, and since only one or two images would need to be taken per day, that leaves a lot of observation time for other targets.

Sure, the IR bands look weird, but they're better for watching the eruptions than visible light.

Webb will obviously excel for all of these purposes, but won't devote too much of its time to Io per se.

I think Earth-based observation without gaps remains an exciting possibility for Io, but I don't know whose money would pay for that.

[Guest_John Flushing_*]

on planetary radio last week, emily mentioned that the color images of the moons would be taken with jupitershine as the color cameras are set to sensitive for the low light at pluto. when do we get to see that?

Not right away. By my understanding, the images will have to be stored on flash drives for a while before they can be beamed to Earth.

[mgrodzki]

it would seem so… damn, they should have been planning a jupiter probe ten years ago.

[paxdan]

BBC report about the "massive 150 m, 495 ft high plume" on Io.

*sigh*

[ugordan]

^^^ Mega LOL at that.

[paxdan]

So I checked, and the BBC story said it was "Last Updated: Thursday, 1 March 2007, 08:24 GMT". I must've read it at almost exactly the time of the last update because i fired of a correction to them (with a link to the original JHUAPL press release) before making my post above at 8:30 am.

From the auto response:

Comments about our stories or services will be passed on to the appropriate editor. Factual or spelling errors will be corrected.

I wonder how long it will take to correct?

[general]

It has been corrected

Attached thumbnail(s)

 

[ugordan]

WOW!!! Tvashtar's Plume!


Check out the third plume from Masubi at 6 o'clock, on the night side but reaching into sunlight!
Amazing, simply amazing.

[volcanopele]

COOL! Looks like their are two plume sources at Masubi.

[ugordan]

Could we be seeing another plume at around 5:30 on the limb? There's some suspicious fuzzyness there.

[volcanopele]

Could we be seeing another plume at around 5:30 on the limb? There's some suspicious fuzzyness there.

I noticed that too. Can't be sure just from this image, hopefully we can say for sure when the rest of the images come down.

Some thing to look for. Good Eyes!

[ugordan]

Here all the visible plumes as well as my candidates for additional discrete plumes so far:

The Tvashtar eruption seems like a double plume.

[volcanopele]

Good eyes.

With out a lat-lon grid this is difficult to assess, but I'll give it a stab. Let's assume for a moment that those bumps at 5 o'clock and 5:30 are real features (they might be, they might not be, difficult to say). The bump at 5:30 might be a plume associated with the volcano Aramazd Patera. The bump at 5 o'clock I think is the mountain Euboea Montes.

[ugordan]

The 5:30 feature definitely makes for a more convincing case than the 5 o'clock one. You're probably right on it being a mountain. The Tvashtar plume either got a weird twist or there's also something else erupting there.

[Bjorn Jonsson]

WOW!! This may be the most dramatic image I have ever seen of Io's plumes. And not unexpectedly, LORRI is very sensitive - does anyone know the strength of Jupitershine on Io's nightside as compared to sunlight at Pluto?

And here is a rendering showing the viewing geometry:

[Stu]

Hands up confession time... I've never really been that excited by Io (ducks to avoid slapping hand of volocanopele! ) but wow, that image is a stunner... the detail in that plume is just incredible.

Imagine what that would have been like in colour...

[ugordan]

After closest approach, Io's quickly reduced to a waning crescent, allowing for longer exposures. While the resolution will rapidly diminish, we should be able to see numerous plumes crop up in scattered light and jupitershine. And likely with some (low resolution) color, too!

What a great week!

[TritonAntares]

...

...
Amazing, simply amazing.

Really picturesque. Impressive what NH cameras can achieve with the dark Io-hemisphere in jupitershine.
Makes us hope for Pluto and Charon - even if it's much darker out there!

Btw., there are some mensae visible at the terminator, here a nice close up of such mountains imaged by Galileo:


Bye.

[Stu]

[john_s]

Imagine what that would have been like in colour...

Patience- there will be colo(u)r! We got a lower-resolution color scan with MVIC at the same time, but it won't be sent down for a month or more. We'll do some cool colorization then, I'm sure.

John.

[dilo]

Great colorization, Stu!!!
Waiting for the full picture...
(sad to think we will not see such kind of images for a while, even if with the most advanced AO telescopes the particular geometry/lighting which make possible to see such volcanoes and mountains aren't possible from Earth!)

[Bjorn Jonsson]

Here is a properly shaded version with exaggerated Jupitershine showing at higher resolution what's visible in the NH image. As discussed when the first Io images appeared some changes are visible.

In addition to a texture map I used a crude elevation map where I 'manually' painted in all of Io's major mountains using a table from a paper published in Icarus (or possibly JGR - I'm too lazy to check) several years ago as a guide. In addition to the table I also used various images as a guide. This now seems to have been more successful than I thought although various 'errors' can be spotted. Various mountains and mesas are obvious near the terminator.

[Stu]

[volcanopele]

For the mountain lovers, here's a graphic labeling all the mountains, except for the little guy northeast of Gish Bar Patera.

[Guest_AlexBlackwell_*]

John S. has a nice new glog entry.

[Exploitcorporati...]

Thanks, VP! Io's mountain landforms are strangely more fascinating to me than the volcanoes, but I'm biased in favor of tall stuff.

Here's a link to Schenk and Hargitai's database project for anyone interested:
Io Mountain Database

Nice work on the colorized pic, Stu!

edit: The lighting geometry on the Hi'iaka Montes looks very similar to that seen on Galileo's passes.

[tfisher]

Here's another take on the changes at Masubi since Galileo. Comparison again is to the Galileo frame that volcanopele posted, flipping back and forth with the latest new LORRI frame. It looks like the current Masubi eruption is spewing primarily from what used to be that corner bend of Masubi Fluctus, with maybe some secondary plume(s) to the east.

[tfisher]

Here's my take on colorization of the latest image, using Bjorn's view for hue and saturation and using the shorter exposure raw images to add some more detail in the overexposed sunny side:

[volcanopele]

You have to be kinda careful about colorizing high-phase Io images. Io's colors can change quite dramatically as you increase phase angle.

BTW, thanks for pointing out that the raw images are now up, including the shorter exposed images of Io.

Here is the 4 msec exposure image with Shango Patera pointed out:

[ustrax]

artifact or another plume?

[remcook]

is this above-average activity on Io or are there always 3 or more volcanoes activily spilling their guts? Amazing little moon

[ugordan]

I'd say it's always pretty active. Maybe not huge volcanoes such as Pele or Tvashtar, but smaller ones, yes. And Io's not that small a moon either!

[Ant103]

A "seven error game"


The image of the left comes from Celestia, I've desatrured it and darken the night side to have a good model comparison.
The differences are very small...