LOL, yeah, I just noticed that in the caption. Makes sense, explains why you can see surface features only in the Tvashtar region, not anywhere else.

WOOHOO! More images. Io images even!

Quick look results:

*Plume at Shango Patera Not a plume, actually Skythia MonsI am so lost, that's a plume, but it is at Amirani...
*Prometheus flow hasn't changed shape since the late 2001
*Prominent plume deposit around new lava flow at 58 South, 295 West (northern Lerna Regio). Plume no longer active (not apparent in LORRI images)

Click to view attachment

The first image set up is Ihires1. These images were acquired on Feb. 26, 2007 at 21:01 UTC. The images were acquired from a distance of 2,881,000 km and have a resolution of 14.2 km/pixel. The individual frames shown are (clockwise from upper left): a 4-msec exposure, a 20-ms exposure, a preview image from Celestia, and a 75-msec exposure.

The 4-msec exposure image reveals the albedo features visible across Io's anti-Jovian hemisphere. The persistent volcano Prometheus is visible just right of center. No major albedo changes are apparent. The plume deposit around Thor has faded from its appearance in August 2001, but the lava flows associated with Thor have not yet faded back to its pre-eruption appearance. The plume at Prometheus may have moved, creating a double ring appearance to the west of the plume source, but that maybe a phase angle effect. There was a brightening of a small region north of Volund.

The 20-msec exposure highlights the mountains visible near the terminator. The most prominent mountains include Euxine Mons (the N-S trending mountain south of Tvashtar), Capaneus Mensa (the mitten-shaped plateau south of Emakong Patera, and a plateau in the south polar region, south of Telegonus Mensae/Bactria Regio.

The 75-msec exposure highlights three plumes: Tvashtar (the prominent one in the north polar region), Amirani (visible just past the terminator southwest of Euxine Mons), and Masubi (south polar region along the dark limb).

EDIT 04/04/07: On further inspection, I found a darkening at a patera located at 56 South, 157.5 West, south of Mycenae Regio.
EDIT 04/04/07: Nevermind, that is likely to be a phase angle effect at the patera there.

Click to view attachment

The next image set up is Ihires2. These images were acquired on Feb. 27, 2007 at 01:05 UTC. The images were acquired from a distance of 2,691,000 km and have a resolution of 13.3 km/pixel. The individual frames shown are : a 3-msec exposure, a 20-ms exposure, and a preview image from Celestia.

The 3-msec exposure highlights albedo features on Io's anti-Jovian hemisphere. The most prominent albedo feature is Pele at lower left. The prominent red ring of Pele appears to be more extended to the southeast than during its previous appearances in the latter part of the Galileo mission. No other major surface changes are apparent, though I should note that the apparent darkening of the flow I mentioned in a previous post, appears to be caused by a phase angle effect (the old flow appears to be strongly forward scattering), as the flow doesn't appear darker in this image than similar phase angle images from the Galileo I32 flyby.

The 20-msec exposure highlights topographic features (and albedo features for that matter) near the terminator. Not many mountains are visible, though Tohil Mons and a mountain east of Shamash Patera can be seen southeast of Culann Patera. Plumes should also be faintly visible in this exposure. The top of the Tvashtar plume is visible. No other plumes are visible. A plume over the new flow at 58 South, 295 West should have been visible in this image along the limb at lower left had it been active and/or the exposure supported its visibility.

Click to view attachment

The final image set up is Ihires3. These images were acquired on Feb. 27, 2007 at 09:15 UTC. The images were acquired from a distance of 2,679,000 km and have a resolution of 13.3 km/pixel. The individual frames shown are : a 3-msec exposure, a 20-ms exposure, and a preview image from Celestia.

The 3-msec exposure highlights albedo features on Io's trailing hemisphere. The most prominent albedo feature in this image is Pele, the ring of red material below and to the right of center. I discussed Pele in the last post so I won't go over that again. Unlike the last couple of posts, there are a few major surface changes representing eruptions that have occurred since October 2001. The most prominent is a new dark lava flow centered at 58 South, 295 West. This flow is located along the northern margin of Lerna Regio, a bright region within Io's south polar region. This flow is surrounded by a bright material that appears to have a greater extent, particular to the north, than the bright material associated with Lerna Regio, indicating that this bright material is from this new eruption. Surrounding this new bright deposit is a partial ring of dark material, probably representing a new red ring deposit. Dazhbog Patera continues to remain prominent, 6 years since the major eruption in late 2000, and has not faded from its pre-eruption appearance, though its plume deposit may have (similar to the situation of at Thor). There is a new dark flow to the east of Dazhbog Patera, located at 51 North, 278 West. An old flow is visible there in the Galileo and Voyager imagery, so like Thor and Tvashtar, this maybe a volcanic center that uses the same channels over and over again.

The 20-msec exposure highlights topography near the terminator. Among the mountains visible are Ionian Mons (northeast of Pele), Ot Mons (southeast of Ionian Mons just past the terminator), and a mountain just past the terminator in the south polar region in western Illyrikon Regio.

Because not everyone is caught up on their Ionian geography, here are some labeled images:

Click to view attachmentClick to view attachmentClick to view attachment

Marchis et al. 2005 reported that a hotspot was observed at the flow labeled "New Flow #2" on December 28, 2001. This hotspot was observed using the Keck telescope's Adaptive Optics system. The authors state that this eruption may have started between the 23rd and 28th since the hotspot was not observed on the 23rd.

Getting the impression here that buying real estate on Io would be risky indeed... ...is there any part of the moon that is not subject to sudden, unexpected volcanic activity? In other words, are there geological districts that are thought to be relatively stable, such as near those tremendous mountains (what's holding them up? )

Actually, on or near mountains would be one of the worst places to build settlements on Io due to the avalanche risk. Most mountains on Io show signs of significant mass wasting, suggesting that they may not be all that stable.

The non-volcanic plains, like Colchis Regio, maybe the best places to put settlements. We haven't really seen new volcanic centers form in the 28 years that volcanoes have been monitored. This suggests to me that settlements within non-volcanic plains could be stable for quite a long time.

And I have narrowed down the date of the northern Lerna Regio eruption. It appears to have been a bright hot spot on July 15, 2005, as observed by the Marchis group working with Keck AO.

Just Beatiful!
I was playing around with the original image and found it curious that "something" appears always on a precise location, Marduk I guess (help me here volcanopele...) but I can't distinguish anything in particular in the original image...
Here it goes:
Click to view attachment

Okay, with two eruptions seen by Keck tied to surface changes, I thought I would check on an outburst observed by Marchis et al. on May 28, 2004. Their hotspot was located at 17.5 South, 6.3 West (with error bars of +/- 5 degrees) and was one of the brightest hotspots observed on Io during the interprobum. This eruption was attributed to either Angpetu Patera or Ilmarinen Patera. So, I thought I would look through the New Horizons images to see if there was a visible surface change.

First, let's take a look at the eruption site in Galileo images for context. The first image below is c0420669000r from the 11ISTOPO__01 observation. The second image is the same image, but I have labeled some of the volcanic centers seen in the observation to provide some context. The area marked 0405A is the center of the error box given by Marchis et al. for the May 2004 eruption. This spot is located in the northwestern part of the Tung Yo Fluctus lava flow, an old flow first observed by Voyager. However, keep in mind that box that the hotspot could be located in includes Angpetu, Sui Jen, and Ilmarinen Paterae.

Click to view attachmentClick to view attachment

Okay, so what do the New Horizons images show? Unforunately, the longitudes close to the sub-Jovian point have the poorest sunlit coverage during the New Horizons encounter. I've attached versions of the two online image sets that provide coverage over this eruption site: ISunMon2 and Ihires5. Looking at these two observations, it would seem that there was no surface change associated with the 0405A eruption, indicating that either the surface changes have faded since 2004, the change were small compared to other eruptions like in northern Lerna Regio, and/or there was no visible surface change associated with the eruption, akin to the Tupan eruption from March 2003, suggesting an interpatera eruption.

Click to view attachmentClick to view attachment

Stealing an idea from Emily, here is an animated gif of the Io images returned thus far showing Ionian albedo features, i.e. the short exposure images. Click on the link above for an animated gif of Europa images.

EDIT: New image added 04/04/07
EDIT: Three new images added 04/07/07
EDIT: Two new images added 04/16/07
EDIT: New image added 04/23/07
EDIT 05/01/07: Movie removed. See http://www.unmannedspaceflight.com/index.p...ost&p=89403 for updated versions.

Oh, you beat me to it, Jason!

--Emily

Click to view attachment
http://pluto.jhuapl.edu/gallery/missionPho...ges/040207.html

Another MVIC color view of Io (and Europa) as released by the New Horizons team. This color view is one of the Kodak moment views timed more for their aesthetic potential than for scientific reasons, though obviously a lot of science can be obtained from views like these.

Click to view attachment

The above composite compares the MVIC view to the Celestia simulated view. When you stretch the MVIC image you can make out several major albedo features in Jupiter-shine, such as Shamshu, Kanehekili, Eastern Media Regio, and Tarsus Regio. You can also see three plumes: Tvashtar, Prometheus, and Amirani. In the methane filter, you can make out the Tvashtar hotspot as well as a red spot south of Gish Bar Patera. Is this potentially another hotspot, or just a noise hit?

Click to view attachment

This is cutout from the Galileo C21 global color mosaic of Io showing the region containing this potential hotspot. No volcanoes are seen where the hotspot are located though the closest matches are Gish Bar and two unnamed paterae. I don't think these are close enough though to explain this spot, so I would go with noise hit for this spot.

So that again brings up the question: where are the other hotspots? And just how hot is Tvashtar that it is the only hotspot you can see in images like these??

Congrats to hendric, John, and Alan for a cool image!

Jason, is the USGS map of Io that just showed up on Photojournal actually new, or is it an older release that has just been added late?
http://photojournal.jpl.nasa.gov/catalog/PIA09257

--Emily

The descriptive text does not show up on a Google search, so it's new to the net, at least.

There's other nice new (NH) stuff in the Photojournal's Jupiter gallery, for various places in the Jupiter system. A week of rain after years of drought as far as Photojournal Jupiter content goes.

It is the basemap that the USGS has been working on for a few years now that was finished last year IIRC. This is similar to the maps produced for Callisto, Ganymede, and Europa that came out a few years ago.

The map was released in a way last year as part of the the USGS Planetary Nomenclature site:

http://planetarynames.wr.usgs.gov/images/io_comp_color.pdf

Attached are colorized versions of the three latest LORRI images to be posted on the New Horizons site. Luminosity comes from the New Horizons images, color information comes from a Galileo-only color basemap.

Click to view attachmentClick to view attachmentClick to view attachment

EDIT 04/04/07: Updated third image.

Wow! Lookin' great, Jason, but for some reason the third thumbnail (rightmost) isn't loading...works when you click on it, though.

EDIT: Never mind; it loaded successfully on the third try, you might've been still messing with it.

That's sort of hazardous using an old color map, isn't it? That'd be the first thing to change, no?

In many ways, you're right, one certainly shouldn't derive any conclusions from these colorized images. But at the same time, I was curious how combining the two data sets would turn out and I think they came out looking good, though I think some of the polar color became muted a little. But still, I think it was a useful exercise.

VP, did you use the Lab colorspace or something else? I've noticed a bit of a peculiarity in that colorspace in that it does not (at least in Photoshop) separate luminance from chrominance completely, you can have zero luminance and apply some color to it and it will give you a nonzero brightness and color in RGB space. This makes applying lower resolution color data on luminance data with sharp contrast have color fringing at the edges, not very neat.

To create these colorized images, I reprojected a Galileo-only color basemap to the same geometry as the New Horizons image. I opened up both images in Photoshop. I then pasted the LORRI image on to the Galileo image, creating an image with two layers, one for each image. I used Free Transform to rotate the Galileo image since the New Horizons images don't have north straight up but slightly to the right. Once the Galileo and New Horizons images were aligned, in the Layers palette, I selected the New Horizons image and from the drop-down menu there, I selected Luminosity. I think this has a similar effect to using Lab, but this way I can properly align the images before merging the two. The only problems I have are that the color in some places can become muted, and others, like near the terminator, they can become enhanced because of the short exposure times reduces the dynamic range near the terminator.

Which reminds me, I need to correct the alignment of the third image I posted. I need to rotate the color image to better match the NH view. I'll try to do that tomorrow.

EDIT 04/04/07: I've gone ahead and fixed that third image so you shouldn't see any odd color fringing near features like Loki.

A few posts ago, I talked about my search for surface changes at an outburst observed in May 2004. My brief search came up negative, the area around where the hotspot was observed appeared unchanged since it was last observed in August 2001.

I think I may have found a reason why, or a least a precedent in this area, from Geissler et al. (2004). In June 1999, a bright hotspot was observed in this area by ground-based observers. During C21, on July 3, 1999, a large lava flow was observed surrounded by a large (apparently) red ring (see below, first image set). This red ring faded in a little over a month, and was barely seen during observations taken during C22 (second and third attachment below). This suggests that volcanic deposits in this region quickly fade, so that despite the bright outburst only a few years ago, little trace remains.

Click to view attachmentClick to view attachmentClick to view attachment

Click to view attachment Click to view attachment

A new image set was posted on the LORRI raw images page. These images come from the Ihiresir2 sequence taken on February 27 at 05:38 UTC. They were acquired from a distance of 2,645,000 km and have a resolution of 13.1 km/pixel. The individual frames shown are (clockwise from upper left): a 4-msec exposure, a 20-ms exposure, a preview image from Celestia, and a 75-msec exposure. The second image above is a composite of the 4-msec exposure LORRI image and a Galileo-only color basemap.

This image was taken about midway between the Ihires2 and Ihires3 sequences. Again, the two largest visible surface changes include the dark lava flow and surrounding bright deposit and partial red ring in northern Lerna Regio and a dark lava flow east of Dazhbog Patera. Two other surface changes are visible, including the brightening of the floor of Pillan Patera (though the lava flows from the 1997 eruption remain dark) and a possible brightening in northern Lei-Kung Fluctus.

The 20-ms exposure image reveals several mountains along the terminator including Dorian Montes, Rata Mons, the mountain west of Donar Fluctus, and a mountain in the south polar region.

The 75-ms exposure image shows the Tvashtar plume, partly in shadow.

EDIT 04/05/07: After flipping through Simonelli et al. 2001 last night, you can cross the stuff in northern Lei-Kung Fluctus out as a surface change, and maybe Pillan...not sure yet.

be careful of merging Galileo color with LORRI images. it may be useful as guide but many of those color deposits have changed.

Absolutely. To be honest, they are more for aesthetic purposes than anything else. It's good to hear that you guys are seeing changes in the color images because I only count a handful from the LORRI images (Shango, Tvashtar, N. Lerna, E. Dazhbog, Pillan, Thor, Kanehekili, and Masubi). [EDIT: oh, and Prometheus]

BTW, if anyone else is looking around for surface changes, be very wary about phase-angle effects. While they are not as dramatic as the brightness reversal between the bright equatorial plains and the dark polar caps seen in high phase angle images, they are out there. They even show up when comparing these fairly moderate phase-angle LORRI images to low-phase Galileo images, like the bright deposits surrounding Dorian Montes and Marduk and the bright stuff southwest of Pele.

Okay, I think I figured out what we are seeing at Pillan, we are seeing both a surface change AND a phase-angle effect. In LORRI images of Pillan, the patera floor appears bright and the lava flow from the 1997 eruption appears dark. So, it would appear that Pillan has brightened since 2001 when it was last observed, indicating that the floor of Pillan Patera is now covered in a layer of SO2 frost.

Now, Galileo saw a bright Pillan Patera floor as well, prior to the eruption. The second image I've posted shows two views of Pillan, the first image from the G1 orbit and the second image from the G2 orbit. Initially, this was attributed to lava being emplaced on the patera floor in the 3 months between observations (or thermal emission from the subsurface burning off the SO2 frost layer), but on the subsequent encounter, C3, the floor was bright again. So what was going on? The G1 and C3 images was taken at a moderate phase angle while G2 image was taken at a low phase angle. Apparently, a thin, transparent layer of SO2 frost covered the floor of Pillan Patera, making the floor appear dark at low phase angles. At higher phase angles, sunlight reflected off the coarse SO2 frost grains, making the patera floor appear bright. This scheme went away following the 1997 eruption as the patera floor was too warm for SO2 deposition from the Pele plume. Pillan Patera remained warm throughout the rest of the Galileo mission, again preventing SO2 deposition.

However, it would appear that Pillan has finally quieted down, and a thin SO2 frost layer has been deposited. Like in the early part of the Galileo mission, at low phase angles Pillan should appear dark (though from looking at earlier NH images of Pillan, its floor still appears bright) and at higher phase angles, it appears bright.

Click to view attachmentClick to view attachment

Click to view attachment

Three new image sets were posted online today, filling in some of the gaps in the New Horizons imaging sequence at Io (see the new movie that I have updated with these latest images). The first image set comes from the ISunMon7 sequence taken on February 27 at 14:55 UTC. They were acquired from a distance of 5,184,000 km and have a resolution of 25.6 km/pixel. The individual frames shown are: a 3-msec exposure, a 20-ms exposure, and a preview image from Celestia.

The 3-msec exposure image shows albedo features on Io's trailing hemisphere. Most of the terrain seen here was covered in the higher resolution Ihires3 image sequence, so there isn't much new to cover. A simple comparison between the two image reveals several changes due to the difference in phase angle between the two observations (11.7 deg. vs. 39.4 deg.). One surface change that has become apparent in this image sequence is at Creidne Patera, a dark spot visible at lower left. This feature was seen in the companion Ihires3 observation nearer to the limb. Voyager saw this feature at around 700 m/pixel and saw the northern half of this patera covered in dark lava flows and the southern part coated in orange sulfur. The flows had faded in most Galileo images and Creidne was barely visible as a bright spot southeast of Euboea Fluctus in images taken in August 2001. Now, the caldera, at least the northern part, has darkened significantly. This darkening may be tied to an eruption at Creidne in 2004. Keck AO observations from May 28, 2004 revealed a hotspot with a temperature of 380 K covering more than 1500 square km, suggesting that a cooled lava flow from an eruption with earlier that year. So once again, we can tie a surface change on Io to an eruption observed from Earth in the last 5 years.

The 20-msec exposure is intended to highlight topography near the terminator (though the low phase angle may hide topography) and plumes along the limb. No plumes are apparent.

Click to view attachment

The next image set posted today is Ihiresir1. These images were acquired on Feb. 26, 2007 at 18:38 UTC. The images were acquired from a distance of 3,065,000 km and have a resolution of 15.2 km/pixel. The individual frames shown are (clockwise from upper left): a 4-msec exposure, a 20-ms exposure, a preview image from Celestia, and a 75-msec exposure.

The 4-msec exposure image highlights albedo features on Io's anti-Jovian hemisphere. This observation is very similar to the Ihires1 observation taken 3 hours later, so aren't a lot of differences to mention that weren't covered before. The visibility of some features like Amirani, Tvashtar, and Prometheus are a little better in this view so those maybe worth discussing. No changes are apparent at Amirani, though the northern part of the flow field may have faded some since it was last seen. At Prometheus, I am a little confused as to what is going on there, so the following is just one possible interpretation. The western flow field hasn't moved since we last saw it in 2001, but there have been changes in the central and eastern portions of the Prometheus flow. As shown in high resolution images from Galileo, bright SO2 frost surrounds the western flow field, but unlike in 2000, bright SO2 frost also surrounds the eastern portion of the flow field and has covered the caldera and the southeastern "bump" in the flow field from 2000 in bright frost. Much of bright frost that covered the terrain between the eastern and western flow fields has darkened. At Tvashtar, which is dominated by two general depressions, a shallow apple-shaped western caldera and an NW-SE elongated eastern caldera surrounded on three sides by mesas, both of the two large paterae appear to be covered in dark material (a combination of lava and pyroclastic deposit). A smaller caldera at the center of the eastern patera erupted last April and the large, western caldera appears to be responsible for the current eruption.

The 20-msec exposure image highlights topography near the terminator. Albedo features near the terminator are also a little clearer, such as Amirani. Several mountains are visible such as Skythia Mons, two mountains NE of Shango Patera, Monan Mons, and Telegonus Mensae.

The 75-msec exposure image highlights plumes visible near the limb. The only two plumes visible are Tvashtar and Masubi (lower right, on dark limb). Pillan, if it were active, would also be visible, but it isn't.

Click to view attachment

The last image set posted today is Ihires4. These images were acquired on Feb. 28, 2007 at 3:50 UTC. The images were acquired from a distance of 2,693,000 km and have a resolution of 13.3 km/pixel. The individual frames shown are (clockwise from upper left): an 11-msec exposure, a 20-ms exposure, a preview image from Celestia, and a 75-msec exposure.

The 11-msec exposure image reveals albedo features on Io's sub-Jovian hemisphere. The most prominent of these features is Tarsus Regio with Masubi Fluctus running through the southern portion of this bright region. This flow is the source of at least one on-going volcanic plume visible in numerous images taken by New Horizons. The image shows the plume deposit from Masubi a little clearer that in prior, low-resolution images, though the high-phase angle makes interpretation a little more difficult. In low-resolution images, the plume deposit looked double-lobed, perhaps from two adjacent plumes on Masubi Fluctus. In this image, it looks as if the plume deposit is only visible on the southern and eastern side of the flow.

The 75-msec exposure image reveals two volcanic plumes at Tvashtar and Amirani.

Magnificent, is all. Thanks for posting these, VP. You've just about convinced me that a dedicated Io orbiter should be at the top of the prioritization pile...what a world!

Actually, unless we see a radical improvement in radiation-hardened technology, the last thing I want to see is an Io orbiter. Such a mission would have way too short a lifetime (2 weeks, maybe) to accomplish the kinds of science goals that we want. As mentioned in other topics, it would be better to have a Jupiter-orbiting spacecraft that would repeatedly flyby Io. Such a mission could last 2 years assuming you use the same kind of radiation-hardened technology planned for the current baseline Europa mission (90-day orbital nominal mission).

I keep wondering on the engineering "strategy" of building a mini-Hubble as an outer planets spacecraft.

By that, I don't mean s miniaturized hubble telescope, but a spacecaft that would be essentially a 1 meter or 1.5 meter telescope. Imagine a cassegranian (as a visual example, though we'd probably want all reflecting optics) telescope in a 1-axis fork-mount. The BASE of the mount would be the main spacecraft bus and the BIG X/Ka or whatever band antenna to Earth. ALL of the high power remote sensing instruments would be in bays behind the main mirror, like the instruments on Hubble, with the highest resolution camera at the center of the focal plane pickoff point.

The vehicle's normal mode of operation would be Hubble-like... Instruments all pointing in one direction, but not necessarily overlapping fields of view (unless you can use dichroic mirrors to split (for example) visible and near-IR from thermal IR, etc and share the same fileld of view). The whole telescope could slew toward and away from the beam-angle of the antenna (usually toward the Earth) with one degree of freedom, while spacecraft rolls along the antenna-axis would take care of aximuth pointing.

Use of big photon-grabbing light-bucket optics will give spectrometers a far better tradeoff on area resolution and spectral resolution and signal-to-noise ratio than with Voyager/Galileo/Cassini dedicated instruments, while the sheer diffraction limited resolution increase of the big optics will give the spacecraft the ability to leisurely do whole hemisphere high resolution (kilometer to 100 meter) mapping at 10 times the range of Galileo or Cassini, and permit a Cassini like mission to take frame-filling long range monitoring images instead of of the 50 to 100 pixel icy satellite images it can currently take.

Small, secondary instruments, like Wide-Angle cameras or extreme-ultraviolet spectrometers can be mounted "parasitically" on the main telescope, like finder scopes on a Celestron or the like.

My question is to what extent has mission designs like this been considered compared to the sorts of things we're flying now, with or without scan platforms, with or without near continual telemetry to Earth. What are the drawbacks to such a design, what are the advantages?

I note the currently active thread on an asteroidal "grand tour" multiple flyby encounter mission. A spacecaft built around a telescope like my above idea would have the ability to do high resolution full rotation movies of asteroids during the approach and flyby, in color, and the ability to to substantial hyperspectral imaging of an entire hemisphere during "late far encounter" before fields of view and available time shrink to sample-mapping during close encounter.

It would also be possible to get random "Ann Frank" type (stardust mission) untargeted encounters with enough resolution to show morphology and gross geologic configuration of a sample of asteroids during a long mission, something (as we are seeing) is impossible except by pure luck with untargeted flybys on a Cassini or New Horizons type mission.

Yes, of course, my bad; I actually meant exactly what you wrote, a Jupiter orbiting S/C designed to study Io as its primary scientific goal.

Here are the three latest sequences colorized. Again, take the color with a grain of salt, it is a few years old after all compared to the NH data:

Click to view attachmentClick to view attachmentClick to view attachment

I've also attached a ratio image between Ihiresir1 and a Galileo green filter basemap. Mostly, this map shows differences in albedo due to the difference in the phase angle between the images that make up the basemap (~4 deg) and the NH image (36 deg). However, this does highlight the changes at Prometheus (near center). Most of the changes are phase angle related (the brightening of the outer SO2 ring, the darkening of the inner SO2 ring), but the inner brightening and the innermost darkening/brightening are due to apparent changes in the Prometheus flow field and the SO2 halo immediately around the two main flow lobes. Now, this isn't apparent in the ratio image, but I am beginning to suspect from blinking the Galileo and NH images that the eastern flow lobe now extends further to the east. However, there is a mesa immediately to the east of Promtheus so I don't know what to think anymore.

Click to view attachment

cool, VP!

Here is the completed version of that very crude map I posted yesterday:

Click to view attachment

Volcanopele -- awesome. Thanks for sharing with us here.

Very nice, VP - I couldn't resist doing a bit of ad hoc seam removal on it:

Click to view attachment

Phil

That's sweet, Phil. Is there any "scientific" method you use to equalize the brightnesses on the seams or is that painstaking handwork?

Or a secret, magic recipe?

Three wings from bats, five magnolia leaves, five grams of soil from East Moline, Illinois, and roots from an oak tree - presto you have your map.

*sigh* Science ain't what it used to be...

Or it has gone back to what it used to be (alchemy)

My seam removal was pure hocus-pocus, only done for esthetic effect. I did it in Photoshop. For each seam I selected (using the polygon tool) an area surrounding the seam and extending about half way into the image area on each side. I feathered the outline of the selection, copied it amd pasted it over itself. Then I used the polygon tool again to trace down the seam exactly, and cut off one side of that new layer. Let's say the side I left was the dark side. Now I could brighten that layer, and also darken the background layer (the bright side of the seam) within a feathered selection, until they matched. Any artifacts right on the seam were removed with the 'dust and scratches' noise filter.

It's not science, it's art!

Phil

You can also use soil from Rock Island, but the final product might not look as good.

Hi Folks-

We've been slow about posting new images on the New Horizons web site lately (we're concentrating on a batch of releases for the post-Jupiter press conference on May 1st), but here's a new one, an MVIC color image showing the night side of Io illuminated by Jupiter:

http://www.pluto.jhuapl.edu/gallery/missio...ges/041607.html

Click to view attachment

John.