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.

[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:

[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 .