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]

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.