New Horizons at Io |
New Horizons at Io |
Feb 24 2007, 07:53 PM
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
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. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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Oct 10 2007, 06:38 PM
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Senior Member Group: Moderator Posts: 3233 Joined: 11-February 04 From: Tucson, AZ Member No.: 23 |
In conjunction with the publication of "Io Volcanism Seen by New Horizons: A Major Eruption of the Tvashtar Volcano" in Friday's New Horizons @ Jupiter special issue of the journal Science, several images have been released based on figures from the paper. The first, located at http://pluto.jhuapl.edu/gallery/sciencePho.../100907_10.html, shows a montage of images taken of the Tvashtar plume, including an HST observation from before the encounter, several high-resolution LORRI views of the plume, and a series of images taken at 2-minute intervals. The LORRI images reveal filamentary structures that can change over a very short period of time as they descend from the top of the plume back down to the surface. The appearance of the plume is consistent with non-ballistic trajectories of the dust particles within the plume (caused by interaction between the dust and gas in the plume) and with the dust being created from condensation of gas at the top of the plume [N.B. the lack of a central eruption column, a la Prometheus].
The second image, located at http://pluto.jhuapl.edu/gallery/sciencePho...s/100907_9.html, shows a montage of eclipse images. Eclipse images acquired by LORRI revealed a number of hotspots caused by active volcanism on the surface, auroral glows (note the glowing atmosphere allowing you to see where the limb is in the eclipse data), and other glows. Included in the "other glows" are fields of bright spots near the sub- and anti-jovian points. Comparing the eclipse data to a visible basemap, these bright spots correspond to volcanoes. Because these spots are not seen by the LEISA instrument, it is thought that these glows are not caused by thermal emission, but are instead caused by gases over the volcanoes becoming excited by Jupiter's magnetosphere. It is still possible that these volcanoes are the site of current or recent volcanic activity, but the thermal emission that produced is either too small or too cool to be detected by LEISA (keep in mind that LEISA does not see as far into the Near-infrared as NIMS did, so older hotspots may not be detected by LEISA. For example, a 200K hotspot, corresponding to a cooled flow that erupted 3.5 years ago (assuming a 10-m thick flow with basaltic composition), might not be detectable with LEISA, but it might lead to an enhancement in SO2, which would be seen in these LORRI eclipse images. The third image, located at http://pluto.jhuapl.edu/gallery/sciencePho...s/100907_8.html details activity on the surface of Io, as plumes, surface changes, and hotspots are marked on this map. Also, the slides from John Spencer's presentation here at DPS yesterday are also available on line. Those are located at: http://pluto.jhuapl.edu/news_center/news/1...essGraphics.htm. -------------------- &@^^!% Jim! I'm a geologist, not a physicist!
The Gish Bar Times - A Blog all about Jupiter's Moon Io |
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