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The Planetary Society BlogBy Emily Lakdawalla39th annual meeting of the Division of Planetary Sciences is next weekOct. 5, 2007 | 11:28 PDT | 18:28 UTC
Next week is the 39th annual meeting of the Division of Planetary Sciences of the American Astronomical Society, which is usually abbreviated to just "DPS." I'll be wrenching myself away from the baby to attend the first two days of it, all the way across the country in Orlando. I've now surveyed the program and it's packed. As always there are plenty of Cassini results to cover; there's also lots of news from both ground-based and space-based observatories studying asteroids, comets, and the Kuiper belt. This year is bringing the Uranian equinox, so there are many interesting presentations on that, and there have also been quite a few stellar occultations by Pluto to yield information about its size, shape, and atmosphere. The YORP effect was directly detected for the first time, and Mars Reconnaissance Orbiter and the Mars Exploration Rovers are picking apart Mars' chemistry and studying this year's dust storm in detail. I'll do my best to cover a broad sampling of the sessions and report on them here, and will see if I can get a few other people to contribute some notes from sessions I can't attend.
At the same time as Enceladus is a session starting with Io and ending with Mercury for some reason. The Mercury talks include a presentation by Cecil and Rashkeev on their Earth-based observations of the side of Mercury not seen by Mariner 10. A third session details Jovian meteorology. Later in the morning, in a session on the interiors of giant planets, Gerald Schubert delivers an update on the question of Saturn's rotation. There's a whole session devoted to the YORP effect. YORP stands for Yarkovsky, O'Keefe, Radzievskii, and Paddack, all of whom studied the effects of solar radiation pressure on small bodies in the solar system. The overview talk by Paddack and Rubincam should be helpful. Other papers discuss the three detections, just published in the last year, of YORP effects, on asteroids 54509 YORP (Lowry et al. and Taylor et al.), 1862 Apollo (Kaasalainen et al.), 25143 Itokawa (Kitazato et al.). A couple more interesting overview talks (William Bottke and Jean-Luc Margot) close the session.
At lunchtime there'll be a town hall meeting chaired by Dave Lavery on some new technologies for space exploration that are coming out of NASA's Planetary Science Division. Monday afternoon begins with concurrent sessions on Saturn's rings, NEO searches, and giant planet atmospheres. The rings session includes updates on Cassini CIRS (Spilker et al.) and radio science (Marouf et al.). A couple of other papers explore the rings' origins -- are they primordial (Stewart et al.) or are they a disrupted Centaur (Dones, Agnor, and Asphaug)? This is a question I get a lot for Planetary Radio so I'll be sure to check out their answers. Finally, Esposito and Elliott explore what the surface compositions of ring particles mean for the history of the ring system.
In the giant planet atmospheres session at the same time, there are a couple of Saturn talks followed by a bunch of stuff on Uranus, which is near its equinox. The most interesting talks cover Hubble (Erich Karkoschka) and radio telescope (Hofstadter, Butler, and Gurwell) and Palomar Adaptive Optics (Bauer et al.) observations. Rings topics continue into a second afternoon session. Several presentations treat the enigmatic "propellers" in Saturn's A ring (Seiss et al., Sremcevic et al., and Tiscareno et al.), and several more look at the confusing structure of the F ring (Meinke, Esposito, and Colwell; Charnoz et al.). Hedman et al. look at some Saturnian rings that show heliotropic behavior -- they're farther away from Saturn at noon than at midnight. Makuch, Schmidt, and Spahn study where in the ring system Enceladus' ejected particles end up. Finally, the session wraps up with two talks on the Uranian ring plane crossing from ground-based observatories (de Pater et al.) and Hubble (Showalter et al.) Up against the second ring session is a "Satellite Potpourii." There's interesting-looking talk on craters on Ganymede (Barlow and Godwin) and on Saturn's satellites (Dombard et al.). Elder et al. look at a strange diffuse band covering the equatorial region of Tethys' leading hemisphere. Matson, Castillo-Rogez, and Johnson wonder about Rhea's shape. Thomas et al. consider a few diverse Saturnian satellites and try to explain their surfaces. Clark et al. will talk about Dione's surface as seen by Cassini VIMS.
Later in the morning is a special session on New Horizons at Jupiter. Many of these presentations will no doubt be similar to ones given at the icy satellites workshop in September, but there are some that were not covered there: Baines et al. on Jovian meteorology and Showalter et al. on the rings, among others. At the same time is a session on Mars' weather, including a presentation by Cantor et al. on MOC and MARCI observations over the last five years; Kass et al. on the dust storm as seen by MCS; and Lemmon et al. on the dust storm as seen by the rovers' Pancams. Tuesday afternoon begins with the prize lectures. Andy Ingersoll received the Kuiper prize in recognition of outstanding contribution to planetary science; he'll speak on giant planet atmospheres. Francis Nimmo received the Urey prize, recognizing outstanding achievements by a young scientist, and will talk about the geodynamics of icy bodies. There are usually three prize lectures, but it appears the Sagan award, recognizing outstanding communication by a planetary scientist to the general public, is not being awarded this year.
In the afternoon, attention turns to formation of planetary and satellite systems and the detailed compositions of asteroids. The poster session covers future missions, asteroids, comets, Saturn's atmosphere and icy moons, trans-Neptunian objects, Mars' surface and interior, and planetary formation. There is a poster by Rita Schulz on the detailed science plans for the September 2008 flyby of asteroids 2867 Steins by Rosetta, and an overview by Conrad et al. on the decade of contributions of the Keck II telescope to planetary science. Trilling et al. describe 35,000 asteroids serendipitously detected in Spitzer data. Bowles et al. deliver an update on the Martian dust storm from Mars Climate Sounder. West et al. show SAR imaging of Iapetus. On Thursday morning is a comet session. Belton and Drahus find that activity in comet Tempel 1's northern hemisphere is accelerating its spin, which is obviously important for planning the flyby geometry of the Stardust NExt mission (which will re-visit the Deep Impact target comet in 2011). At the same time is a Titan session. Lopes et al. open it with a description of Titan geology. Hayes et al. describe the northern lakes. Perry et al. reprise the talk given at the icy satellites conference on Titan's trailing hemisphere. Wood et al. assert from RADAR data that Xanadu is not a high-standing continent, as it appears; instead, it's a low-lying, ancient piece of land (I'm curious how they explain the apparent lack of impact craters). Barnes et al. say that VIMS can detect Titan's dunes whenever VIMS gets better than 1-kilometer spatial resolution (corresponding to a flyby closer than 2000 km, in their low-resolution mode), and that the dune sand is either solid organics or ice with a several-micron-thick coating of organics. At the same time as the comet and Titan sessions is one on Venus chemistry, which is bracketed an opening talk by Sean Solomon on early results from the June 5 flyby by MESSENGER and a closing talk by Håkan Svedhem on the status of Venus Express. Later Thursday morning are sessions on Titan's atmosphere and on comet comae.
At the same time is an asteroid session with many talks on near-Earth objects, including an update on the impact risk from Alan Harris, which includes the reassuring conclusion that "The impact risk from NEAs smaller than 1 km diameter is several times less than previously estimated." Giorgini et al. update us on the specific hazard from Apophis. Stern et al. report on using STEREO data to search for Vulcanoids, finding none. After that is the Thursday poster session, with posters on asteroids, Pluto, trans-Neptunian objects, comets, Uranus, Titan, and Venus. On Friday morning, there's a Pluto system session in which many of the talks cover new results from the July 31, 2007 stellar occultation by Pluto. The stellar occultation permits scientists to probe two main topics: Pluto's diameter, which is, oddly enough, not known as precisely as Charon's diameter is (see E. Young, L. Young, and Buie) and Pluto's atmosphere, both its current state and how it has been changing over time as Pluto recedes from the Sun (see Sicardy et al; Pasachoff et al.; L. Young et al.). Also, a couple of people report on Pluto and Charon's composition (Protopapa et al.) and observations of basic characteristics of Nix and Hydra (Sicardy et al; Buie, Grundy, and Tholen; and Tholen, Buie, and Grundy). Friday afternoon features a Titan session including some atmospheric stuff and four papers by members of the RADAR teams on Titan's spin state (Stiles et al.; Lorenz et al.) and Radio Science (Del Marmo et al.; Asmar et al.). From Earth we can't measure Titan's spin particularly accurately because of the atmosphere. Cassini's radio instruments have measured it much more precisely, strongly suggesting the presence of an interior ocean, as predicted. In between the atmosphere and interior papers is a rather randomly located one by Davies et al. describing how fast a Titan cryolava flow should lose its heat to the atmosphere and solidify. At the same time as the Titan session is one on the Kuiper belt. Among many papers on the orbital structure and dynamics of the Kuiper belt, there's a rather sensational one by Lykawka and Mukai suggesting that the sharp outer edge to the Kuiper belt is caused by a tenths-of-Earth-mass planet that orbits at roughly 100 AU.
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