Bulletin of the American Physical Society
2007 APS Four Corners Section/SPS Zone 16 Joint Fall Meeting
Volume 52, Number 14
Friday–Saturday, October 19–20, 2007; Flagstaff, Arizona
Session C4: Astro: Earth and Solar System |
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Chair: Stephen Tegler, Northern Arizona University Room: Physical Sciences (Bldg. 19) Room 321 |
Friday, October 19, 2007 3:25PM - 4:01PM |
C4.00001: Meteoroids and Meteors: Investigating the Crumbs of Creation. Invited Speaker: Meteoroids are solid objects in space that typically originate from the breakup of comets and asteroids. Meteoroids are of fundamental importance to our understanding of the Earth and our solar system because they are composed of the material from which everything in our solar system was originally made. Outstanding questions include how many meteoroids enter Earth's atmosphere, how much material do they deposit, what is their origin, and what are their densities. When a meteoroid -- typically the size of a grain of sand -- enters into the Earth's atmosphere, it ablates and forms localized plasma near 100 km altitude; the luminous phenomenon associated with a meteoroid's entry is referred to as a meteor. Large-aperture, narrow-beam radars often detect the meteor plasma that surrounds a meteoroid and moves at its speed; these signals are called head echoes. By analyzing head echo data, we can derive fundamental meteoroid properties by modeling the scattering interaction of a radio wave with highly-dense plasma. In this presentation, we will discuss the relationship between meteoroid and head echo plasmas and how we use high-power, large-aperture radar data to analyze both stellar and interstellar meteoroids. [Preview Abstract] |
Friday, October 19, 2007 4:01PM - 4:13PM |
C4.00002: Near-infrared Observations of Saturn's Satellites at True Opposition MIchael Freed, Anne Verbiscer, B. Sicardy, R.G. French, R. Hock The 2005 opposition of Saturn presented the rare opportunity to observe its satellites at the smallest possible phase angles attainable at Saturn's heliocentric distance. Here we present the analysis of observations obtained at Pic du Midi Observatory using Moicam, an infrared imaging instrument mounted on the 2-m Telescope Bernard Lyot during the period 10 - 17 January 2005 at phase angles ranging from $\alpha $ = 0.37$^{^{\circ}}$ to 0.01. Using broadband near-infrared filters JHK, centered at 1.2, 1.6, and 2.2 $\mu $m, respectively, we observed the opposition effect on Enceladus, Tethys, Dione, and Rhea. In addition, observations using the narrowband Paschen beta filter, centered at 1.28 $\mu $m, reveal the opposition effect on Titan and Iapetus. [Preview Abstract] |
Friday, October 19, 2007 4:13PM - 4:25PM |
C4.00003: From Earth to Mars, Radiation Intensities in Interplanetary Space Keran O'Brien The radiation field in interplanetary space between Earth and Mars is rather intense. Using a modified version of the ATROPOS Monte Carlo code combined with a modified version of the deterministic code, PLOTINUS, the effective dose rate to crew members in space craft hull shielded with a shell of 2 g/cm$^{2}$ of aluminum and 20 g/cm$^{2}$ of polyethylene was calculated to be 51 rem/y. The total dose during the solar-particle event of September 29, 1989, GLE 42, was calculated to be 50 rem. The dose in a ``storm cellar'' of 100 g/cm$^{2}$ of polyethylene equivalent during this time was calculated to be 5 rem. The calculations were for conditions corresponding to a recent solar minimum. [Preview Abstract] |
Friday, October 19, 2007 4:25PM - 4:37PM |
C4.00004: Analysis of atmospheric data to measure occurrences of Polar Mesospheric Clouds Shana Coffey, Michael Stevens, Christoph Englert, Dave Siskind Polar Mesospheric Clouds (PMCs) are high altitude (about 80 km) clouds that occur in the summer in the polar regions and are believed to be increasing in brightness over the last hundred years. This recent increase may be related to global climate change, but may also be correlated, in part, to increased shuttle launches. In this talk I will discuss the work of my summer internship at the U.S. Naval Research Laboratory (NRL), where I analyzed the calibrated spectral data of the upper atmosphere from a new type of interferometer, SHIMMER. The SHIMMER interferometer was developed at NRL and, using a new optical technique called spatial heterodyne spectroscopy, can measure with high sensitivity and high spectral resolution over a narrow passband. I used data from SHIMMER to look for PMCs by calculating the integrated spectrum at each altitude of the observed region. The altitude profile was then compared to a model profile of the atmosphere to see if there was an increase of photon scattering at any one altitude. The distribution of PMCs at local solar time will be discussed. Future research will compare the observed PMCs in the northern and southern hemispheres. [Preview Abstract] |
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