Titan's spectrum and atmospheric composition

Spectroscopic evidence shows that hydrogen atoms are major constituents of Titan's atmosphere. Anomalous enhancement of the methane absorption band is attributed to isotopic shifts arising from methane photolysis. Anomalous ultraviolet absorption features suggest high altitude dust and an elevated cloud layer overlaying most of the methane in the atmosphere

The jovian environment

Jovian atmosphere and environment - composition, structure, and photometric properties of atmosphere, period of rotation, magnetic field, and Jovian radiofrequency spectru

Far Field Deposition Of Scoured Regolith Resulting From Lunar Landings

As a lunar lander approaches a dusty surface, the plume from the descent engine impinges on the ground, entraining loose regolith into a high velocity dust spray. Without the inhibition of a background atmosphere, the entrained regolith can travel many kilometers from the landing site. In this work, we simulate the flow field from the throat of the descent engine nozzle to where the dust grains impact the surface many kilometers away. The near field is either continuum or marginally rarefied and is simulated via a loosely coupled hybrid DSMC - Navier Stokes (DPLR) solver. Regions of two-phase and polydisperse granular flows are solved via DSMC. The far field deposition is obtained by using a staged calculation, where the first stages are in the near field where the flow is quasi-steady and the outer stages are unsteady. A realistic landing trajectory is approximated by a set of discrete hovering altitudes which range from 20m to 3m. The dust and gas motions are fully coupled using an interaction model that conserves mass, momentum, and energy statistically and inelastic collisions between dust particles are also accounted for. Simulations of a 4 engine configuration are also examined, and the erosion rates as well as near field particle fluxes are discussed.Astronom

Seasonal Variability In The Ionosphere Of Uranus

Infrared ground-based observations using IRTF, UKIRT, and Keck II of Uranus have been analyzed as to identify the long-term behavior of the H-3(+) ionosphere. Between 1992 and 2008 there are 11 individual observing runs, each recording emission from the H-3(+) Q branch emission around 4 mu m through the telluric L' atmospheric window. The column-averaged rotational H-3(+) temperature ranges between 715 K in 1992 and 534 K in 2008, with the linear fit to all the run-averaged temperatures decreasing by 8 K year(-1). The temperature follows the fractional illumination curve of the planet, declining from solstice (1985) to equinox (2007). Variations in H-3(+) column density do not appear to be correlated to either solar cycle phase or season. The radiative cooling by H-3(+) is similar to 10 times larger than the ultraviolet solar energy being injected to the atmosphere. Despite the fact that the solar flux alone is incapable of heating the atmosphere to the observed temperatures, the geometry with respect to the Sun remains an important driver in determining the thermospheric temperature. Therefore, the energy source that heats the thermosphere must be linked to solar mechanisms. We suggest that this may be in the form of conductivity created by solar ionization of atmospheric neutrals and/or seasonally dependent magnetospherically driven current systems.STFC PP/E/000983/1, ST/G0022223/1RCUKGemini ObservatoryNational Aeronautics and Space Administration (NASA) NXX08A043G, NNX08AE38AAstronom

Mutual Event Observations of Io's Sodium Corona

We have measured the column density profile of Io's sodium corona using 10 mutual eclipses between the Galilean satellites. This approach circumvents the problem of spatially resolving Io's corona directly from Io's bright continuum in the presence of atmospheric seeing and telescopic scattering. The primary goal is to investigate the spatial and temporal variations of Io's corona. Spectra from the Keck Observatory and McDonald Observatory from 1997 reveal a corona that is only approximately spherically symmetric around Io. Comparing the globally averaged radial sodium column density profile in the corona with profiles measured in 1991 and 1985, we find that there has been no significant variation. However, there appears to be a previously undetected asymmetry: the corona above Io's sub-Jupiter hemisphere is consistently more dense than above the anti-Jupiter hemisphere

Effects of valent image-based secondary tasks on verbal working memory

Two experiments examined if exposure to emotionally valent image-based secondary tasks introduced at different points of a free recall working memory (WM) task impair memory performance. Images from the International Affective Picture System (IAPS) varied in the degree of negative or positive valance (mild, moderate, strong) and were positioned at low, moderate and high WM load points with participants rating them based upon perceived valence. As predicted, and based on previous research and theory, the higher the degree of negative (Experiment 1) and positive (Experiment 2) valence and the higher the WM load when a secondary task was introduced, the greater the impairment to recall. Secondary task images with strong negative valance were more disruptive than negative images with lower valence at moderate and high WM load task points involving encoding and/or rehearsal of primary task words (Experiment 1). This was not the case for secondary tasks involving positive images (Experiment 2), although participant valence ratings for positive IAPS images classified as moderate and strong were in fact very similar. Implications are discussed in relation to research and theory on task interruption and attentional narrowing and literature concerning the effects of emotive stimuli on cognition

Abundances of ammonia and carbon disulfide in the Jovian stratosphere following the impact of comet Shoemaker‐Levy 9

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95648/1/grl8459.pd

Usability and Usage of Interactive Features in an Online Ebook for CS Teachers

There are too few secondary school computing teachers to meet international needs for growing secondary school computing education. Our group has created an ebook to help prepare secondary teachers to teach the programming and big data concepts in the new AP Computer Science Principles course. The ebook was designed using principles from educational psychology, specifically worked examples and cognitive load. The ebook interleaves worked examples and interactive practice activities, which we believe will lead to more efficient and effective learning than more typical approaches to learning programming. This paper reports the results from initial studies of our ebook. First, we conducted a usability study comparing three different ebook platforms. Next, we conducted a study of teacher use of the ebook. Ten teachers worked through the first eight chapters of the ebook at their own pace. Five of the ten teachers completed the first eight chapters which is a 50% completion rate. Significantly, teachers who used more of the interactive features in the ebook did better on the post-tests and reported higher confidence in their ability to teach the material than teachers who used few of the interactive features

Io'S Atmospheric Freeze-Out Dynamics In The Presence Of A Non-Condensable Species

One dimensional direct simulation Monte Carlo (DSMC) simulations are used to examine the effect of a trace non-condensable species on the freeze-out dynamics of Io's sulfur dioxide sublimation atmosphere during eclipse and egress. Due to finite ballistic times, essentially no collapse occurs during the first 10 minutes of eclipse at altitudes above similar to 100 km, and hence immediately after ingress auroral emission morphology above 100 km should resemble that of the immediate pre-eclipse state. In the absence of a non-condensable species the sublimation SO2 atmosphere will freeze-out (collapse) during eclipse as the surface temperature drops. However, rapid collapse is prevented by the presence of even a small amount of a perfect non-condensable species due to the formation of a static diffusion layer several mean free paths thick near the surface. The higher the non-condensable mole fraction, the longer the collapse time. The effect of a weakly condensable gas species (non-zero sticking/reaction coefficient) was examined since real gas species may not be perfectly non-condensable at realistic surface temperatures. It is found that even a small sticking coefficient dramatically reduces the effect of the diffusion layer on the dynamics. If the sticking coefficient of the non-condensable exceeds similar to 0.25 the collapse dynamics are effectively the same as if there was no non-condensable present. This sensitivity results because the loss of non-condensable to the surface reduces the effective diffusion layer size and the formation of an effective diffusion layer requires that the layer be stationary which does not occur if the surface is a sink. As the surface temperature increases during egress from eclipse the sublimating SO2 gas pushes the non-condensable diffusion layer up to higher altitudes once it becomes dense enough to be collisional. This vertical species stratification should alter the auroral emissions after egress.Aerospace Engineerin

Modeling The Vapor And Dust Dynamics Due To The Impact Of The Lcross Spacecraft On The Moon

The implications of possibly large volatile reservoirs on the Moon are significant for the future of manned activity there and for space science and exploration in general. In autumn of 2008 NASA will launch the LCROSS mission to impact two spacecraft into a permanently shadowed crater-a cold trap - at the south pole of the Moon. The lead spacecraft will excavate its own several meter crater. The process will be observed by the following smaller vehicle and by orbiting and Earth-based instruments in hopes of observing the release of volatiles-predominantly water -- from the lunar soil. The following vehicle will then impact as well. We examine the plausible vapor dynamics following the impacts and concentrate on the observability of the gas from Earth or lunar orbit. In the free-molecular computational model of the vapor motion, water and OH molecules move ballistically, have a temperature-dependent surface residence time, and are subject to photo-dissociation and ionization losses. Sunlight shadowing, separation of the vapor from the dust grains, dust thermodynamics and different impact plume models are considered.Aerospace Engineerin