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Seminars (for Scientists) Fall 2011

Gas Giants

(Courtesy NASA)

Below is the schedule of LASP Seminars for Scientists for the Fall 2011 semester. Most dates and speakers will be finalized within one week of the seminar, so check this site often for the most current information. All LASP seminars are open to the public EXCEPT those labeled “internal.”

LASP Seminars for Scientists are generally on Thursdays from 4:00-5:00 p.m, with refreshments served at 3:45 p.m. Seminars at LSTB (in the East Campus Research Park) are in the main auditorium, room 299, while the seminars at the on-campus Duane building are in room D-142 unless otherwise noted.

For seminars at Duane, parking passes are available for the Euclid parking lot.

For more information or if you have questions contact Sebastian Schmidt: 303-492-6401 or firstname.lastname@lasp.colorado.edu.


Fall Semester 2011 Schedule:

November 10, 2011

Mars Chloride-Bearing Materials – Signatures of Aqueous Environments

Speaker: Mikki Osterloo
Time: 4pm (refreshments served 3:45pm)
Location: Duane Physics Bldg Room D-142
Abstract: The Thermal Emission Imaging System (THEMIS) on the 2001 Mars Odyssey Spacecraft has provided thermal infrared (IR) spectra of materials dispersed throughout the low albedo Noachian and Hesperian-aged southern highlands plains units that show a featureless slope towards longer wavelengths. Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) visible/near infrared spectral observations for the sites indicate that they are composed of a relatively high albedo anhydrous material, which lacks distinct spectral absorptions. Supported by additional observations such as elevated thermal inertia, location in topographic lows, and distinctive morphology (e.g., light-toned and polygonally fractured), there is compelling evidence for a mineralogical component of chloride salt within the materials. Results of our global survey of THEMIS IR daytime data indicate there are hundreds of local exposures spread throughout the southern highlands plains units. Although these chloride materials may only be representative of relatively short-lived bodies of water, such as the salt pans of Death Valley, the fact that the hydrologic and climatic conditions permitted their formation is important and indicates that many locations throughout the southern highlands must have been substantially warmer and wetter in the past. I will discuss the results of our survey investigating the geologic context of the materials, highlighting the materials’ geologic diversity and prevalence across the southern highlands. Additionally, I will discuss our ongoing efforts to investigate and characterize the proposed chloride-bearing materials and their potential formation mechanisms, including crater age-dating of the materials, detailed stratigraphic investigations, and structural analyses of the polygonal fractures identified within many of the sites. Understanding these materials has implications for the hydrological history of the planet and can provide clues to the evolution of regional and global climate.
November 3, 2011

Mars Climate Change and the 2013 MAVEN Mission to Mars

Speaker: Bruce Jakosky, LASP
Time: 4pm (refreshments served 3:45pm)
Location: LSTB
Abstract: There is abundant evidence that the ancient Martian climate was different from the present one. Liquid water was present, leaving behind both geological and geochemical evidence. But the present climate is cold and dry, unable to support sustained liquid water at the surface. I’ll discuss the evidence for climate change and the processes that might have played a role in changing the atmosphere. And I’ll discuss the upcoming Mars Atmosphere and Volatile EvolutioN (MAVEN) mission that will explore the loss of gases from the upper atmosphere to space as a driver of climate change. That mission is in full development right now, and launches in just over two years. It will orbit the planet and, during its one-year-long primary mission, will make measurements that will help us to understand the current composition and structure of the upper atmosphere, the current rates of escape of gas to space, and the extrapolation to earlier epochs. Thus, we will be able to determine the total loss to space over time and the role that loss to space has played in the history of the Martian atmosphere.
October 27, 2011

Two-dimensional Hall MHD reconstruction of a reconnection event in the magnetotail

Speaker: Wai-Leong Teh , LASP
Time: 4pm (refreshments served 3:45pm)
Location: Duane
Abstract: In collisionless space plasmas, the Hall physics plays a significant role in magnetic reconnection. In this talk, I will show the evidence for the Hall electromagnetic field for a reconnection event seen by Cluster in the magnetotail. And I will talk about the newly developed reconstruction method, which is used to produce 2-D maps of field and plasma of the structure observed by a single spacecraft. Using the reconstruction results from Cluster observations, I will show the evidence for the Hall current loops responsible for generating the out-of-plane Hall magnetic field during reconnection. In addition, some interesting results from the maps are also discussed.
October 20, 2011

Improving Radiometry for Climate Studies

Speaker: Greg Kopp, LASP
Time: 4pm (refreshments served 3:45pm)
Location: LSTB
Abstract: How well do we know how much energy is coming in to the Earth’s climate system? And — although a much more difficult measurement — how much of that is lost to space?Climate-quality data require more stringent measurement accuracies and stabilities than needed for shorter-term studies. LASP is helping improve the measurements of both the Earth’s incident and reflected radiation via new radiometric instruments. A 33-year spaceborne record of total solar irradiance, the dominant energy driving the Earth’s climate system, has created a climate data record needed for understanding the influences of the Sun on climate. Instrument and calibration improvements are making these the most accurate and stable radiometric spaceborne measurements in existence, as needed for climate studies. Atmospheric water vapor and other greenhouse gases, aerosols, land use, and several additional natural and anthropogenic influences affect the absorption of this incoming shortwave solar energy and can be inferred from accurate outgoing Earth radiance measurements. I will discuss the status of shortwave radiometry for climate studies, including recent progress improving solar irradiance measurements, new understandings of the accuracy of the existing 33-year record, the resulting estimated climate sensitivities to solar variability, and effects of the recently lost Glory mission on this data record, as well as methods of improving radiometric accuracies on future climate missions to benchmark the Earth’s outgoing shortwave radiation.
October 18, 2011

Multi-Model Comparisons of the Sensitivity of the Atmospheric Response to the SORCE Solar Irradiance Data Set

Speaker: Katja Matthes, University of Potsdam
Time: 4pm (refreshments served 3:45pm)
Location: LSTB
Abstract: Uncertainties in the solar irradiance could have a large impact on simulations of the climate system, since the response of the atmosphere strongly depends on the spectral distribution of the solar irradiance. Most (chemistry) climate models today use the standard NRLSSI (Lean) spectral variability to study the effect of the 11-year solar cycle on climate. However, recent measurements for example from the SORCE-SIM instrument show a completely different spectral distribution than expected, with possible implications for solar heating and ozone chemistry. A number of different sensitivity experiments with 2D and 3D chemistry climate models using the SIM spectrally resolved solar irradiance data will be compared to study the response of the atmosphere. The response to the standard NRLSSI data set will be compared to the new SORCE/SIM measurements. We will focus in particular on the shortwave heating rates, temperatures, ozone and circulation changes. The comparison of the response in a number of different models allows us to better understand the models’ sensitivity to the spectral distribution of the radiation and will help to estimate uncertainties in using the standard solar irradiance data set in the CMIP5 simulations.
October 13, 2011

Planetary Mission Field Tests: Attempts to Maximize Scientific Return

Speaker: Brian Hynek , LASP
Time: 4pm (refreshments served 3:45pm)
Location: Duane Physics Bldg, D-142
Abstract: Earth provides a testbed for fine tuning crewed and robotic mission concepts prior to their launch. I have been participating in several NASA-funded projects that assess the scientific return from various mission scenarios. For example, last month we assessed the potential for quality science data for a proposed crewed landing on an asteroid. In this test, the mission was run from Mission Control at Johnson Space Center while the planetary rovers and astronauts were conducting extra-vehicular activities on lava flows in northern Arizona. Obviously, the surface of an asteroid is quite different than Arizona, but we were able to test operational constraints such as time-delayed communications, bandwidth issues, and limited mobility on low-g surfaces in terms of their impacts on science return. In a different study, we tested the scientific utility of robotic operations of the lunar surface in glacial moraines in Alaska. Finally, I will discuss our pursuits in working with prototype instruments that will be destined for planetary surfaces in the coming years. This includes working in active volcanoes to test a prototype of a mineralogy instrument that is on the 2011 Mars Science Laboratory and also novel high resolution imaging systems for future planetary rovers. The talk will discuss the advantages and disadvantages of various mission concepts and instruments and our efforts to maximize scientific return when they eventually fly.
September 29, 2011

Dynamical Surprises in Saturn’s Rings

Speaker: Glen Stewart, LASP
Time: 4pm (refreshments served 3:45pm)
Location: Duane
Abstract: Imagine what it would be like to observe a “protoplanetary” disk at a resolution of one kilometer over a time span of a 1000 orbits. The Cassini spacecraft has been observing the Saturn system at close range for the past 7 years. During this time, Saturn’s rings have been found to be more complex and time-variable than had been surmised after the Voyager flyby missions 30 years ago. Some highlights of the Cassini observations and their dynamical interpretation will be described. In particular, the rings appear to be marginally gravitational stable, so that the rings break up into high and low density regions and are therefore inhomogeneous on nearly all scales. The effective viscosity of the rings is dominated by gravitational interactions between elongated clumps of particles and exhibits a non-Newtonian rheology. Narrow ringlets perturbed by nearby moons are subject to negative diffusion where particle collisions act to decrease the width of the ring. The total mass of the rings is still poorly constrained, but will be directly measured by the Cassini spacecraft at the end of its mission.
September 15, 2011

Enceladus and its Subsurface Ocean

Speaker: Sascha Kempf, LASP
Time: 4pm (refreshments served 3:45pm)
Location: LSTB
Abstract: Saturn’s ice moon Enceladus turned out to be one of the most intriguing bodies in the solar system. Data returned by several instruments on the Cassini spacecraft provide compelling evidence that this moon is unusually active and is capable of maintaining a pronounced ice volcanism. In particular, measurements of the spatial distribution of the plume particles recorded by Cassini’s dust detector CDA provided the first evidence for a local source of ice grains in the moon’s south polar terrain.Data returned by the neutral gas spectrometer INMS, the UV camera UVIS, and images by the Cassini camera lead to the surprising conclusion that the plume particles are expelled more slowly than the water vapour from the moon’s interior although the grains were expected to be tightly bound to the gas flow within the vents. By assuming that the grains’ motion is strongly affected by collisions withthe vents’ walls, a model proposed by Schmidt et al. matches all plume data available so far. The most important conclusion of this model is that the temperature at the bottom of the cracks must be 260K or higher, suggesting the possibility of a subsurface water reservoir. The discovery of a ring particle population rich on sodium salts, which can arise only if the plume particles are formed from liquid water, strongly supports the existence of a large liquid water reservoir in contact with Enceladus’ rockycore. Composition data obtained during a close Enceladus flyby in 2008 revealed that 99% of the ejected solid material are sodium-rich slow particles, while Saturn’s E ring is dominantly replenished with fast sodium-poor dust grains
September 8, 2011

IBEX

Speaker: Dave McComas
Time: 4pm (refreshments served 3:45pm)
Location: Duane
Abstract: The Interstellar Boundary Explorer (IBEX) mission has been remotely observing the global interaction of our heliosphere with the local interstellar medium for over two and a half years. Initially, IBEX generated the first all-sky maps of Energetic Neutral Atoms (ENAs) emanating in from the boundaries of our heliosphere over the energy range from ~0.1-6 keV. Using these observations, the IBEX team discovered a smoothly varying, globally distributed ENA flux overlaid by a narrow “ribbon” of significantly enhanced ENA emissions. Since the initial publications of these results in a special issue of Science magazine (November 2009), IBEX has completed four more energy-resolved sets of sky maps and discovered small but important time variations in the interaction, separated the ribbon from globally distributed ENA fluxes, measured the energy spectral shape and inferred ion source temperatures, and carried out many other observational and theoretical studies of the outer heliosphere. In addition, IBEX made 1) the first observations of ENAs produced by backscatter and neutralization of the solar wind from the lunar regolith, provided the first energy and angle resolved ENA images of the 1) subsolar magnetosheath, 2) magnetospheric cusps, and 3) terrestrial plasma sheet. New, direct IBEX observations of Interstellar Neutral (ISN) He atoms show that the speed and direction (the motion of the heliosphere with respect to the interstellar medium) is different than that thought from prior Ulysses observations. These observations also show evidence for a previously unknown and unanticipated secondary population of Helium. In addition, IBEX is providing the first direct quantitative measurements of the ISN H parameters and the first direct measurements of interstellar Ne and the interstellar Neon/Oxygen abundance ratio; this ratio is significantly different than the solar abundance ratio. Finally, IBEX was recently maneuvered into a unique, long-term stable orbit, which has a very low radiation environment and requires no orbit maintenance. Thus, IBEX will likely continue to provide revolutionary observations of numerous heliospheric, magnetospheric, and planetary phenomena for many years to come!
September 2, 2011

Space Science Applications for Polypyrrole-based Particles

(Friday) Speaker: Steve Armes, University of Sheffield, UK
Time: 4:00-5:00 p.m. Refreshments served at 3:45
Location: LSTB-299
Abstract: Polypyrrole is an air-stable organic conducting polymer. It can be easily prepared in the form of microscopic particles or alternatively deposited as an ultrathin overlayer on either polymer latex particles or mineral grains. Its conductivity is sufficiently high to enable the efficient accumulation of surface charge and hence acceleration of such colloidal particles up to hypervelocities (1 to 38 km s-1). Thus polypyrrole-based particles are useful for space scientists interested in mimicking the behaviour of micro-meteorites (a.k.a. cosmic dust). Synthetic mimics for carbonaceous, silica-rich or sulfur-rich micro-meteorites have now been designed and specific examples will be discussed in this seminar.
August 29, 2011

Seminar cancelled due to the disruption of flights by Hurricane Irene.

The MESSENGER Mission: 325 Orbits of Mercury and Counting

(Monday) Speaker: Ralph McNutt, Johns Hopkins University, Applied Physics Laboratory
Time: 11:45 a.m.-12:45 p.m. Refreshments served at 11:30
Location: Duane D-142
Abstract: NASA’s MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft is now well into its primary mission to initiate a new era in our understanding of the innermost planet. MESSENGER became the first spacecraft to orbit Mercury on 18 March 2011. MESSENGER’s Mercury Dual Imaging System is acquiring a global monochrome image mosaic at better than 90% coverage and at least 250 m average resolution, a global color image mosaic at better than 90% coverage and at least 1 km average resolution, and global stereo imaging at better than 80% coverage and at least 250 m average resolution. Higher-resolution images are also obtained of pre-selected targeted areas. The elemental remote sensing instruments are being operated nearly continuously and will ascertain the average abundances of most major elements. The Visible and Infrared Spectrograph channel of MESSENGER’s Mercury Atmospheric and Surface Composition Spectrometer (MASCS) is acquiring a global map of spectral reflectance from 300 to 1450 nm at a range of incidence and emission angles. Targeted areas have been selected for spectral coverage into the ultraviolet with the Ultraviolet and Visible Spectrometer, which is also being used to obtain observations of Mercury’s exospheric neutral species via their emission lines. MESSENGER’s Mercury Laser Altimeter is acquiring topographic profiles when the slant range to Mercury’s surface is 1500 km, encompassing the northern hemisphere. Topography over most of the southern hemisphere will be derived from stereo imaging, radio occultations, and limb profiles. MESSENGER’s radio science experiment is ascertaining Mercury’s gravity field from Doppler signals during downlinks MESSENGER’s Magnetometer is measuring the vector magnetic field at an instrument sampling rate of 20 samples/s or in a triggered burst mode to capture magnetospheric when downlink collection is limited. During each spacecraft orbit, the Energetic Particle Spectrometer measures energetic electrons and ions, and the Fast Imaging Plasma Spectrometer measures the energies and mass per charge of thermal plasma components, both within Mercury’s magnetosphere and in Mercury’s solar-wind environment.

Past Seminars