Below is the schedule of LASP Science Seminars for the Fall 2010 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 science seminars 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 more information or if you have questions contact:
- Sebastian Schmid
- email: firstname.lastname@example.org
Spring Semester 2010 Schedule:
|Jan 14||Greg Kopp (LASP)||Solar Incoming and Outgoing Radiometry for Climate Studies
While greenhouse gases are critical in climate studies, the main driver of Earth’s climate – by nearly a factor of 10,000 – is the incident total solar irradiance, which LASP is and will be measuring with the Total Irradiance Monitor instruments on the SORCE, Glory, and NPOESS missions. Water vapor and other greenhouse gases, aerosols, land use, and several additional natural and anthropogenic influences affect the absorption of this incoming energy and can be inferred from Earth outgoing radiance measurements that LASP is working toward acquiring on NASA’s future CLARREO mission.
I’ll discuss how LASP measurements are contributing toward improving the total solar irradiance data record and its relevance in estimating climate sensitivities, and describe a concept for a hyperspectral instrument having improved radiometric accuracy to benchmark the Earth’s outgoing shortwave radiation for future climate studies.
|Jan 21||Alexis Palmero Rodriguez
(Planetary Science Institute, Texas)
|Characteristics of the Martian Cryolithhosphere in Zones of Outflow Channel Occurrence
Previous workers have suggested that chaotic terrain formation on Mars occurred in zones of elevated hydraulic head within a global hydrosphere.Our results indicate that chaotic terrain formation in the region of southern circum-Chryse may have resulted from the disruption of thick sedimentary deposits that contained large numbers of buried impact craters. The presented model suggests that these craters were surrounded by dense fracture systems formed during the impact events, and that both the impact crater cavities and their peripheral fractures may form zones of elevated concentrations of volatiles within the cryolithosphere. Overlapping systems of subsurface fractures and craters would have provided extensive systems of highly permeable upper crustal materials enabling distal groundwater migration into the chaotic terrains and the outflow channels, and accounting for the observed patterns of subsidence that extend beyond the margins of chaotic terrains. In addition, non-emergent thrust faults underlying wrinkle ridges may have also been zones of high permeability and aquifer formation. Formation of subsurface cavities filled with volatiles produced by melting of the permafrost and density differentiation (lithics settling relative to the volatile phase) may have also contributed to increasing the degree of subsurface interconnectivity. In summary, our work regarding the Martian cryolithosphere-hydrosphere system is indicative of an important control of tectonic fabrics on the patterns and magnitude of groundwater migration and emergence. In addition, volatile distribution appears highly heterogeneous. These results are consistent with more recent work that SUPPORT a compartmented hydrospheric system on Mars (Andrews-Hanna et al., 2007; Coleman et al., 2007; Harrison and Grimm, 2009).
|Jan 28||Tom Ayres (CASA)||The Solar Oxygen Problem: Crisis, Catastrophe, or Opportunity?
Over the past decade, the recommended solar oxygen abundance has declined rather precipitously, from a high of 850 ppm in the late 1970’s to the current value of around 450 ppm. At the rate of decline since 2001, in fact, the Sun will run out of oxygen circa 2016. Some might call this as a crisis. Indeed, certain elements of the solar community view the new low oxygen abundance as a catastrophe, because it ruins the previous excellent agreement between theoretical envelope models of the Sun and internal sound speed profiles derived from seismic measurements at the surface. Others see the solar oxygen problem as an opportunity: to test the limits of our ability to extract meaningful fundamental properties from our nearby star. If solar physicists can’t agree on solar abundances, our darkside colleagues will be somewhat limited in their ability to judge whether stellar abundances are normal or unusual. In this talk, I will review the evolution of the solar oxygen abundance over the past three decades, and describe several recent breakthroughs that have helped remove previous glaring disagreements between molecular and atomic tracers of oxygen in the Sun. At the same time, inexplicable differences persist between the two major groups currently pursuing the oxygen problem, reminding one of the two distinct camps in the 1970’s and 1980’s promoting factor-of-two different Hubble constants, demonstrating that “cultural” factors in science sometimes can be as important as hard evidence.
|Feb 4||Delores Knipp (HAO)||Enhanced Thermospheric Density: The Roles of East-West and Northward Interplanetary Magnetic Field
During 2005 solar EUV energy input to the thermosphere waned as Solar Cycle 23
The new Poynting flux estimates suggest that the origins of some disturbances are poorly specified by ground indices. In particular we find that intervals of enhanced northward Interplanetary Magnetic Field (IMF) combined with strong east-west components of the IMF allow significant electromagnetic energy input into localized dayside regions of the high-latitude thermosphere. In some cases this energy deposition is consistent with IMF-geomagnetic field merging tailward of the Earth’s magnetic cusps. In other cases the energy is deposited in the vicinity of an extremely narrow convection throat. This mode of interaction provides little energy to the magnetotail; and instead concentrates the energy in the dayside thermosphere. The extreme localized energy flux also appears to be associated with unusual ion upflows. I will discuss examples of poorly specified neutral density enhancements and their likely sources.
|Feb 11||No Seminar|
|Feb 18||Gerd Baumgarten, Leibniz-Institute of Atmospheric Physics, University of Rostock, Germany||Joint ATOC/LASP seminar
Active and passive remote sensing of the Mesopause region: What do we learn from observing NoctiLucent Clouds (NLC)
Active remote sensing by lidar allows to study processes in the middle atmosphere from small (<1km, 5min) to medium scales (6h) and deliver reliable observations to investigate year to year fluctuations of the atmosphere. Due to the rather complicated instrumental setup only a few lidars are capable of sounding the mesosphere. Especially the polar summer mesopause region offers astonishing processes, e.g. the mean temperature is more than 60K below radiative equilibrium, although the sun is permanently above the horizon. NLC, forming in this region, are a visual manifestation of the extreme state of the atmosphere. These clouds give a very strong signal and can be seen even by eye from ground, although the vertical optical thickness is only about 10-5. Nevertheless from 1018 photons (~100 MW peak power) emitted by the laser only a few are recorded by the detectors. As lidars deliver information only in a small sounding volume the combination with observations from the polar mesosphere cloud imager (CIPS) on the AIM satellite allows to study the dynamics in the mesopause region on larger horizontal scales. Applying state of the art groud based imaging allows to study dynamical processes in NLC extending satellite and lidar observations to extremely small horizontal and temporal scales (<100m, 1sec). Instrumental aspects of lidars, observations and scientific results will be presented.
|Feb 25||Bill McClintock (LASP)||Exploring Mercury’s Surface-bound Exosphere With the Mercury Atmospheric and Surface Composition Spectrometer: Results from the Three MESSENGER Flybys
The planet Mercury is surrounded by a tenuous surface-bounded exosphere whose composition and structure are controlled by interactions among the surface, magnetosphere, solar wind, and sunlight. One of the scientific goals of the MErcury: Surface, Space Environment, Geochemistry, Ranging (MESSENGER) mission is to understand the nature of those interactions in order to identify the important volatile species on or near Mercury and to determine their sources and sinks. MESSENGER is a NASA Discovery-class mission designed to orbit and explore the planet Mercury and its space environment. Launched on August 3, 2004, the spacecraft has flown past Mercury three times (M1 on January 14, 2008, M2 on October 6, 2008, and M3 on September 30, 2009) on its way to orbit insertion on March 18, 2011. It carries a suite of seven miniature scientific instruments. Included among them is the Mercury Atmospheric and Surface Composition Spectrometer (MASCS), provided by the Laboratory for Atmospheric and Space Physics. Prior to the MESSENGER flybys Mercury’s exosphere was known to contain H and He, observed by Mariner 10, as well as Na, K, and Ca, observed from ground-based telescopes. When species are liberated from the surface with sufficient energy, those with strong resonance lines in the visible can be accelerated by solar radiation pressure in some circumstances to form an anti-sunward tail. During the three MESSENGER flybys, MASCS mapped Na, Ca, and Mg in the planet’s anti-sunward tail and also detected Ca+ in a narrow region approximately 1-2 Mercury radii above the anti-sunward surface. Some of the MASCS data are consistent with the picture of Mercury’s exosphere developed from ground-based observations of Na and Ca. On the other hand, unexpected spatial distributions of Mg, Ca and Ca+, suggest that the exosphere is more complex previously thought.
|March 4||Feng Tian||Planetary Upper Atmospheres under Strong XUV Radiation
Solar system terrestrial planets were exposed to strong (10~100 times present levels) soft X-ray and EUV radiation from the young Sun for several hundred million years after their formation. Planetary upper atmospheres expanded to several planetary radii under such XUV radiation and fast escape of major atmosphere gases occurred. The radial outflow, as a result of fast atmosphere escape, caused planetary upper atmospheres to deviate from the traditional hydrostatic equilibrium state, and a new regime, the hydrodynamic regime, is appropriate for the upper atmospheres of early solar system terrestrial planets. Because the hydrodynamic outflow effectively controlled the energy budget in planetary upper atmospheres, the total atmosphere escape could have been conserved regardless which particular atmosphere escape channel could have been dominant. Such a fundamental phenomena also applies to exoplanets such as hot Jupiters (already observed) and hot super Earths (future observations).
|March 11||Robert McCoy||Naval Space Science & Technology Initiatives
This will be a two-part talk focusing on both the basic and applied research programs at the Office of Naval Research (ONR) – and a couple at the Naval Research Laboratory (NRL). The ONR basic research portfolio is aimed at improved understanding of the ionosphere and thermosphere (I/T) and developing new sensors and models for specification and forecast of the I/T to provide advanced warning of communication and navigation outages – and forecast of satellite drag. Recently, NRL launched two ultraviolet remote sensing sensor platforms: the Special Sensor Ultraviolet Limb Imager (SSULI) on a polar orbiting DoD weather satellite; and the Remote Atmospheric and Ionospheric Detection System (RAIDS) on a Japanese HII-B rocket to the International Space Station. Early results of these UV remote sensing platforms will be presented along with a discussion of how these data sets fit into other ONR initiatives for assimilating Ionospheric models and future prospects for remote sensing of the I/T from geostationary orbit.
The ONR applied research program is focused on reducing the time and cost to deliver space hardware to orbit. ONR has sponsored a number of low cost, rapid space payload developments including: UHF communication from high earth orbit (HEO); maritime hyperspectral imaging of coastal shallow waters; data exfiltration from buoys and underwater vehicles; and ship tracking from space. Innovative new approaches include using cell phone and laptop technology and flying airborne payloads in pressurized boxes. In parallel, the DoD established the Operationally Responsive Space (ORS) Office in Albuquerque NM to develop architectures and designs for a whole new class of satellite buses and payloads to deliver capabilities to space faster and at lower cost than is conventionally available today. The ORS Office has goals to be able to launch a small satellite (100- 500 kg) in less than 6 days for a total development cost (bus + payload+ rocket) of less than $60M. Recent ORS spaceflights and future missions will be discussed.
|March 18||U. Konopka
Max-Planck-Institut f”ur extraterrestrische Physik,
Giessenbachstrasse, 85740 Garching, Germany
Complex Plasmas – From the Laboratory to Experiments on the
Dusty plasmas, or often called ”complex plasmas” have been studied for decades mainly related to plasma processing or astrophysical environments. 1994 an unfamiliar, ordered state of micro particles in a low temperature plasma environment, the so called ”plasma crystal” was discovered. As a result, the investigation of dusty plasmas was strongly intensified. The behavior of the charged particles within any kind of plasma environment, like low temperature rf, dc or atmospheric pressure plasma is now looked at. Especially the collective effects of larger particle systems with millions of fine particles, distributed isotropically in three dimensions gained much interest. Investigations include the study of wave phenomena, instabilities, particle flows, crystal structures as well as phase transitions, to name a few examples. All those phenomena can be studied, due to the nature of the complex plasmas, on the fundamental kinetic scale of individual particles. Compared to colloidal systems, which have a similar nature, complex plasmas cover also the hole dynamic range from over-damped to undamped system, what makes them unique. A significant knowledge in various research fields might be gained as a result of the interdisciplinarity of complex plasmas experiments. However, due to anisotropic forces acting on the negatively charged fine particles under earthbound conditions, it is difficult to establish an isotropic three dimensional system in the laboratory. In general, the fine particles are confined within the plasma volume due to strong electric fields that push the particles towards the plasma bulk out of the plasma sheath region. In balance with the ”strong” gravitational force, large particles tend to settle close to a lower sheath boundary, leading to vertically compressed particle clouds. For particles in the tens of micro meter range gravity can lead to a complete collapse of the particle cloud towards a mono-layer system, which of course is also of fundamental interest and thus studied extensively too. But, to study isotropic homogeneous fine particle plasmas, it is necessary either to use small sub-micro meter particles, which have the disadvantage that in general conditions their dynamic is over-damped, or to avoid the gravitational influence by performing experiments in microgravity environments, as are supported for example by drop tower experiments, parabolic flights or on the International Space Station (ISS). In the course of the talk, I will show examples of earth bound complex plasma experiments as well as some that were performed in parabolic flights or the Space Station experiments PKE-Nefedov or its successor PK-3Plus, that is operational since 2006.
|March 25||Scot Elkington (LASP)||Sources or Losses? The cause and effect of ultra low-frequency magnetospheric pulsations in the Van Allen radiation belts.
Geomagnetic activity is capable of dramatically affecting the relativistic electrons that comprise the outer zone of the Van Allen radiation belts, with approximately half of geomagnetic storms producing enhancements in the intensity of radiation in the belts, and the remainder either reducing relativistic electron fluxes or having no overall effect. Which of these outcomes will result from any given storm depends on a delicate balance between sources and losses of energy and particles in the system. In this seminar we look at recent work undertaken at LASP on the effects of continuous, low-frequency magnetospheric pulsations on the dynamics of the radiation belts. In particular, we examine the origin and effect of global ULF oscillations in the Pc-5 (mHz) frequency spectrum, and discuss their potential to act as either a source of transport and energy in the radiation belts, or to act as a loss process depleting the energetic electron fluxes in the radiation belts. We also examine the origin and evolution of a second class of ULF oscillations, Pc-1 (kHz) pulsations, which are related to Electromagnetic Ion Cyclotron (EMIC) activity in the magnetosphere and generally act to remove energy and particles from the radiation belts. Finally, we look at global radiation belt dynamics as it may be seen from the upcoming NASA Radiation Belt Storm Probes (RBSP) mission, under differing assumptions of ULF wave activity and source populations in the magnetosphere.
|April 1||Dr. Sascha Kempf (Max-Planck-Instute for Nuclear Physics, Heidelberg, Germany)||Liquid Water on Saturn’s Ice Moon Enceladus
In the light of the Cassini mission to Saturn, the moon Enceladus turned out to be one of the most intriguing bodies in the solar system. Data returned by several instruments on the 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 vapor 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 with the 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’ rocky core.
|April 8||Nicole Albers (LASP)||The F ring: One of Saturn’s most puzzling rings
Since the discovery of the F ring by Pioneer 11 it has been known as one of the most dynamic planetary rings in the Solar system. Located just outside Saturn’s main rings with its orbit right between those of the two shepherding moons Prometheus and Pandora, it is divided into the dense F ring core and more tenuous strands that seemingly wind themselves like a spiral. It’s location on the edge of the planet’s Roche zone suggests that processes of active aggregation and disaggregation could be present. While the Voyager missions provided initial support for the existence of a collision-dominated moonlet belt, latest Cassini observations have added a lot more detail to this picture. I will present an overview of the current understanding of the F ring and discuss recent results obtained using Cassini UVIS data.
|April 15||Xu Wang (LASP)||Laboratory studies of lunar dust transport.
There has been much evidence indicating dust levitation and transport on or near the lunar surface. Dust mobilization is likely to be caused by electrostatic forces acting on small lunar dust particles that are charged by UV radiation and solar wind plasma. Laboratory studies are needed for understanding physics of dust charging and dynamics on the lunar surface. Differential photoelectric charging and so-called “supercharging” on the surface near the lunar terminator region were created and studied in laboratory. Dust transport on surface in plasmas was investigated. A dust pile was observed to spread and form a diffusing dust ring on a negatively biased conducting surface in plasma. A dust patch was also found to spread on an electrically floating surface in plasma with an electron beam. Dust hopping was confirmed by noticing grains on protruding surfaces in both experiments. The 2-D electrostatic potential distributions were measured above the dusty surfaces and show electrostatic forces required for transport of the dust particles.
|April 22||Alysha Reinard (NOAA/SWPC)||Using helioseismology to improve space weather predictions
Solar flares and CMEs cause dramatic effects at the Earth, including damage to satellite electronics, loss of airline communications, and degradation, or even complete loss, of GPS. These effects become more disruptive as we become increasingly reliant on highly sophisticated technology. However, it is very difficult to predict when and where these events will occur or how large they will be. Helioseismology has recently emerged as a potentially powerful tool for understanding and predicting space weather events. In the last few years, a series of studies using ring diagram helioseismology has found evidence that signatures of subsurface twisting and emerging flux can be related to flaring activity. In particular, we have recently completed a study finding that these signatures are present 2-3 days prior to the occurrence of a flare. I will present these findings including the impacts on space weather forecasting capabilities.
|April 29||Richard Hodges (LASP)||SEMINAR CANCELLED
This seminar will be rescheduled in the Fall Semester.
The Lunar Atmosphere: Some Ado About Almost Nothing
Prior to the Apollo era the lunar atmosphere was thought to be a collision-less, ballistic conduit for thermal evaporation that balances the inflow of solar wind ions with their loss as neutrals. However, the first atmospheric species to be identified on the moon was radiogenic argon-40, and its identification was the indirect result of a search for an explanation of implanted parentless argon-40 in Apollo 11 soil samples. Subsequently, a neutral mass spectrometer at the Apollo 17 site confirmed the presence of atmospheric argon-40 along with helium of both solar and radiogenic origin.
These data, although meagre, have guided research into the processes that control the escape of gases from the moon and other bodies that have surface-bounded exospheres. Briefly, the dynamic characteristics of the atmosphere are dominated by ballistic transport, and perturbed by radiation pressure, charge exchange, photo-ionization, and escape to earth orbit. However, the most important atmospheric processes are related to the surface physics of regolith grains, that is, diffusion, adsorption, desorption, and elastic scattering, which in turn are affected by the influences of orography and heat flow on regolith temperature. With the upcoming launch of the Lunar Atmosphere and Dust Environment Explorer mission, new light should be shed on these processes as well as on the much-expected existence of other constituents.