Hosted at the AO, the colloquium series invites the most prominent figures in Space and Atmospheric Sciences, Radio Astronomy and Planetary Sciences to present and discuss the latest in their fields. All colloquia will be streamed live. Following the presentations there will be a section of questions and answers so that we can have an open discussion with the community of AO scientists, users and friends. Navigate the colloquia content and join us to participate in the discussion of some of the most thrilling science topics nowadays.
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- Ben Perera [Benetge.Perera@ucf.edu]
- Sean Marshall [firstname.lastname@example.org]
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11/19/2020 Future Prospects for Planetary Defense: Finding the Nearest Asteroids and Comets
Dr. Amy Mainzer
Lunar and Planetary Laboratory, University of Arizona
Thursday, Nov 19, 2020 1:00PM (AST)
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Date Name Affiliation Title Abstract 19 Nov 2020 DR. AMY MAINZER University of Arizona FUTURE PROSPECTS FOR PLANETARY DEFENSE: FINDING THE NEAREST ASTEROIDS AND COMETS ↳ View Bio, Abstract & Recordings
BioDR. AMY MAINZER
Affiliation: University of Arizona
About the Speaker.
Dr. Amy Mainzer is a professor of planetary science at the University of Arizona. Before that, she was a Senior Research Scientist at NASA’s Jet Propulsion Laboratory. At present, she studies asteroids and comets and designs visible and infrared instrumentation for planetary science and astrophysics. She has also studied giant planet atmospheres and low mass stars.
Prof. Mainzer is the principal investigator of NASA’s Near-Earth Object Wide-field Infrared Survey Explorer (NEOWISE) mission, an Earth-orbiting space telescope that is searching for Earth-approaching asteroids and comets. She is also the principal investigator of the proposed Near-Earth Object Surveyor mission, which would carry out a comprehensive survey of asteroids and comets using a dedicated space telescope. Prior to joining the Jet Propulsion Laboratory in 2003, she designed and built the fine guidance sensor for NASA’s Spitzer Space Telescope as an engineer at Lockheed Martin. The sensor she built was used daily by the observatory to initialize its pointing system throughout its mission from 2003 until its end in 2019.
Prof. Mainzer is a passionate advocate for science education, science literacy, and making science more equitable, diverse, and accessible to all. She has mentored several dozen students and serves as the science curriculum consultant, on-camera host, and executive producer of the PBS Kids series Ready Jet Go!, a TV show aimed at teaching physical science and Earth science to kids ages 3-8. The show produced 81 episodes and two movies. It is airing in dozens of countries, reaching hundreds of millions of viewers. Prof. Mainzer is the Chair of the American Astronomical Society’s Division for Planetary Sciences, the world’s largest professional society of planetary scientists. She serves as the chair of NASA’s Planetary Science Advisory Committee and is a member of the NASA Advisory Council Science Committee.
FUTURE PROSPECTS FOR PLANETARY DEFENSE: FINDING THE NEAREST ASTEROIDS AND COMETSs
19 Nov 2020
Much progress has been made over the last 20 years in discovering the largest near-Earth asteroids and constraining their orbits sufficiently well to know that more than 95% of the population >1 km has been discovered and poses no significant impact risk. Now, efforts have shifted to finding the majority of objects larger than ~100 m across, which have the potential to cause severe regional damage. The combination of multi-wavelength visible and infrared measurements of the population has shown that roughly 30% of near-Earth objects (NEOs) have very low albedos, and are therefore more difficult to detect at visible wavelengths, suggesting that visible and infrared surveys are complementary approaches for achieving high levels of survey completeness. One such proposed survey is the Near-Earth Object Surveyor, a mission that would search for NEOs using a 50-cm telescope operating at thermal infrared wavelengths. The mission would execute a fixed survey pattern, with the capability of interrupting the survey to perform detailed follow up as needed. As the known population of close-approaching asteroids increases, the need for advanced characterization tools and data processing capability to study objects of specific interest in detail will commensurately grow.
29 Sept 2020 DR. MICHAEL SULZER Arecibo Observatory / UCF THE PHYSICS OF INCOHERENT SCATTER WITH APPLICATION TO THE UNDERSTANDING OF THE PLASMA LINE SPECTRUM WITH NARROW PEAKS IN THE ELECTRON VELOCITY DISTRIBUTION FUNCTION ↳ View Bio, Abstract & Recordings
BioDR. MICHAEL SULZER
Affiliation: Arecibo Observatory / UCF
About the Speaker.
Mike Sulzer is a senior scientist at the Arecibo Observatory in the Space and Atmospheric Sciences Department, involved mostly in studies using the 430 MHz radar and the High Frequency Facility. He did his Phd. at The Pennsylvania State University in the Ionosphere Research laboratory of the Electrical Engineering Department. As part of that work he performed a D region modification experiment at the Arecibo Observatory using an early High Frequency Facility that used the 300 meter dish as its antenna in the early 1970s. He did his Post Doctoral work with Professor John Mathews at Case Western Reserve University; this consisted of D region studies at AO. Then he joined the staff at AO where he developed various radar and analysis techniques for probing the ionosphere using the 430 MHz radar, and did many experiments with the new High Frequency Facility located in Islote on the coast of Puerto Rico, using the radar as the diagnostic. Working with Jules Fejer, he showed that strong Langmuir turbulence plays a significant role in modification process.
He also performed experiments in the ionosphere designed to explore the behavior of light ions in the Arecibo ionosphere, working with Sixto Gonzalez. Later he performed theoretical calculations leading to spectra that showed that Coulomb collisions have a significant effect on the spectrum of incoherent scatter in the equatorial ionosphere over the Jicamarca Radio Observatory, explaining the long standing problem with the data analysis. After the Islote HF facility was destroyed in a hurricane, he had the idea of using a Cassegrain system at AO where the high power antennas are located near ground level just over the 300 meter dish, illuminating a secondary in the form of a hanging screen that then efficiently illuminates the dish. This idea was studied extensively with Professor James Breakall at PSU, leading to a facility that has been used for several years.
THE PHYSICS OF INCOHERENT SCATTER WITH APPLICATION TO THE UNDERSTANDING OF THE PLASMA LINE SPECTRUM WITH NARROW PEAKS IN THE ELECTRON VELOCITY DISTRIBUTION FUNCTION
29 Sep 2020
Incoherent scatter is a very useful diagnostic of the ionospheric plasma. A theoretical description of the scattered spectrum has been available for several decades, describing all the features, ion, plasma, and gyro lines, including the possibility of both Maxwellian and non-Maxwellian particle velocity distributions. Recently Djuth and Carlson (2018) identified features in the plasma line spectrum that they convincingly attributed to narrow peaks in the electron velocity distribution function caused by the solar ionizing EUV radiation. The observed features had unexpected narrow valleys in the spectrum as well as peaks, and all the features had unexpected frequency locations. However, the equations describing the incoherent scatter spectrum do predict the observed behavior of these features, but this alone is not completely satisfying.
Teaser interview w/ Dr. Mike Sulzer
Talk by Dr. Mike Sulzer (Virtual Session)
Postponed DR. TIMOTHY KENNEDY NASA Johnson Space Center in Houston, Texas RADAR OBSERVATIONS OF THE ORBITAL DEBRIS ENVIRONMENT IN LOW EARTH ORBIT ↳ View Bio, Abstract & Recordings
BioDR. TIMOTHY KENNEDY
Affiliation: NASA Johnson Space Center in Houston, Texas
About the Speaker.
Timothy Kennedy is the Radar Lead for the Orbital Debris Program Office at the NASA Johnson Space Center in Houston, Texas. He received a bachelor's (summa cum laude), master's, and Ph.D. in electrical engineering from the University of Houston in 2001, 2003, and 2006 respectively. He joined the NASA Johnson Space Center in 2005 working in the areas of computational electromagnetics modeling, antenna systems, radar, and sensor development for multiple human spaceflight programs. Prior to joining NASA he was with the Geophysics group at Schlumberger in Sugar Land, Texas working on inverse problems in layered media and software development. He has numerous publications and 20 US Patents in the areas of antenna systems, cooperative radar, computational electromagnetics modeling, radar and sensor development. His recent interests are in applications of Bayesian inference and machine learning to radar detection and object recognition. He has received multiple NASA Patent awards, the Federal Laboratory Consortium Notable Technology Award, Space Act Board award, Johnson Space Center Director's Commendations, and the NASA Exceptional Technology Achievement Medal.
RADAR OBSERVATIONS OF THE ORBITAL DEBRIS ENVIRONMENT IN LOW EARTH ORBIT
Currently there are more than 20,000 objects, approximately 10 cm and larger, tracked by the U.S. Space Surveillance Network (SSN). Due to the approximate power law relationship between the number of objects on orbit and the characteristic size of orbital debris, and the additional ground-based and in situ orbital debris measurement data available, the population of smaller orbital debris is even larger. Objects that have a characteristics size > 1mm represent significant risk to robotic spacecraft in LEO, and even smaller sizes pose significant risk to human missions. With population estimates exceeding 500,000 objects that are > 5 mm in low Earth orbit (LEO), it is currently not practical to track and maintain precision orbits on every object. To measure the distribution of smaller objects not tracked by the SSN, a statistical sampling approach to radar observations of the orbital debris environment is used. This talk describes the methods commonly applied for orbital debris radar observations, and the inferences that can made from these observations about the current environment.
28 Jan 2020 DR. ALAIN HERIQUE Institut de Planetologie et d’Astrophysique de Grenoble (IPAG) University Grenoble Alpes - FRANCE DIRECT OBSERVATIONS OF SMALL BODIES’ INTERIOR WITH RADAR ONBOARD PLANETARY PROBES. ↳ View Bio, Abstract & Recordings
BioDR. ALAIN HERIQUE
Affiliation: Institut de Planetologie et d’Astrophysique de Grenoble (IPAG) University Grenoble Alpes - FRANCE
About the Speaker.
Alain Herique was born in 1968. He received the Engineer degree in signal processing from the Ecole Nationale Supérieure d’Ingénieur Electricien de Grenoble, France, in 1991 and and a PhD from the Institut National Polytechnique de Grenoble in 1995. He is currently an associate professor at the Institut de Planétologie et d'Astrophysique de Grenoble, Université Grenoble Alpes, France. From 1992 to 1998 he worked at the CEPHAG in Grenoble on penetrating radar applied to planetary sciences. From 1998-1999 he was a system engineer with Alcatel Space Industries in Toulouse and studied new concepts of X-Band SAR instrument for Earth Observation for ESA. In 1999 he joined the LPG (now IPAG). He is studying small bodies’ internal structure fathomed by radars. His scientific research field include electromagnetic simulation of surface scattering and wave propagation in the subsurface, radar science (system design and simulation, calibration), dielectric properties and data inversion (signal processing, SAR processing, tomography) applied to planetary subsurface sounding and small bodies tomography. He is involved in many planetary space missions. He is PI of the CONSERT experiment on board Rosetta/ESA (previously Co-I and thereafter Deputy-PI). He is Co-I of Reason / Europa Clipper (NASA), and Wisdom /Exomars (ESA) and team member of MARSIS/MEx, RIME/JUICE. He has participated in many proposals of missions for NASA, ESA and JAXA. He is PI of the LFR radar on board the HERA/AIDA mission proposed to ESA, and of the GRIFIN radar on board Chimera proposed to Discovery.
DIRECT OBSERVATIONS OF SMALL BODIES’ INTERIOR WITH RADAR ONBOARD PLANETARY PROBES.
28 Jan 2020 (AST)
Despite some highly successful space missions to comets and asteroids, their internal structure remains largely unknown. Apart from CONSERT onboard Rosetta (ESA), which fathomed a limited part of the 67P/ Churyumov–Gerasimenko comet nucleus, our knowledge of the deep interior and shallow subsurface is based on theoretical modeling and on remote sensing observations of the surface. These questions are crucial to understand small bodies’ history from accretion in the early Solar System to the present. Radar onboard planetary probes is one of the most mature instruments capable to probe small bodies to characterize their internal structure from sub-meter to global scale. In this paper, we review the science case for direct observation of the deep internal structure and regolith of small bodies. We propose an instrument suite and its associated processing. We focus first on fathoming small bodies' regolith at higher resolution to understand the bodies' evolution processes, and then on probing the deep interior with a lower frequency bistatic radar to better model accretion/reaccretion processes. Bistatic radar for deep interior is illustrated with the CONSERT/Rosetta instrument and results. We then review the expected science return including secondary objectives, contributing to the determination of the gravitational field, the shape model, and the dynamical state. We then present programmatic perspectives in the frame of the Hera/ESA and Chimera/Discovery programs.
AO Colloquium Series: Dr. Alain Herique - Teaser Interview
January 28, 2020: Talk by Dr. Alain Herique @ AO Library
21 Jan 2020 DR. MICHAEL DENTON Space Science Institute, Boulder, Colorado and New Mexico Consortium, Los Alamos, New Mexico UNSOLVED PROBLEMS IN PLASMASPHERIC PHYSICS ↳ View Bio, Abstract & Recordings
BioDR. MICHAEL DENTON
Space Science Institute, Boulder, Colorado and New Mexico Consortium, Los Alamos, New Mexico
About the Speaker.
My research efforts are driven by a desire to understand the physical mechanisms at work in the solarterrestrial environment. These mechanisms include direct particle-particle collisions (e.g. in the upper atmosphere) and waveparticle interactions in tenuous plasmas of the solar system (e.g. the solar wind). Recent research has focused on (i) the Earth's radiation belts, (ii) refilling processes in the ionosphere/plasmasphere, and (iii) empirical forecasting of particle populations in the inner magnetosphere. I have active research collaborations with scientists in various countries around the world.
Current Position(s): Research Scientist at Space Science Institute (since 2012) and New Mexico Consortium (since 2015).
- Previous Position(s): Senior Lecturer, Department of Physics, Lancaster University, UK, 2011- 2015.
- Lecturer, Department of Physics/Comms., Lancaster University, UK, 2006-2011.
- Research Fellow,Univ. Southampton, UK, 2006-2006.
- Research Associate, LANL, USA, 2003-2005.
- Research Assistant, Dept. of Physics, Uni. Wales, UK, 2000-2003.
- Ph.D. Thermal balance of the topside ionosphere, App. Math., Sheffield, UK, 2000.
- B.Sc. Physics, Dept. of Physics, University of Sheffield, UK, 1997.
UNSOLVED PROBLEMS IN PLASMASPHERIC PHYSICS
21 Jan 2020 2:00PM (AST)
The plasmasphere is a region of cold (~1 eV) plasma that forms from the up flow of ionospheric material on closed magnetic field lines. In this colloquium, we present a brief history of plasmaspheric research, summarize our current understanding of plasmapheric dynamics, and discuss ground-based and space-based observations of the plasmasphere. We also outline the limits of our current knowledge of the plasmasphere and list outstanding science questions where our understanding is incomplete. Finally, we discuss potential new facilities/missions that could make progress on better understanding this important and dynamic region of the coupled Sun-Earth system.
Teaser Interview w/ Dr. Michael Denton: He talks about his upcoming colloquium at AO while telling us a little bit about himself! 21-Jan-2020: Talk by Dr. Michael Denton: @ AO Library
Date Name Affiliation Title Abstract 15 Oct 2019 ASSOC. PROF. SCOTT ENGLAND Dep. of Aerospace & Ocean Engineering, Virginia Tech EXPLORING THE BOUNDARY BETWEEN EARTH & SPACE WITH ICON ↳ View Bio, Abstract & Recordings
BioASSOC. PROF. SCOTT ENGLAND
Dep. of Aerospace & Ocean Engineering, Virginia Tech
About the Speaker.
Scott England is an Associate Professor in the Aerospace and Ocean Engineering Department at Virginia Tech. He did his PhD at the University of Leicester, UK, studying coupling of energy and momentum between different regions of the atmosphere via atmospheric waves. He spent 12 years at the Space Sciences Laboratory at the University of California, Berkeley, where his studies focused on the interaction between atmospheric waves and charged particles in the near-Earth space environment. He came to Virginia Tech in 2016, and currently focuses on using remote sensing instruments to study the upper atmosphere and near-earth space environment. He is the Project Scientist for the upcoming NASA ICON spacecraft, a Co-Investigator on the upcoming NASA GOLD spaceflight mission, and a Participating Scientist on the NASA MAVEN mission to Mars.
EXPLORING THE BOUNDARY BETWEEN EARTH & SPACE WITH ICON
2 Oct 2019 2:00PM (AST)
The near-Earth space environment is far from empty. Occupying the region where astronauts and low-earth-orbiting spacecraft fly is a the last, most tenuous portion of our atmosphere. Sunlight breaks apart the molecules of gas at these altitudes, creating exotic and corrosive species such as atomic oxygen, as well as charged ions and electrons. Spacecraft and astronauts flying in this region experience impacts from all of these in the form of atmospheric drag, which modifies the orbits of low-flying spacecraft, surface corrosion and electrostatic charging, and impacts on radio communications. Understanding this region has proved challenging as it is highly variable, difficult to access, and feels the influence of both the sun and processes occurring much lower in our atmosphere. With the serendipitous development of multiple new spaceflight missions designed to study this region, a rare opportunity to solve significant outstanding problems in space physics has presented itself. One of these is the upcoming ICON mission will observe the thermosphere using optical and in-situ instruments from low-Earth-orbit. Combining these observations effectively with ground-based observations and numerical models to address questions of ion-neutral coupling and upper-atmosphere dynamics will require collaboration between many research groups around the world. This seminar will focus on the science and observations of the ICON mission and the opportunities they present.
AO Colloquium Series: Associate Professor Scott England - Teaser Interview AO Colloquium Series: Associate Professor Scott England - Talk
2 Oct 2019 PROF. AVINASH DESHPANDE Raman Research Institute, Bangalore, India FASCINATING LIFE-STORIES OF COSMIC LIGHT-HOUSES ↳ View Bio, Abstract & Recordings
BioPROF. AVINASH DESHPANDE
Affiliation: Raman Research Institute, Bangalore, India
About the Speaker.
Works at Raman Research Institute, Bangalore, in their Astronomy & Astrophysics group, since 1980.(EE BTech 1980 IIT Kanpur; EE PhD 1988 IIT Bombay). Primarily engaged in radio astronomy activities. Signal and image processing, instrumentation, and understanding noise & uncertainties are also his interests. He has been trying to learn about these and other issues in the context of pulsars, interstellar medium and radio interferometry.
FASCINATING LIFE-STORIES OF COSMIC LIGHT-HOUSES
2 Oct 2019 2:00PM (AST)
VHF radar echoes are of origin of refractive index fluctuations and its gradient. These fluctuations are of turbulence. Atmospheric turbulence studies are mostly made by refractive index fluctuation induced radar echoes. These echoes are expected to be an intermittent in space and time since turbulence are highly intermittent in space and time. VHF radar echoes are characterized by different techniques for basic understanding on it and then those echoes are used to study atmospheric turbulence. A new method is being developed for turbulence studies since radar estimated spectral width method has inherent problem. VHF radar echoes from the low latitude mesosphere have been extensively studied using the Jicamarca radar located in Peru and more recently using the MST radar located at Gadanki. This study focuses on studying the low latitude mesospheric echoes extending up to the mesospause (which is ~100 km), which include echoes generated by neutral turbulence below 80 km an! d by plas ma instability above 87 km, turbulence characteristics, and the governing dynamics. Studies have been done using observations made by ground based radars (MST, MF, meteor radars), lidar and ionosonde; rocket borne Langmuir probe; and satellite. Observations have revealed that radar echoes during daytime are observed from two height regions: 60-80 km and 87-102 km. The echoes observed in the height region of 65-80 km are observed in all beam direction while the echoes from 87-102 km are observed in the direction that satisfies perpendicularity to earth�s magnetic field. The echoes from 65-80 km are attributed to the electron density fluctuations generated by neutral turbulence in the mesosphere and are referred to as low latitude mesospheric echoes while the echoes from the 87-102 km are attributed to field aligned electron density irregularities in the E region generated by plasma instability and are referred to as low latitude E region echoes. Both are found to be govern! ed direct ly or indirectly by the neutral dynamics. These findings indicate that the refractive index fluctuations responsible for VHF radar echoes from the low latitude mesosphere are related to neutral turbulence and the turbulence is closely linked with gravity wave activities. These results are discussed inthe light of current understanding on the governing processes and dynamical forcing generating the low latitude mesospheric echoes. Echoes from MLT region are also depends on electron density of that region. Retrieval of electron density has been attempted in D and E region using Incoherent Scattering Radar (ISR) technique and this same technique has also been applied to upper atmosphere/ionosphere.
AO Colloquium Series: Prof. Avinash Deshpande - Teaser Interview
AO Colloquium Series: Prof. Avinash Deshpande - Talk at AO Library - Oct 2, 2019 (Duration: 1.5 hrs)