Date: Monday 05-Feb-2018
Speaker: Lori Feaga (UMD)
Title: Characteristics of the surface of comet 67P/Churyumov-Gerasimenko
During Rosetta's two year study of 67P/Churyumov-Gerasimenko (C-G), the surface of the comet was observed with a suite of instruments revealing its surface properties, composition, widely varying morphology, and transient features. I will present a summary of what we have learned about the surface, using various methods across all wavelengths, and how C-G compares to other cometary nuclei that have been visited by spacecraft.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 12-Feb-2018
Speaker: Christine Hartzell (UMD)
Title: Granular Mechanics on Asteroids: The influence of non-gravitational forces
While asteroids vary significantly in size, morphology and chemical composition, there is a consistent need to understand the behavior of granular materials in order to improve understanding of the evolution of these bodies. The behavior and interactions of grains drives the interior structure of small, “rubble pile” asteroids, and may strongly influence the surface morphology across the range of asteroid sizes. Due to the weak gravity and lack of an atmosphere on these bodies, non-gravitational forces can dominate the interactions of grains. This talk will discuss the physics and dynamics of electrostatic dust lofting and levitation on asteroids, as well as plans to look for signatures of these phenomena at Bennu. On-going experimental work to understand triboelectric charging of regolith as well as computational studies to quantify the significance of magnetic forces in regolith on metallic asteroids will also be discussed.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 19-Feb-2018
Speaker: No PALS
Title: No PALS
Abstract No PALS
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 26-Feb-2018
Speaker: TBD
Title: TBD
Abstract TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 05-Mar-2018
Speaker: postponed to May 14 - Nancy Chabot (JHU-APL)
Title: postponed to May 14 - Mercury's Water Ice Polar Deposits
Talk postponed
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 12-Mar-2018
Speaker: No PALS
Title: No PALS
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 19-Mar-2018
Speaker: No PALS [Spring Break]
Title: No PALS [Spring Break]
Abstract TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 26-Mar-2018
Speaker: Nilda Oklay/Jean-Baptiste Vincent (DLR)
Title: Large sub-surface volatile reservoirs of comet 67P / Evolution of cometary surfaces
Abstract (Oklay): Surface regions enriched in water ice are key to the sub-surface volatile reservoirs of comet 67P. Long-term high spatial resolution multispectral OSIRIS images of comet 67P allowed the detection and investigation of several water ice rich activity sources. Here, I will present detection of repeating activity from a large round basin (~700 m in diameter), which may indicate a large volatile reservoir on the big lobe of the comet. In this basin, I visually detected more than 30 transient activity events in which, several of those were repeating from the same source, which helps us to understand the sub-surface structure of the comet. Characterization of these events and associated source regions will be useful to put constrains to the cometary activity mechanisms that are in discussion. This has implications to the formation and evolution of comets. I will present the preliminary results of the characterization these events combining information from morphologic, spectroscopic and statistical analyses.
Abstract (Vincent): Cometary surfaces evolve a shorter time scale than other small bodies in the Solar System. Because changes are principally driven by the sublimation of volatiles in the subsurface, it is expected that most of the evolution takes place when the comet orbit brings the nucleus within the inner Solar System. Yet, this is not the whole picture.
Indeed, very few topographic changes have been observed on the cometary nuclei visited by spacecraft so far. For instance, only a handful of modifications were detected during the 2 years Rosetta orbited comet 67P. Thus, it is now postulated that the large scale topographic features are not a result of the erosion, bur rather formed very early in the history of the comet.
Yet comets still evolve, but perhaps at a different pace than initially thought. Recent development in mapping and image processing allow us to track changes on the surface at scales <10m. We found thousand of small surface modifications, from the opening of small pits, to jumping boulders, and expanding fracture networks. I will present some of these changes and discuss how they open a new window into cometary physics, at scales not investigated before.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Thursday 29-Mar-2018
Speaker: Sam Birch (Cornell)
Title: Investigating the Morphology and Topography of Titan's Polar Lacustrine Features
Saturn's largest moon Titan is the second known solar system body on which standing bodies of liquid are maintained, the first being Earth. Under Titan's current climatic conditions, stable surface liquids are restricted to the polar regions. There, liquids pond within two distinct types of depressions: open basins, and sharp-edged depressions (SEDs). However, modern liquid bodies are largely restricted to North polar latitudes with a comparatively small volume of liquid in the southern hemisphere. This dichotomy has previously been attributed to Saturn's current orbital configuration, but if correct, the configuration is transient and southern depositional basins equivalent in volume to the northern seas are required. In the South polar region, we have identified four dry broad depressions, equivalent in area to the northern seas. I will detail the morphologic and topographic data that suggest that these features represent paleoseas that were filled during an earlier epoch, more favorable to the accumulation of southern liquids. I will also detail work we have done to understand the formation of Titan’s SEDs, karst-like features traditionally thought to form via dissolution of a soluble substrate. Specifically, I will detail the topographic and image data that together have revealed the presence of hundred-meter high raised rims around the perimeters of most these features. The presence of these rims defy explanation and add serious complications that cannot be explained by dissolution erosion alone.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 02-Apr-2018
Speaker: Carrie Holt (UMD)
Title: Spatial Variations of Comet 103P/Hartley 2's Volatiles: Three Weeks of Deep Impact Data
In 2010, the Deep Impact spacecraft flew by comet 103P/Hartley 2 as part of its extended mission. Hartley 2 is a comet of significance because of its hi gh water production rates, making the mission the only flyby of a hyperactive comet. The Deep Impact spacecraft scans across the comet every 15 minutes to every hour so that the infrared spectrometer on board can create spectral maps of the coma at different wavelengths (1.05-4.85 microns). This techniq ue allows us to study the asymmetries in the coma, particularly of water and carbon dioxide. I will discuss the uniqueness of the flyby mission and the asymmetries and temporal variations evaluated throughout 23 days of observation through closest approach.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 09-Apr-2018
Speaker: Anne Raugh (UMD)
Title: An Introduction to the PDS4 Standards: Concepts and Consequences
The Planetary Data System (PDS) is a distributed archive of planetary data primarily from NASA's planetary exploration missions. NASA established the PDS in the late 1980s to preserve then-endangered data from its first planetary missions. The mandate to PDS was not merely to preserve the bytes, but to maintain the data and ensure its usability to future generations. After 25 years of operation under its original standards and system design, PDS re-engineered its entire software infrastructure and archive standards using contemporary, open archive standards and information architecture methodologies, producing the standards and support structure now known as "PDS4".
I will present a brief history of the PDS for the uninitiated, then present the core concepts and the new PDS4 Information Model and related standards in order to provide new users - which is effectively all users, now - with context and background for understanding what is in a PDS4 product label and archive collection, and why.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Thursday 12-Apr-2018
Speaker: CANCELLED - Driss Takir (SETI)
Title: CANCELLED
CANCELLED
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 16-Apr-2018
Speaker: Kathy Mandt (JHU-APL)
Title: The Search for Volatiles on the Moon with the Lunar Reconnaissance Orbiter (LRO)
In order to enable future human exploration of the Moon, astronauts will require access to in situ resources that are able to provide them with water and fuel. These resources are found in the highest abundances in the polar regions, where there are Permanently Shadowed Regions (PSRs) – several thousand square kilometers of low lying areas are never exposed to sunlight. Observations made by the neutron detector on Lunar Prospector found increased levels of hydrogen at the poles but was not able to differentiate between hydrogen implanted by the solar wind, hydroxyl bound to minerals and pure water. Later, the Chandrayaan-1 mission found sprectrographic evidence for water, which appeared to be more abundant closer to the poles. Two NASA missions were conceived to prepare for future human spaceflight to the Moon: The Lunar Reconnaissance Orbiter (LRO) and The Lunar Crater Observation and Sensing Satellite (LCROSS) mission. Of particular interest for these missions is the abundance and composition of volatiles in PSRs. LRO carries seven instruments, each of which contributes unique information about volatiles on the Moon. The LRO and LCROSS spacecraft collected data from the impact of their launch vehicle’s spent Centaur upper stage into the Cabeus Crater PSR. The LRO Lyman Alpha Mapping Project (LAMP) detected H2, CO, Hg, Mg and Ca in the plume resulting from the impact, while LCROSS observed a large amount of water and a few percent H2S, NH3, SO2, C2H4, CO2, CH3OH, CH4 and OH. What is most striking is the similarity between the composition of the plume volatiles and the composition of comets, indicating that comets could have made an important contribution to the volatiles sequestered in the Lunar poles. LRO continues to make observations of the Moon, mapping water frost and ice at various depths. We will discuss this ongoing work and the implications for the origin of volatiles on the Moon and for the future of human exploration.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 23-Apr-2018
Speaker: Sara Faggi (GSFC)
Title: The Volatile Composition of comets: The newly-discovered C/2017 E4 (Lovejoy) before its dissolution as revealed by iSHELL at NASA/IRTF
Comets are considered the most pristine bodies of the solar system and their investigation through cosmogonic parameters provides important information on native conditions in the solar nebula. Our knowledge about infant stages of our planetary system is still fragmentary and cometary nuclei retain the least processed material from that era. Investigation of comets composition, based on cosmogonic indicators, is essential for testing models of Solar System formation and evolution, for assessing cometary delivery of organic compounds to the early Earth, and for addressing the origin of water on Earth.
In April 2017, we acquired comprehensive high-resolution spectra of newly-discovered comet C/2017 E4 (Lovejoy) as it approached perihelion, and before its disintegration. We detected many cometary emission lines across 4 customized instrument settings (L, L3, Lp1 and M1) in the (1.1 – 5.2) micron range, using iSHELL - the new near-IR high resolution immersion echelle spectrograph on NASA/IRTF (Mauna Kea, Hawaii).
Around 3 microns, in L1, we detected fluorescence emission from HCN, C2H2, water, prompt emission from OH, and many other features. Methane, ethane and methanol were detected both in L3 and Lp1 settings. These species are relevant to astrobiology, owing to questions regarding the origin of pre-biotic organics and water on terrestrial planets. In M1, near 5 micron, we detected multiple ro-vibrational lines of H2O, CO and the (X-X) system of CN; the latter data constitute a complete survey of CN at these wavelengths.
The many water emission lines detected in L1 and M1 provided an opportunity to retrieve independent measures of rotational temperature for ortho- and para-H2O, thereby reducing systematic uncertainty in the derived ortho-para ratio and nuclear spin temperature. Deuterated species were also sought and results will be presented.
The bright Oort cloud comet E4 Lovejoy combined with the new capabilities of iSHELL provided unique results. The individual iSHELL settings cover very wide spectral range with very high accuracy, eliminating many sources of systematic errors when retrieving molecular abundances; future comparisons amongst comets will clarify the nature and meaning of cosmogonic indicators based on composition.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 30-Apr-2018
Speaker: No PALS
Title: No PALS
Abstract None
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 07-May-2018
Speaker: Adam McKay (GSFC)
Title: The Peculiar Volatile Composition of CO-Dominated Comet C/2016 R2 (PanSTARRS)
Comets contain primitive volatile material that is reflective of the physics and chemistry operating in the protosolar disk during planet formation. The volatile content of comets is typically dominated by H2O, followed by CO2 and CO, and then trace amounts of species such as CH4, NH3, CH3OH, C2H6, H2CO, and HCN. However, this is not always applicable, especially for CO, for which abundances compared to H2O vary by several orders of magnitude. N2, while difficult to detect remotely, has been found to be heavily depleted in comets, with NH3 being the dominant volatile reservoir for nitrogen. In December 2017 we obtained optical spectra of comet C/2016 R2 (PanSTARRS) that were extremely atypical for comets observed at optical wavelengths. Usually dominated by neutral species such as CN and C2, the optical spectrum of C/2016 R2 was devoid of these features and was instead dominated by ionic emissions from CO+ and N2+, with the N2+ detection being the most secure detection of N2+ in a comet obtained in the age of digital detectors (Cochran and McKay 2018). Additional sub-mm observations showed strong CO emission (Wierzchos and Womack 2017, 2018, de Val Borro et al. 2018, N. Biver in prep.), confirming the hypervolatile-rich nature of this comet suggested by the optical spectra. We present additional observations of C/2016 R2 obtained with the IRAC instrument on the Spitzer Space Telescope, iSHELL on the NASA IRTF, ARCES at Apache Point Observatory, the Tull Coude Spectrograph at McDonald Observatory, and Arizona Radio Observatory 10-m Submillimeter Telescope during January-February 2018 aimed at characterizing the volatile composition of this unusual comet. We will discuss our measured abundances of key species and discuss implications for the chemistry in the early Solar System.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 14-May-2018
Speaker: Nancy Chabot (JHU-APL)
Title: Mercury's Water Ice Polar Deposits
Even though Mercury is the planet closest to the Sun, there are places at its poles that never receive sunlight and are very cold – cold enough to hold water ice. In this presentation, I’ll show the multiple lines of evidence that regions near Mercury’s poles hold water ice – from the first discovery by Earth-based radar observations to multiple data sets from NASA’s MESSENGER spacecraft, the first spacecraft ever to orbit the planet Mercury. These combined results suggest that Mercury’s polar ice deposits are substantial, perhaps comparable to the amount of water in Lake Ontario. Where did the ice come from and how did it get there? I’ll discuss these questions and others, as well as future work that can lead us to new insights about water ice on Mercury and in the inner Solar System in general.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 13-Aug-2018
Speaker: Adeline Giquel-Brodtke (JPL)
Title: Modelling of the activity (gas and dust) of comet 67P/Churyumov- Gerasimenko during the summer of 2015 with Rosetta
The ESA Rosetta spacecraft reached comet 67P/Churyumov-Gerasimenko (67P) in August 2014, and over the course of the 2.5 year mission, many outbursts were seen. Close to perihelion in August 2015, a display of 34 outbursts on 67P (Vincent et al. 2016) were observed with the Optical, Spectroscopic, and Infrared Remote Imaging System (OSIRIS) and the Navigation Camera (NAVCAM). Many of these were also detected by the Microwave Instrument for the Rosetta Orbiter (MIRO). I hope to better understand the physics creating outbursts on the surface of comets and derive the dust/gas ratio by using the OSIRIS/NAVCAM images (more sensitive to the dust) and MIRO spectra (more sensitive to the gas). I use a Collisionless Gas Simulation to model the gas flow from the nucleus and in the coma. I have added dust-grains to our collisionless gas model, with dust trajectories controlled by gas drag, gravity and radiative pressure. I assume that the dust particles start with zero velocity at the nucleus surface, and are initially accelerated by gas flow perpendicular to the surface. A distribution of dust sizes is included in the model. Mie theory is used to calculate the optical properties of the dust, and I’m in the process of simulating sunlight scattered by the dust particles. I will present the physics of the models being used and hope to be able to compare simulated visible-wavelength images with OSIRIS and NAVCAM data.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 10-Sep-2018
Speaker: No PALS
Title: No PALS
TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 17-Sep-2018
Speaker: No PALS
Title: No PALS
TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 24-Sep-2018
Speaker: Elizabeth Warner (UMD)
Title: UMD Observatory Assets and Research
The University of Maryland Observatory has lots of equipment acquired through grant purchases, tech fees proposals, crowdfunding, and donations. There's even some equipment that's been abandoned and some 'lost' and found. Learn about what we have currently and the active research being done with some of this gear. I'll also go over some of the abandoned and found instruments and what we hope to be able to do.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 1-Oct-2018
Speaker: Jennifer Whitten (Smithsonian)
Title: Echoes of the Marian Climate: Radar Sounding of Ice Sheets
The south polar region of Mars is one of the largest reservoirs of water ice on the planet. Both the Amazonian south polar layered deposits (SPLD) and the Hesperian Dorsa Argentea Formation (DAF) are proposed to contain substantial amounts of water ice. The age of these two units, the SPLD and DAF, suggest that a long-lived climate record may be preserved in these icy deposits in the south polar region of Mars. Using radar sounder data from the SHARAD and MARSIS instruments Dr. Whitten has investigated the internal structure and composition of the SPLD and the DAF to further constrain the climate record in this region of Mars.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 8-Oct-2018
Speaker: No PALS
Title: No PALS - PDS review
TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 15-Oct-2018
Speaker: DPS practice talks
Title: DPS practice talks
Carrie Holt "Continuous Monitoring of Spatial Variations in 103P/Hartley 2’s Volatiles from Deep Impact"
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 22-Oct-2018
Speaker: No PALS
Title: No PALS - DPS
TBD
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 29-Oct-2018
Speaker: Tony Farnham (UMD)
Title: The close approach of Comet 46P/Wirtanen
Comet 46P/Wirtanen is an inherently interesting comet that is also likely to be a spacecraft target in the future. It is approaching perihelion, shortly after which it will make a historically close approach to the Earth, and this apparition offers a unique opportunity to characterize the comet's behavior in a manner that is rarely possible. I will discuss the close approach and its implications, as well as the observing campaign that we are running to maximize the scientific return from this apparition.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
Date: Monday 5-Nov-2018
Speaker: Anais Bardyn (DTM)
Title: The dust of comet 67P/Churyumov-Gerasimenko
After a 10-year journey, the European spacecraft Rosetta arrived at comet 67P/Churyumov-Gerasimenko (67P) on August 6, 2014. In order to conduct intensive research for 26 months, a total of 21 instruments were on board the Rosetta orbiter and the Philae lander. The mass spectrometer named COSIMA (Cometary Secondary Ion Mass Analyzer) was one of the orbiter instrument and was designed to collect cometary dust particles ejected from 67P nucleus, imaged them and analyzed in situ their composition. I will present the Rosetta space mission, as well as results from the COSIMA instrument regarding the organic content of the cometary dust particles.
For further information contact PALS coordinator Dr. Matthew Knight at knight@astro.umd.edu or (301)-405-2629.
