S. Protopapa
A5073215608- Astro and Planetary Science
- Planetary Science and Exploration
- Isotope Analysis in Ecology
- Stellar, planetary, and galactic studies
- Astrophysics and Star Formation Studies
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Atmospheric Ozone and Climate
- Spacecraft and Cryogenic Technologies
- Geological and Geochemical Analysis
- Astronomy and Astrophysical Research
- Nuclear Physics and Applications
- Gamma-ray bursts and supernovae
- High-pressure geophysics and materials
- Solar and Space Plasma Dynamics
- Nuclear physics research studies
- Geomagnetism and Paleomagnetism Studies
- Astronomical and nuclear sciences
- Astronomical Observations and Instrumentation
- History and Developments in Astronomy
- Ionosphere and magnetosphere dynamics
- Methane Hydrates and Related Phenomena
- Atmospheric and Environmental Gas Dynamics
- Atomic and Molecular Physics
- Space exploration and regulation
Southwest Research Institute
2016-2024
Campbell Collaboration
2022
Jet Propulsion Laboratory
2021
Scotch Whisky Research Institute
2021
University of Maryland, College Park
2011-2018
Stanford University
2018
Université de Reims Champagne-Ardenne
2016
United States Geological Survey
2016
Max Planck Institute for Solar System Research
2008-2012
Max Planck Society
2009-2012
In situ observations show that comet Hartley 2 is an unusually hyperactive comet.
The New Horizons spacecraft mapped colors and infrared spectra across the encounter hemispheres of Pluto Charon. volatile ices CH$_4$, CO, N$_2$, that dominate Pluto's surface, have complicated spatial distributions resulting from sublimation, condensation, glacial flow acting over seasonal geological timescales. H$_2$O ice "bedrock" is also mapped, with isolated outcrops occurring in a variety settings. surface exhibits complex regional color diversity associated its distinct provinces....
Jupiter's moon Europa has a subsurface ocean beneath an icy crust. Conditions within the are unknown, and it is unclear whether connected to surface. We observed with James Webb Space Telescope (JWST) search for active release of material by probing its surface atmosphere. A plumes yielded no detection water, carbon monoxide, methanol, ethane, or methane fluorescence emissions. Four spectral features dioxide (CO2) ice were detected; their shapes distribution across Europa's indicate that CO2...
The dwarf planets Sedna, Gonggong, and Quaoar are interesting in being somewhat smaller than the methane-rich bodies of Kuiper Belt (Pluto, Eris, Makemake), yet large enough to be spherical have possibly undergone interior melting differentiation. They also reside on very different orbits, making them an ideal suite for untangling effects size orbit present day surface composition. We observed with NIRSpec instrument James Webb Space Telescope (JWST). All three were low-resolution prism mode...
<i>Context. <i/>The goal of the <i>Herschel<i/> open time programme "<i>TNOs are Cool!<i/>" is to derive physical and thermal properties for a large sample Centaurs, trans-Neptunian objects (TNOs), including resonant, classical, detached scattered disk objects.<i>Aims. <i/>Based on observations two targets we tried (i) optimise SPIRE observing technique faint (close background confusion noise), slowly moving targets; (ii) test different model techniques; (iii) determine radiometric diameter...
We describe recent results on the CO/CO2/H2O composition of comets together with a survey older literature (primarily for CO/H2O) and compare these models protoplanetary disk. Even currently small sample, there is wide dispersion in abundance ratios little if any systematic difference between Jupiter-family (JFCs) long-period Halley-type (LPCs HTCs). argue that cometary observations require reactions grain surfaces to convert CO CO2 also formation all types largely, but not entirely,...
Impact craters on Pluto and Charon Collisions between Solar System bodies produce impact large objects at a rate that depends the population of impacting small bodies. Singer et al. examined its moon Charon. Some regions have had their erased by recent geological processes, but others appear to record 4 billion years impacts. Because are located in Kuiper belt, distribution crater sizes reflects size belt (KBOs). The authors found fewer KBOs than predicted models collision equilibrium,...
The New Horizons mission has provided resolved measurements of Pluto's moons Styx, Nix, Kerberos, and Hydra. All four are small, with equivalent spherical diameters $\approx$40 km for Nix Hydra ~10 Styx Kerberos. They also highly elongated, maximum to minimum axis ratios $\approx$2. have high albedos ( $\approx$50-90 %) suggestive a water-ice surface composition. Crater densities on imply ages $\gtrsim$ 4 Ga. small rotate much faster than synchronous, rotational poles clustered nearly...
Asteroids with diameters less than about 5 km have complex histories because they are small enough for radiative torques, YORP, to be a notable factor in their evolution. (152830) Dinkinesh is asteroid orbiting the Sun near inner edge of Main Asteroid Belt heliocentric semimajor axis 2.19 AU; its S type spectrum typical bodies this part Belt. Here we report observations by Lucy spacecraft as it passed within 431 Dinkinesh. revealed Dinkinesh, which has an effective diameter only $\sim$720 m,...
We present an update of the visible and near-infrared colour database Minor Bodies in Outer Solar System (MBOSSes), which now includes over 2000 measurement epochs 555 objects, extracted from 100 articles. The list is fairly complete as December 2011. large enough to enable any dataset with a dispersion be safely identified rejected analysis. selection method used quite insensitive individual outliers. Most datasets were observed during early days MBOSS photometry. measurements are combined...
Abstract We observed the newly discovered hyperbolic minor planet 1I/‘Oumuamua (2017 U1) on 2017 October 30 with Lowell Observatory’s 4.3 m Discovery Channel Telescope. From these observations, we derived a partial lightcurve peak-to-trough amplitude of at least 1.2 mag. This segment rules out rotation periods less than 3 hr and suggests that period is 5 hr. On assumption variability due to changing cross-section, axial ratio 3:1. saw no evidence for coma or tail in either individual images...
We report the detection of ammonia (NH3) on Pluto's surface in spectral images obtained with New Horizons spacecraft that show absorption bands at 1.65 and 2.2 μm. The signature is spatially coincident a region past extensional tectonic activity (Virgil Fossae) where presence H2O ice prominent. Ammonia liquid water profoundly depresses freezing point mixture. Ammoniated ices are believed to be geologically short lived when irradiated ultraviolet photons or charged particles. Thus, NH3...
We present Herschel PACS photometry of 18 Plutinos and determine sizes albedos for these objects using thermal modeling. analyze our results correlations, draw conclusions on the Plutino size distribution, compare to earlier results. Flux densities are derived from mini scan-maps specialized data reduction methods. In order improve quality results, we combine with existing Spitzer MIPS where possible, refine absolute magnitudes targets. The physical characterization sample is done a model....