Showing papers by "Carly Howett published in 2019"
Planetary Science Institute1, Goddard Space Flight Center2, California Institute of Technology3, United States Geological Survey4, Scripps Institution of Oceanography5, Wheaton College (Massachusetts)6, Woods Hole Oceanographic Institution7, Cornell University8, Ames Research Center9, Southwest Research Institute10, University of Arizona11, University of Western Ontario12, Johns Hopkins University Applied Physics Laboratory13, Georgia Institute of Technology14, Massachusetts Institute of Technology15
TL;DR: To map out a coherent Ocean Worlds Program, significant input is required from studies here on Earth; rigorous Research and Analysis studies are called for to enable some future ocean worlds missions to be thoughtfully planned and undertaken.
Abstract: In this article, we summarize the work of the NASA Outer Planets Assessment Group (OPAG) Roadmaps to Ocean Worlds (ROW) group. The aim of this group is to assemble the scientific framework that will guide the exploration of ocean worlds, and to identify and prioritize science objectives for ocean worlds over the next several decades. The overarching goal of an Ocean Worlds exploration program as defined by ROW is to “identify ocean worlds, characterize their oceans, evaluate their habitability, search for life, and ultimately understand any life we find.” The ROW team supports the creation of an exploration program that studies the full spectrum of ocean worlds, that is, not just the exploration of known ocean worlds such as Europa but candidate ocean worlds such as Triton as well. The ROW team finds that the confirmed ocean worlds Enceladus, Titan, and Europa are the highest priority bodies to target in the near term to address ROW goals. Triton is the highest priority candidate ocean world to target in the near term. A major finding of this study is that, to map out a coherent Ocean Worlds Program, significant input is required from studies here on Earth; rigorous Research and Analysis studies are called for to enable some future ocean worlds missions to be thoughtfully planned and undertaken. A second finding is that progress needs to be made in the area of collaborations between Earth ocean scientists and extraterrestrial ocean scientists.
215 citations
TL;DR: Stern et al. as mentioned in this paper presented the initial results from the New Horizons flyby of MU_(69) on 1 January 2019, which consists of two lobes that appear to have merged at low speed, producing a contact binary.
Abstract: After flying past Pluto in 2015, the New Horizons spacecraft shifted course to encounter (486958) 2014 MU_(69), a much smaller body about 30 kilometers in diameter. MU_(69) is part of the Kuiper Belt, a collection of small icy bodies orbiting in the outer Solar System. Stern et al.present the initial results from the New Horizons flyby of MU_(69) on 1 January 2019. MU_(69) consists of two lobes that appear to have merged at low speed, producing a contact binary. This type of Kuiper Belt object is mostly undisturbed since the formation of the Solar System and so will preserve clues about that process.
120 citations
Search for extraterrestrial intelligence1, Ames Research Center2, Southwest Research Institute3, Massachusetts Institute of Technology4, Lowell Observatory5, Goddard Space Flight Center6, Centre national de la recherche scientifique7, Space Telescope Science Institute8, University of Virginia9, Johns Hopkins University Applied Physics Laboratory10, Northern Arizona University11, University of Sharjah12, University of Texas at Austin13
TL;DR: Using the LEISA (Linear Etalon Imaging Spectral Array) near-IR imaging spectrometer, Stern et al. as discussed by the authors found several sites on Pluto's surface that exhibit the 15, 165 and 20 µm absorption bands characteristic of H2O-ice in the crystalline phase.
33 citations
California Institute of Technology1, Cornell University2, Max Planck Society3, Southwest Research Institute4, University of Potsdam5, University of Arizona6, Free University of Berlin7, University College London8, Heidelberg University9, Johns Hopkins University Applied Physics Laboratory10, University of Stuttgart11, University of Chicago12, University of Colorado Boulder13, University of California, Berkeley14, United States Geological Survey15
TL;DR: The results show that Saturn's rings are substantially younger than the planet itself and constrain models of their origin, and five small moons located close to Saturn’s rings have unusual morphologies, contain water ice, and have accreted ring material.
Abstract: Saturn’s main ring system is associated with a set of small moons that are either embedded within it, or interact with the rings to alter their shape and composition. Five close flybys of the moons Pan, Daphnis, Atlas, Pandora, and Epimetheus were performed between December 2016 and April 2017 during the Ring-grazing Orbits of the Cassini mission. Data on the moons’ morphology, structure, particle environment, and composition were returned, along with images in the ultraviolet and thermal infrared. The optical properties of the moons’ surfaces are determined by two competing processes: contamination by a red material formed in Saturn’s main ring system, and by accretion of bright icy particles or water vapor from volcanic plumes originating on the planet’s moon Enceladus.
33 citations
12 citations
TL;DR: The Pac-Man thermal anomaly was first discovered by Howett et al. as discussed by the authors, who used the composite infrared spectrometer (CIRS) data collected by Tethys' leading hemisphere during a nine-hour time period.
3 citations
TL;DR: In this paper, an aperture optimization technique for extracting photometry of saturated moving targets with high temporally and spatially-varying backgrounds is presented, and the authors find no compelling evidence for signals attributable to atmospheric variation on the timescales sampled by these observations.
Abstract: Motivated by the Kepler K2 time series of Titan, we present an aperture optimization technique for extracting photometry of saturated moving targets with high temporally- and spatially-varying backgrounds. Our approach uses $k$-means clustering to identify interleaved families of images with similar Point-Spread Function and saturation properties, optimizes apertures for each family independently, then merges the time series through a normalization procedure. By applying $k$-means aperture optimization to the K2 Titan data, we achieve $\leq$0.33% photometric scatter in spite of background levels varying from 15% to 60% of the target's flux. We find no compelling evidence for signals attributable to atmospheric variation on the timescales sampled by these observations. We explore other potential applications of the $k$-means aperture optimization technique, including testing its performance on a saturated K2 eclipsing binary star. We conclude with a discussion of the potential for future continuous high-precision photometry campaigns for revealing the dynamical properties of Titan's atmosphere.
2 citations
01 Mar 2019
2 citations
TL;DR: In this paper, an aperture optimization technique for extracting photometry of saturated moving targets with high temporally and spatially-varying backgrounds is presented, and the authors find no compelling evidence for signals attributable to atmospheric variation on the timescales sampled by these observations.
Abstract: Motivated by the Kepler K2 time series of Titan, we present an aperture optimization technique for extracting photometry of saturated moving targets with high temporally- and spatially-varying backgrounds. Our approach uses $k$-means clustering to identify interleaved families of images with similar Point-Spread Function and saturation properties, optimizes apertures for each family independently, then merges the time series through a normalization procedure. By applying $k$-means aperture optimization to the K2 Titan data, we achieve $\leq$0.33% photometric scatter in spite of background levels varying from 15% to 60% of the target's flux. We find no compelling evidence for signals attributable to atmospheric variation on the timescales sampled by these observations. We explore other potential applications of the $k$-means aperture optimization technique, including testing its performance on a saturated K2 eclipsing binary star. We conclude with a discussion of the potential for future continuous high-precision photometry campaigns for revealing the dynamical properties of Titan's atmosphere.