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1. The geology and evolution of the Near-Earth binary asteroid system (65803) Didymos

Author

Olivier Barnouin, Ronald-Louis Ballouz, Simone Marchi, Jean-Baptiste Vincent, Harrison Agrusa, Yun Zhang, Carolyn M. Ernst, Maurizio Pajola, Filippo Tusberti, Alice Lucchetti, R. Terik Daly, Eric Palmer, Kevin J. Walsh, Patrick Michel, Jessica M. Sunshine, Juan L. Rizos, Tony L. Farnham, Derek C. Richardson, Laura M. Parro, Naomi Murdoch, Colas Q. Robin, Masatoshi Hirabayashi, Tomas Kahout, Erik Asphaug, Sabina D. Raducan, Martin Jutzi, Fabio Ferrari, Pedro Henrique Aragao Hasselmann, Adriano CampoBagatin, Nancy L. Chabot, Jian-Yang Li, Andrew F. Cheng, Michael C. Nolan, Angela M. Stickle, Ozgur Karatekin, Elisabetta Dotto, Vincenzo Della Corte, Elena Mazzotta Epifani, Alessandro Rossi, Igor Gai, Jasinghege Don Prasanna Deshapriya, Ivano Bertini, Angelo Zinzi, Josep M. Trigo-Rodriguez, Joel Beccarelli, Stavro Lambrov Ivanovski, John Robert Brucato, Giovanni Poggiali, Giovanni Zanotti, Marilena Amoroso, Andrea Capannolo, Gabriele Cremonese, Massimo Dall’Ora, Simone Ieva, Gabriele Impresario, Michèle Lavagn, Dario Modenini, Pasquale Palumbo, Davide Perna, Simone Pirrotta, Paolo Tortora, Marco Zannoni, and Andrew S. Rivkin

Subjects
Science
Abstract

Abstract Images collected during NASA’s Double Asteroid Redirection Test (DART) mission provide the first resolved views of the Didymos binary asteroid system. These images reveal that the primary asteroid, Didymos, is flattened and has plausible undulations along its equatorial perimeter. At high elevations, its surface is rough and contains large boulders and craters; at low elevations its surface is smooth and possesses fewer large boulders and craters. Didymos’ moon, Dimorphos, possesses an intimate mixture of boulders, several asteroid-wide lineaments, and a handful of craters. The surfaces of both asteroids include boulders that are large relative to their host body, suggesting that both asteroids are rubble piles. Based on these observations, our models indicate that Didymos has a surface cohesion ≤ 1 Pa and an interior cohesion of ∼10 Pa, while Dimorphos has a surface cohesion of

Published
2024
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2. Mechanical properties of rubble pile asteroids (Dimorphos, Itokawa, Ryugu, and Bennu) through surface boulder morphological analysis

Author

Colas Q. Robin, Alexia Duchene, Naomi Murdoch, Jean-Baptiste Vincent, Alice Lucchetti, Maurizio Pajola, Carolyn M. Ernst, R. Terik Daly, Olivier S. Barnouin, Sabina D. Raducan, Patrick Michel, Masatochi Hirabayashi, Alexander Stott, Gabriela Cuervo, Erica R. Jawin, Josep M. Trigo-Rodriguez, Laura M. Parro, Cecily Sunday, Damien Vivet, David Mimoun, Andrew S. Rivkin, and Nancy L. Chabot

Subjects
Science
Abstract

Abstract Planetary defense efforts rely on estimates of the mechanical properties of asteroids, which are difficult to constrain accurately from Earth. The mechanical properties of asteroid material are also important in the interpretation of the Double Asteroid Redirection Test (DART) impact. Here we perform a detailed morphological analysis of the surface boulders on Dimorphos using images, the primary data set available from the DART mission. We estimate the bulk angle of internal friction of the boulders to be 32.7 ± 2. 5° from our measurements of the roundness of the 34 best-resolved boulders ranging in size from 1.67–6.64 m. The elongated nature of the boulders around the DART impact site implies that they were likely formed through impact processing. Finally, we find striking similarities in the morphology of the boulders on Dimorphos with those on other rubble pile asteroids (Itokawa, Ryugu and Bennu). This leads to very similar internal friction angles across the four bodies and suggests that a common formation mechanism has shaped the boulders. Our results provide key inputs for understanding the DART impact and for improving our knowledge about the physical properties, the formation and the evolution of both near-Earth rubble-pile and binary asteroids.

Published
2024
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3. High-resolution shape models of Phobos and Deimos from stereophotoclinometry

Author

Carolyn M. Ernst, R. Terik Daly, Robert W. Gaskell, Olivier S. Barnouin, Hari Nair, Benjamin A. Hyatt, Manar M. Al Asad, and Kielan K. W. Hoch

Subjects
Phobos, Deimos, Martian moons, Small bodies, Shape, Topography, Geography. Anthropology. Recreation, Geodesy, QB275-343, Geology, QE1-996.5
Abstract

Abstract We created high-resolution shape models of Phobos and Deimos using stereophotoclinometry and united images from Viking Orbiter, Phobos 2, Mars Global Surveyor, Mars Express, and Mars Reconnaissance Orbiter into a single coregistered collection. The best-fit ellipsoid to the Phobos model has radii of (12.95 ± 0.04) km × (11.30 ± 0.04) km × (9.16 ± 0.03) km, with an average radius of (11.08 ± 0.04) km. The best-fit ellipsoid to the Deimos model has radii of (8.04 ± 0.08) km × (5.89 ± 0.06) km × (5.11 ± 0.05) km with an average radius of (6.27 ± 0.07) km. The new shape models offer substantial improvements in resolution over existing shape models, while remaining globally consistent with them. The Phobos model resolves grooves, craters, and other surface features ~ 100 m in size across the entire surface. The Deimos model is the first to resolve geological surface features. These models, associated data products, and a searchable, coregistered collection of images across six spacecraft are publicly available in the Small Body Mapping Tool, and will be archived with the NASA Planetary Data System. These products enable an array of future studies to advance the understanding of Phobos and Deimos, facilitate coregistration of other past and future datasets, and set the stage for planning and operating future missions to the moons, including the upcoming Martian Moons eXploration (MMX) mission. Graphical Abstract

Published
2023
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4. The Dynamical State of the Didymos System before and after the DART Impact

Author

Derek C. Richardson, Harrison F. Agrusa, Brent Barbee, Rachel H. Cueva, Fabio Ferrari, Seth A. Jacobson, Rahil Makadia, Alex J. Meyer, Patrick Michel, Ryota Nakano, Yun Zhang, Paul Abell, Colby C. Merrill, Adriano Campo Bagatin, Olivier Barnouin, Nancy L. Chabot, Andrew F. Cheng, Steven R. Chesley, R. Terik Daly, Siegfried Eggl, Carolyn M. Ernst, Eugene G. Fahnestock, Tony L. Farnham, Oscar Fuentes-Muñoz, Edoardo Gramigna, Douglas P. Hamilton, Masatoshi Hirabayashi, Martin Jutzi, Josh Lyzhoft, Riccardo Lasagni Manghi, Jay McMahon, Fernando Moreno, Naomi Murdoch, Shantanu P. Naidu, Eric E. Palmer, Paolo Panicucci, Laurent Pou, Petr Pravec, Sabina D. Raducan, Andrew S. Rivkin, Alessandro Rossi, Paul Sánchez, Daniel J. Scheeres, Peter Scheirich, Stephen R. Schwartz, Damya Souami, Gonzalo Tancredi, Paolo Tanga, Paolo Tortora, Josep M. Trigo-Rodríguez, Kleomenis Tsiganis, John Wimarsson, and Marco Zannoni

Subjects
Asteroids, Asteroid dynamics, Asteroid satellites, Astronomy, QB1-991
Abstract

NASA’s Double Asteroid Redirection Test (DART) spacecraft impacted Dimorphos, the natural satellite of (65803) Didymos, on 2022 September 26, as a first successful test of kinetic impactor technology for deflecting a potentially hazardous object in space. The experiment resulted in a small change to the dynamical state of the Didymos system consistent with expectations and Level 1 mission requirements. In the preencounter paper, predictions were put forward regarding the pre- and postimpact dynamical state of the Didymos system. Here we assess these predictions, update preliminary findings published after the impact, report on new findings related to dynamics, and provide implications for ESA’s Hera mission to Didymos, scheduled for launch in 2024 October with arrival in 2026 December. Preencounter predictions tested to date are largely in line with observations, despite the unexpected, flattened appearance of Didymos compared to the radar model and the apparent preimpact oblate shape of Dimorphos (with implications for the origin of the system that remain under investigation). New findings include that Dimorphos likely became prolate due to the impact and may have entered a tumbling rotation state. A possible detection of a postimpact transient secular decrease in the binary orbital period suggests possible dynamical coupling with persistent ejecta. Timescales for damping of any tumbling and clearing of any debris are uncertain. The largest uncertainty in the momentum transfer enhancement factor of the DART impact remains the mass of Dimorphos, which will be resolved by the Hera mission.

Published
2024
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5. Science Product Pipelines and Archive Architecture for the DART Mission

Author

C. Dany Waller, Raymond C. Espiritu, Calley Tinsman, Hari Nair, Carolyn M. Ernst, R. Terik Daly, Olivier S. Barnouin, Angelo Zinzi, Nancy L. Chabot, Andrew S. Rivkin, Nicholas Moskovitz, David Osip, Tim Lister, Eileen Ryan, and William Ryan

Subjects
Near-Earth objects, Astronomy data analysis, Astronomy image processing, Flyby missions, Astronomy, QB1-991
Abstract

On 2022 September 26, the Double Asteroid Redirection Test (DART) mission was the first successful demonstration of a kinetic impactor for planetary defense. The DART mission utilized a novel autonomous data processing pipeline architecture to quickly produce and analyze the quality of raw and calibrated images from the camera mounted on board the spacecraft. Optimization of the data processing pipeline allowed the final 150 images prior to impact to be calibrated and delivered to the Investigation Team and the press within 15 minutes of acquisition. A data quality analysis pipeline allowed for rapid identification of detector misconfigurations, missing data, and other adverse events. DART data products, along with data from LICIACube and data from ground observatories, used common file formats to facilitate the development of analysis and archiving software. This architecture is described for future missions with large volumes of data and an emphasis on quick-turnaround applications such as planetary defense.

Published
2024
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6. Achievement of the Planetary Defense Investigations of the Double Asteroid Redirection Test (DART) Mission

Author

Nancy L. Chabot, Andrew S. Rivkin, Andrew F. Cheng, Olivier S. Barnouin, Eugene G. Fahnestock, Derek C. Richardson, Angela M. Stickle, Cristina A. Thomas, Carolyn M. Ernst, R. Terik Daly, Elisabetta Dotto, Angelo Zinzi, Steven R. Chesley, Nicholas A. Moskovitz, Brent W. Barbee, Paul Abell, Harrison F. Agrusa, Michele T. Bannister, Joel Beccarelli, Dmitriy L. Bekker, Megan Bruck Syal, Bonnie J. Buratti, Michael W. Busch, Adriano Campo Bagatin, Joseph P. Chatelain, Sidney Chocron, Gareth S. Collins, Luca Conversi, Thomas M. Davison, Mallory E. DeCoster, J. D. Prasanna Deshapriya, Siegfried Eggl, Raymond C. Espiritu, Tony L. Farnham, Marin Ferrais, Fabio Ferrari, Dora Föhring, Oscar Fuentes-Muñoz, Igor Gai, Carmine Giordano, David A. Glenar, Edward Gomez, Dawn M. Graninger, Simon F. Green, Sarah Greenstreet, Pedro H. Hasselmann, Isabel Herreros, Masatoshi Hirabayashi, Marek Husárik, Simone Ieva, Stavro L. Ivanovski, Samuel L. Jackson, Emmanuel Jehin, Martin Jutzi, Ozgur Karatekin, Matthew M. Knight, Ludmilla Kolokolova, Kathryn M. Kumamoto, Michael Küppers, Fiorangela La Forgia, Monica Lazzarin, Jian-Yang Li, Tim A. Lister, Ramin Lolachi, Michael P. Lucas, Alice Lucchetti, Robert Luther, Rahil Makadia, Elena Mazzotta Epifani, Jay McMahon, Gianmario Merisio, Colby C. Merrill, Alex J. Meyer, Patrick Michel, Marco Micheli, Alessandra Migliorini, Kate Minker, Dario Modenini, Fernando Moreno, Naomi Murdoch, Brian Murphy, Shantanu P. Naidu, Hari Nair, Ryota Nakano, Cyrielle Opitom, Jens Ormö, J. Michael Owen, Maurizio Pajola, Eric E. Palmer, Pasquale Palumbo, Paolo Panicucci, Laura M. Parro, Jason M. Pearl, Antti Penttilä, Davide Perna, Elisabeta Petrescu, Petr Pravec, Sabina D. Raducan, K. T. Ramesh, Ryan Ridden-Harper, Juan L. Rizos, Alessandro Rossi, Nathan X. Roth, Agata Rożek, Benjamin Rozitis, Eileen V. Ryan, William H. Ryan, Paul Sánchez, Toni Santana-Ros, Daniel J. Scheeres, Peter Scheirich, Cem Berk Senel, Colin Snodgrass, Stefania Soldini, Damya Souami, Thomas S. Statler, Rachel Street, Timothy J. Stubbs, Jessica M. Sunshine, Nicole J. Tan, Gonzalo Tancredi, Calley L. Tinsman, Paolo Tortora, Filippo Tusberti, James D. Walker, C. Dany Waller, Kai Wünnemann, Marco Zannoni, and Yun Zhang

Subjects
Asteroids, Small Solar System bodies, Near-Earth objects, Asteroid satellites, Planetary science, Solar system astronomy, Astronomy, QB1-991
Abstract

NASA's Double Asteroid Redirection Test (DART) mission was the first to demonstrate asteroid deflection, and the mission's Level 1 requirements guided its planetary defense investigations. Here, we summarize DART's achievement of those requirements. On 2022 September 26, the DART spacecraft impacted Dimorphos, the secondary member of the Didymos near-Earth asteroid binary system, demonstrating an autonomously navigated kinetic impact into an asteroid with limited prior knowledge for planetary defense. Months of subsequent Earth-based observations showed that the binary orbital period was changed by –33.24 minutes, with two independent analysis methods each reporting a 1 σ uncertainty of 1.4 s. Dynamical models determined that the momentum enhancement factor, β , resulting from DART's kinetic impact test is between 2.4 and 4.9, depending on the mass of Dimorphos, which remains the largest source of uncertainty. Over five dozen telescopes across the globe and in space, along with the Light Italian CubeSat for Imaging of Asteroids, have contributed to DART's investigations. These combined investigations have addressed topics related to the ejecta, dynamics, impact event, and properties of both asteroids in the binary system. A year following DART's successful impact into Dimorphos, the mission has achieved its planetary defense requirements, although work to further understand DART's kinetic impact test and the Didymos system will continue. In particular, ESA's Hera mission is planned to perform extensive measurements in 2027 during its rendezvous with the Didymos–Dimorphos system, building on DART to advance our knowledge and continue the ongoing international collaboration for planetary defense.

Published
2024
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7. An Updated Shape Model of Dimorphos from DART Data

Author

R. Terik Daly, Carolyn M. Ernst, Olivier S. Barnouin, Robert W. Gaskell, Hari Nair, Harrison Agrusa, Nancy L. Chabot, Andrew F. Cheng, Elisabetta Dotto, Elena Mazzotta Epifani, Raymond C. Espiritu, Tony L. Farnham, Eric E. Palmer, Petr Pravec, Andrew S. Rivkin, Dany C. Waller, Angelo Zinzi, and the DART and LICIACube teams

Subjects
Asteroid surfaces, Near-Earth objects, Asteroid satellites, Space research, Astronomy, QB1-991
Abstract

Dimorphos was the target of the Double Asteroid Redirection Test (DART) mission. This paper summarizes the properties of an updated shape model of Dimorphos, describes the differences between the updated shape model and an earlier version published by Daly, Ernst, Barnouin et al. (doi: https://doi.org/10.1038/s41586-023-05810-5 ), summarizes the data products associated with this model, and explains where the products can be accessed. The updated shape model benefited from improved methods of incorporating limb information, which will accelerate future shape modeling efforts for other objects with limited imaging data. The updated shape model is similar to the earlier model but slightly smaller (−2.8% change in volume) than the previous Dimorphos global shape model, and the updated shape is slightly more elongated. The additional analysis reported here supports an oblate preimpact shape for Dimorphos. This result indicates that the postimpact elongation of Dimorphos derived from ground-based observations is evidence for a large crater or global reshaping of the asteroid due to the DART impact. The updated global shape model of Dimorphos, as well as the earlier version, will be available in the Planetary Data System Small Bodies Node and through the public Small Body Mapping Tool.

Published
2024
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8. MEGANE investigations of Phobos and the Small Body Mapping Tool

Author

Nancy L. Chabot, Patrick N. Peplowski, Carolyn M. Ernst, Hari Nair, Michael Lucks, R. Josh Steele, and David J. Lawrence

Subjects
Phobos, MMX, MEGANE, Gamma-ray spectroscopy, Neutron spectroscopy, Martian moons, Geography. Anthropology. Recreation, Geodesy, QB275-343, Geology, QE1-996.5
Abstract

Abstract The MEGANE instrument onboard the MMX mission will acquire gamma-ray and neutron spectroscopy data of Phobos to determine the elemental composition of the martian moon and provide key constraints on its origin. To produce accurate compositional results, the irregular shape of Phobos and its proximity to Mars must be taken into account during the analysis of MEGANE data. The MEGANE team is adapting the Small Body Mapping Tool (SBMT) to handle gamma-ray and neutron spectroscopy investigations, building on the demonstrated record of success of the SBMT being applied to scientific investigations on other spacecraft missions of irregularly shaped bodies. This is the first application of the SBMT to a gamma-ray and neutron spectroscopy dataset, and the native, three-dimensional foundation of the SBMT is well suited to MEGANE’s needs. In addition, the SBMT will enable comparisons between the MEGANE datasets and other datasets of the martian moons, including data from previous spacecraft missions and MMX’s multi-instrument suite.

Published
2021
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9. The Perturbed Full Two-body Problem: Application to Post-DART Didymos

Author

Alex J. Meyer, Harrison F. Agrusa, Derek C. Richardson, R. Terik Daly, Oscar Fuentes-Muñoz, Masatoshi Hirabayashi, Patrick Michel, Colby C. Merrill, Ryota Nakano, Andrew F. Cheng, Brent Barbee, Olivier S. Barnouin, Steven R. Chesley, Carolyn M. Ernst, Ioannis Gkolias, Nicholas A. Moskovitz, Shantanu P. Naidu, Petr Pravec, Petr Scheirich, Cristina A. Thomas, Kleomenis Tsiganis, and Daniel J. Scheeres

Subjects
Asteroid dynamics, Asteroid satellites, Near-Earth objects, Small Solar System bodies, Gravitational interaction, Astronomy, QB1-991
Abstract

With the successful impact of the NASA Double Asteroid Redirection Test (DART) spacecraft in the Didymos–Dimorphos binary asteroid system, we provide an initial analysis of the post-impact perturbed binary asteroid dynamics. To compare our simulation results with observations, we introduce a set of “observable elements” calculated using only the physical separation of the binary asteroid, rather than traditional Keplerian elements. Using numerical methods that treat the fully spin–orbit-coupled dynamics, we estimate the system’s mass and the impact-induced changes in orbital velocity, semimajor axis, and eccentricity. We find that the changes to the mutual orbit depend strongly on the separation distance between Didymos and Dimorphos at the time of impact. If Dimorphos enters a tumbling state after the impact, this may be observable through changes in the system’s eccentricity and orbit period. We also find that any DART-induced reshaping of Dimorphos would generally reduce the required change in orbital velocity to achieve the measured post-impact orbit period, and will be assessed by the ESA Hera mission in 2027.

Published
2023
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10. Measuring the Elemental Composition of Phobos: The Mars‐moon Exploration with GAmma rays and NEutrons (MEGANE) Investigation for the Martian Moons eXploration (MMX) Mission

Author

David J. Lawrence, Patrick N. Peplowski, Andrew W. Beck, Morgan T. Burks, Nancy L. Chabot, Michael J. Cully, Richard C. Elphic, Carolyn M. Ernst, Samuel Fix, John O. Goldsten, Erin M. Hoffer, Hiroki Kusano, Scott L. Murchie, Brian C. Schratz, Tomohiro Usui, and Zachary W. Yokley

Subjects
composition, Deimos, formation, gamma ray, neutron, Phobos, Astronomy, QB1-991, Geology, QE1-996.5
Abstract

Abstract The Mars‐moon Exploration with GAmma rays and NEutrons (MEGANE) investigation will use gamma‐ray and neutron spectroscopy to measure the elemental composition of Mars' moon Phobos. MEGANE is part of the Japanese Martian Moons eXploration (MMX) mission that will make comprehensive remote sensing measurements of both of Mars' moons Phobos and Deimos. MMX will also return to Earth regolith samples of Phobos. The science goals of the MEGANE investigation mirror those of the MMX mission. MEGANE will use elemental composition measurements to determine if Phobos is a captured asteroid or the end result of a giant impact event on Mars, study Phobos surface processes, provide reconnaissance to support the sample site selection, and supply compositional context for the returned samples. To accomplish its measurements, MEGANE will use a high‐purity Ge gamma‐ray spectrometer (GRS), and a neutron spectrometer (NS) that consists of two 3He gas proportional neutron sensors. The GRS derives heritage from similar instruments from NASA's MErcury Surface, Space ENvironment, GEochemistry, and Ranging mission and the Psyche mission that is currently in development; the NS is based on similar instruments used for NASA's Lunar Prospector and Psyche missions.

Published
2019
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11. Asteroid Ryugu before the Hayabusa2 encounter

Author

Koji Wada, Matthias Grott, Patrick Michel, Kevin J. Walsh, Antonella M. Barucci, Jens Biele, Jürgen Blum, Carolyn M. Ernst, Jan Thimo Grundmann, Bastian Gundlach, Axel Hagermann, Maximilian Hamm, Martin Jutzi, Myung-Jin Kim, Ekkehard Kührt, Lucille Le Corre, Guy Libourel, Roy Lichtenheldt, Alessandro Maturilli, Scott R. Messenger, Tatsuhiro Michikami, Hideaki Miyamoto, Stefano Mottola, Thomas Müller, Akiko M. Nakamura, Larry R. Nittler, Kazunori Ogawa, Tatsuaki Okada, Ernesto Palomba, Naoya Sakatani, Stefan E. Schröder, Hiroki Senshu, Driss Takir, Michael E. Zolensky, and International Regolith Science Group (IRSG) in Hayabusa2 project

Subjects
Hayabusa2, Ryugu, Asteroids, Regolith, Physical properties, Geography. Anthropology. Recreation, Geology, QE1-996.5
Abstract

Abstract Asteroid (162173) Ryugu is the target object of Hayabusa2, an asteroid exploration and sample return mission led by Japan Aerospace Exploration Agency (JAXA). Ground-based observations indicate that Ryugu is a C-type near-Earth asteroid with a diameter of less than 1 km, but the knowledge of its detailed properties is very limited prior to Hayabusa2 observation. This paper summarizes our best understanding of the physical and dynamical properties of Ryugu based on ground-based remote sensing and theoretical modeling before the Hayabusa2’s arrival at the asteroid. This information is used to construct a design reference model of the asteroid that is used for the formulation of mission operation plans in advance of asteroid arrival. Particular attention is given to the surface properties of Ryugu that are relevant to sample acquisition. This reference model helps readers to appropriately interpret the data that will be directly obtained by Hayabusa2 and promotes scientific studies not only for Ryugu itself and other small bodies but also for the solar system evolution that small bodies shed light on.

Published
2018
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12. Ejecta from the DART-produced active asteroid Dimorphos

Author

Jian-Yang Li, Masatoshi Hirabayashi, Tony L. Farnham, Jessica M. Sunshine, Matthew M. Knight, Gonzalo Tancredi, Fernando Moreno, Brian Murphy, Cyrielle Opitom, Steve Chesley, Daniel J. Scheeres, Cristina A. Thomas, Eugene G. Fahnestock, Andrew F. Cheng, Linda Dressel, Carolyn M. Ernst, Fabio Ferrari, Alan Fitzsimmons, Simone Ieva, Stavro L. Ivanovski, Theodore Kareta, Ludmilla Kolokolova, Tim Lister, Sabina D. Raducan, Andrew S. Rivkin, Alessandro Rossi, Stefania Soldini, Angela M. Stickle, Alison Vick, Jean-Baptiste Vincent, Harold A. Weaver, Stefano Bagnulo, Michele T. Bannister, Saverio Cambioni, Adriano Campo Bagatin, Nancy L. Chabot, Gabriele Cremonese, R. Terik Daly, Elisabetta Dotto, David A. Glenar, Mikael Granvik, Pedro H. Hasselmann, Isabel Herreros, Seth Jacobson, Martin Jutzi, Tomas Kohout, Fiorangela La Forgia, Monica Lazzarin, Zhong-Yi Lin, Ramin Lolachi, Alice Lucchetti, Rahil Makadia, Elena Mazzotta Epifani, Patrick Michel, Alessandra Migliorini, Nicholas A. Moskovitz, Jens Ormö, Maurizio Pajola, Paul Sánchez, Stephen R. Schwartz, Colin Snodgrass, Jordan Steckloff, Timothy J. Stubbs, Josep M. Trigo-Rodríguez, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), CNRS through the MITI interdisciplinary programmes, CNES, ESA, European Project: 870377,NEO-MAPP, Universidad de Alicante. Departamento de Física, Ingeniería de Sistemas y Teoría de la Señal, Universidad de Alicante. Instituto Universitario de Física Aplicada a las Ciencias y las Tecnologías, Astronomía y Astrofísica, European Commission, and Ministerio de Ciencia e Innovación (España)

Subjects
asteroids, Ejecta, 530 Physics, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], FOS: Physical sciences, Kuiper belt, Astronomi, astrofysik och kosmologi, Dimorphos, Comets, Astronomy, Astrophysics and Cosmology, Geología, General, planetary defense, Earth and Planetary Astrophysics (astro-ph.EP), Ingeniería Mecánica, Multidisciplinary, Astrophysical dust, 520 Astronomy, 620 Engineering, Asteroids, Astronomía, Impact, [SDU]Sciences of the Universe [physics], DART, Astrophysics - Earth and Planetary Astrophysics
Abstract

Some active asteroids have been proposed to be the result of impact events. Because active asteroids are generally discovered serendipitously only after their tail formation, the process of the impact ejecta evolving into a tail has never been directly observed. NASA's Double Asteroid Redirection Test (DART) mission, apart from having successfully changed the orbital period of Dimorphos, demonstrated the activation process of an asteroid from an impact under precisely known impact conditions. Here we report the observations of the DART impact ejecta with the Hubble Space Telescope (HST) from impact time T+15 minutes to T+18.5 days at spatial resolutions of ~2.1 km per pixel. Our observations reveal a complex evolution of ejecta, which is first dominated by the gravitational interaction between the Didymos binary system and the ejected dust and later by solar radiation pressure. The lowest-speed ejecta dispersed via a sustained tail that displayed a consistent morphology with previously observed asteroid tails thought to be produced by impact. The ejecta evolution following DART's controlled impact experiment thus provides a framework for understanding the fundamental mechanisms acting on asteroids disrupted by natural impact., accepted by Nature

Published
2023

15. Science Goals and Mission Concept for a Landed Investigation of Mercury

Author

Carolyn M. Ernst, Nancy L. Chabot, Rachel L. Klima, Sanae Kubota, Gabe Rogers, Paul K. Byrne, Steven A. Hauck, Kathleen E. Vander Kaaden, Ronald J. Vervack, Sébastien Besse, David T. Blewett, Brett W. Denevi, Sander Goossens, Stephen J. Indyk, Noam R. Izenberg, Catherine L. Johnson, Lauren M. Jozwiak, Haje Korth, Ralph L. McNutt, Scott L. Murchie, Patrick N. Peplowski, Jim M. Raines, Elizabeth B. Rampe, Michelle S. Thompson, and Shoshana Z. Weider

Published
2022
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16. Mercury Lander: Transformative Science from the Surface of the Innermost Planet

Author

Carolyn M. Ernst, Sanae Kubota, Nancy L. Chabot, Rachel Klima, Kathleen Vander Kaaden, Stephen Indyk, Patrick Peplowski, Elizabeth Rampe, Steven A. Hauck, II, Sander Goossens, Catherine Johnson, Haje Korth, Ronald J. Vervack, Jr, David Blewett, Jim Raines, Michelle Thompson, Paul Byrne, Brett Denevi, Noam Izenberg, Lauren Jozwiak, Sebastien Besse, Ralph L. McNutt, Jr, and Scott Murchie

Subjects
Spacecraft Design, Testing And Performance
Abstract

As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of solar system development and how planets and exoplanets form and evolve in close proximity to their host stars. This Mercury Lander mission concept enables in situ surface measurements that address several fundamental science questions raised by MESSENGER’s pioneering exploration of Mercury. Such measurements are needed to understand Mercury’s unique mineralogy and geochemistry; to characterize the proportionally massive core’s structure; to measure the planet’s active and ancient magnetic fields at the surface; to investigate the processes that alter the surface and produce the exosphere; and to provide ground truth for current and future remote datasets. NASA’s Planetary Mission Concept Studies (PMCS) program awarded this study to a multidisciplinary team led by Dr. Carolyn Ernst of the Johns Hopkins Applied Physics Laboratory (APL), to evaluate the feasibility of accomplishing transformative science through a New-Frontiers-class, landed mission to Mercury in the next decade. The resulting mission concept achieves one full Mercury year (~88 Earth days) of surface operations with an ambitious, high-heritage, landed science payload, corresponding well with the New Frontiers mission framework.

Published
2020

19. Momentum Transfer from the DART Mission Kinetic Impact on Asteroid Dimorphos

Author

Andrew F. Cheng, Harrison F. Agrusa, Brent W. Barbee, Alex J. Meyer, Tony L. Farnham, Sabina D. Raducan, Derek C. Richardson, Elisabetta Dotto, Angelo Zinzi, Vincenzo Della Corte, Thomas S. Statler, Steven Chesley, Shantanu P. Naidu, Masatoshi Hirabayashi, Jian-Yang Li, Siegfried Eggl, Olivier S. Barnouin, Nancy L. Chabot, Sidney Chocron, Gareth S. Collins, R. Terik Daly, Thomas M. Davison, Mallory E. DeCoster, Carolyn M. Ernst, Fabio Ferrari, Dawn M. Graninger, Seth A. Jacobson, Martin Jutzi, Kathryn M. Kumamoto, Robert Luther, Joshua R. Lyzhoft, Patrick Michel, Naomi Murdoch, Ryota Nakano, Eric Palmer, Andrew S. Rivkin, Daniel J. Scheeres, Angela M. Stickle, Jessica M. Sunshine, Josep M. Trigo-Rodriguez, Jean-Baptiste Vincent, James D. Walker, Kai Wünnemann, Yun Zhang, Marilena Amoroso, Ivano Bertini, John R. Brucato, Andrea Capannolo, Gabriele Cremonese, Massimo Dall’Ora, Prasanna J. D. Deshapriya, Igor Gai, Pedro H. Hasselmann, Simone Ieva, Gabriele Impresario, Stavro L. Ivanovski, Michèle Lavagna, Alice Lucchetti, Elena M. Epifani, Dario Modenini, Maurizio Pajola, Pasquale Palumbo, Davide Perna, Simone Pirrotta, Giovanni Poggiali, Alessandro Rossi, Paolo Tortora, Marco Zannoni, Giovanni Zanotti, Cheng A.F., Agrusa H.F., Barbee B.W., Meyer A.J., Farnham T.L., Raducan S.D., Richardson D.C., Dotto E., Zinzi A., Della Corte V., Statler T.S., Chesley S., Naidu S.P., Hirabayashi M., Li J.Y., Eggl S., Barnouin O.S., Chabot N.L., Chocron S., Collins G.S., Daly R.T., Davison T.M., DeCoster M.E., Ernst C.M., Ferrari F., Graninger D.M., Jacobson S.A., Jutzi M., Kumamoto K.M., Luther R., Lyzhoft J.R., Michel P., Murdoch N., Nakano R., Palmer E., Rivkin A.S., Scheeres D.J., Stickle A.M., Sunshine J.M., Trigo-Rodriguez J.M., Vincent J.B., Walker J.D., Wünnemann K., Zhang Y., Amoroso M., Bertini I., Brucato J.R., Capannolo A., Cremonese G., Dall’Ora M., Deshapriya P.J.D., Gai I., Hasselmann P.H., Ieva S., Impresario G., Ivanovski S.L., Lavagna M., Lucchetti A., Epifani E.M., Modenini D., Pajola M., Palumbo P., Perna D., Pirrotta S., Poggiali G., Rossi A., Tortora P., Zannoni M., Zanotti G., Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), CNRS through the MITI interdisciplinary programmes, CNES, ESA, and European Project: 870377,NEO-MAPP

Subjects
asteroids, bulk density, geometry, 530 Physics, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], kinetic, FOS: Physical sciences, satellite imagery, size, Article, motion, ma, controlled study, uncertainty, planetary defense, Earth and Planetary Astrophysics (astro-ph.EP), Multidisciplinary, asteroid, 520 Astronomy, momentum transfer, 620 Engineering, astronomy, preliminary data, [SDU]Sciences of the Universe [physics], DART, Astrophysics - Earth and Planetary Astrophysics
Abstract

The NASA Double Asteroid Redirection Test (DART) mission performed a kinetic impact on asteroid Dimorphos, the satellite of the binary asteroid (65803) Didymos, at 23:14 UTC on September 26, 2022 as a planetary defense test. DART was the first hypervelocity impact experiment on an asteroid at size and velocity scales relevant to planetary defense, intended to validate kinetic impact as a means of asteroid deflection. Here we report the first determination of the momentum transferred to an asteroid by kinetic impact. Based on the change in the binary orbit period, we find an instantaneous reduction in Dimorphos's along-track orbital velocity component of 2.70 +/- 0.10 mm/s, indicating enhanced momentum transfer due to recoil from ejecta streams produced by the impact. For a Dimorphos bulk density range of 1,500 to 3,300 kg/m$^3$, we find that the expected value of the momentum enhancement factor, $\beta$, ranges between 2.2 and 4.9, depending on the mass of Dimorphos. If Dimorphos and Didymos are assumed to have equal densities of 2,400 kg/m$^3$, $\beta$= 3.61 +0.19/-0.25 (1 $\sigma$). These $\beta$ values indicate that significantly more momentum was transferred to Dimorphos from the escaping impact ejecta than was incident with DART. Therefore, the DART kinetic impact was highly effective in deflecting the asteroid Dimorphos., Comment: accepted by Nature

Published
2023
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20. Successful Kinetic Impact into an Asteroid for Planetary Defense

Author

R. Terik Daly, Carolyn M. Ernst, Olivier S. Barnouin, Nancy L. Chabot, Andrew S. Rivkin, Andrew F. Cheng, Elena Y. Adams, Harrison F. Agrusa, Elisabeth D. Abel, Amy L. Alford, Erik I. Asphaug, Justin A. Atchison, Andrew R. Badger, Paul Baki, Ronald-L. Ballouz, Dmitriy L. Bekker, Julie Bellerose, Shyam Bhaskaran, Bonnie J. Buratti, Saverio Cambioni, Michelle H. Chen, Steven R. Chesley, George Chiu, Gareth S. Collins, Matthew W. Cox, Mallory E. DeCoster, Peter S. Ericksen, Raymond C. Espiritu, Alan S. Faber, Tony L. Farnham, Fabio Ferrari, Zachary J. Fletcher, Robert W. Gaskell, Dawn M. Graninger, Musad A. Haque, Patricia A. Harrington-Duff, Sarah Hefter, Isabel Herreros, Masatoshi Hirabayashi, Philip M. Huang, Syau-Yun W. Hsieh, Seth A. Jacobson, Stephen N. Jenkins, Mark A. Jensenius, Jeremy W. John, Martin Jutzi, Tomas Kohout, Timothy O. Krueger, Frank E. Laipert, Norberto R. Lopez, Robert Luther, Alice Lucchetti, Declan M. Mages, Simone Marchi, Anna C. Martin, Maria E. McQuaide, Patrick Michel, Nicholas A. Moskovitz, Ian W. Murphy, Naomi Murdoch, Shantanu P. Naidu, Hari Nair, Michael C. Nolan, Jens Ormö, Maurizio Pajola, Eric E. Palmer, James M. Peachey, Petr Pravec, Sabina D. Raducan, K. T. Ramesh, Joshua R. Ramirez, Edward L. Reynolds, Joshua E. Richman, Colas Q. Robin, Luis M. Rodriguez, Lew M. Roufberg, Brian P. Rush, Carolyn A. Sawyer, Daniel J. Scheeres, Petr Scheirich, Stephen R. Schwartz, Matthew P. Shannon, Brett N. Shapiro, Caitlin E. Shearer, Evan J. Smith, R. Joshua Steele, Jordan K. Steckloff, Angela M. Stickle, Jessica M. Sunshine, Emil A. Superfin, Zahi B. Tarzi, Cristina A. Thomas, Justin R. Thomas, Josep M. Trigo-Rodríguez, B. Teresa Tropf, Andrew T. Vaughan, Dianna Velez, C. Dany Waller, Daniel S. Wilson, Kristin A. Wortman, Yun Zhang, Joseph Louis LAGRANGE (LAGRANGE), Université Nice Sophia Antipolis (1965 - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Université Côte d'Azur (UCA)-Centre National de la Recherche Scientifique (CNRS), European Commission’s Horizon 2020 research and innovation programme under grant agreement no. 870377 (NEO-MAPP project), CNES, CNRS through the MITI interdisciplinary programmes, ESA, European Project: 870377,NEO-MAPP, European Commission, and Ministerio de Ciencia e Innovación (España)

Subjects
Ingeniería Mecánica, Earth and Planetary Astrophysics (astro-ph.EP), Multidisciplinary, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 530 Physics, 520 Astronomy, Física, FOS: Physical sciences, 620 Engineering, Asteroids, Kuiper belt, Astronomía, [SDU]Sciences of the Universe [physics], Meteoritics, Fisión, Comets, Geología, Astrophysics - Earth and Planetary Astrophysics
Abstract

While no known asteroid poses a threat to Earth for at least the next century, the catalog of near-Earth asteroids is incomplete for objects whose impacts would produce regional devastation. Several approaches have been proposed to potentially prevent an asteroid impact with Earth by deflecting or disrupting an asteroid. A test of kinetic impact technology was identified as the highest priority space mission related to asteroid mitigation. NASA's Double Asteroid Redirection Test (DART) mission is the first full-scale test of kinetic impact technology. The mission's target asteroid was Dimorphos, the secondary member of the S-type binary near-Earth asteroid (65803) Didymos. This binary asteroid system was chosen to enable ground-based telescopes to quantify the asteroid deflection caused by DART's impact. While past missions have utilized impactors to investigate the properties of small bodies those earlier missions were not intended to deflect their targets and did not achieve measurable deflections. Here we report the DART spacecraft's autonomous kinetic impact into Dimorphos and reconstruct the impact event, including the timeline leading to impact, the location and nature of the DART impact site, and the size and shape of Dimorphos. The successful impact of the DART spacecraft with Dimorphos and the resulting change in Dimorphos's orbit demonstrates that kinetic impactor technology is a viable technique to potentially defend Earth if necessary., Comment: Accepted by Nature

Published
2023
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22. Persephone: A Pluto-system Orbiter and Kuiper Belt Explorer

Author

Carly J. A. Howett, Stuart J. Robbins, Bryan J. Holler, Amanda Hendrix, Karl B. Fielhauer, Mark E. Perry, Fazle E. Siddique, Clint T. Apland, James C. Leary, S. Alan Stern, Heather Elliott, Francis Nimmo, Simon B. Porter, Silvia Protopapa, Kelsi N. Singer, Orenthal J. Tucker, Anne J. Verbiscer, Bruce B. Andrews, Stewart S. Bushman, Adam V. Crifasi, Doug Crowley, Clint L. Edwards, Carolyn M. Ernst, Blair D. Fonville, David P. Frankford, Dan T. Gallagher, Mark E. Holdridge, Jack W. Hunt, J. J. Kavelaars, Chris J. Krupiarz, James S. Kuhn, William McKinnon, Hari Nair, David H. Napolillo, Jon P. Pineau, Jani Radebaugh, Rachel O. Sholder, John R. Spencer, Adam Thodey, Samantha R. Walters, Bruce D. Williams, Robert J. Wilson, and Leslie A. Young

Published
2021
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26. Science Goals and Objectives for the Dragonfly Titan Rotorcraft Relocatable Lander

Author

Simon Stähler, E. R. Stofan, Kevin P. Hand, C. D. Neish, William B. Brinckerhoff, Colin Wilson, Ralph D. Lorenz, Scot Rafkin, R. A. Yingst, Tetsuya Tokano, Kris Zacny, Jani Radebaugh, Christopher P. McKay, Patrick N. Peplowski, Alexander Hayes, Erich Karkoschka, Juan M. Lora, Jorge I. Nunez, Jason W. Barnes, Claire E. Newman, Melissa G. Trainer, Alice Le Gall, A. M. Parsons, Caroline Freissinet, Mark P. Panning, Lynnae C. Quick, David J. Lawrence, Carolyn M. Ernst, Cyril Szopa, Thomas P. Wagner, Jeffrey R. Johnson, Hiroaki Shiraishi, R. S. Miller, Kristin S. Sotzen, Sarah M. Hörst, Shannon MacKenzie, Elizabeth P. Turtle, Morgan L. Cable, Scott L. Murchie, Jason M. Soderblom, Angela Stickle, Department of Physics [Moscow,USA], University of Idaho [Moscow, USA], Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), NASA Goddard Space Flight Center (GSFC), Jet Propulsion Laboratory (JPL), NASA-California Institute of Technology (CALTECH), PLANETO - LATMOS, Laboratoire Atmosphères, Milieux, Observations Spatiales (LATMOS), Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Sorbonne Université (SU)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS), Department of Astronomy [Ithaca], Cornell University [New York], Morton K. Blaustein Department of Earth and Planetary Sciences [Baltimore], Johns Hopkins University (JHU), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Department of Earth and Planetary Sciences [New Haven], Yale University [New Haven], NASA Ames Research Center (ARC), Planetary Science Institute [Tucson] (PSI), Department of Earth Sciences [London, ON], University of Western Ontario (UWO), Aeolis Research, Department of Geological Sciences [BYU], Brigham Young University (BYU), Southwest Research Institute [Boulder] (SwRI), Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency [Sagamihara] (JAXA), Department of Earth and Planetary Sciences [Cambridge, USA] (EPS), Harvard University [Cambridge], Smithsonian National Air and Space Museum, Smithsonian Institution, Institut für Geophysik und Meteorologie [Köln], Universität zu Köln, NASA Headquarters, Department of Atmospheric, Oceanic and Planetary Physics [Oxford] (AOPP), University of Oxford [Oxford], Honeybee Robotics Ltd, Institute of Geophysics [ETH Zürich], Department of Earth Sciences [Swiss Federal Institute of Technology - ETH Zürich] (D-ERDW), and Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)- Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich)

Subjects
Aquifer, 01 natural sciences, Mantle (geology), Astrobiology, Pre-biotic astrochemistry, 03 medical and health sciences, symbols.namesake, Extant taxon, Impact crater, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Planetary surfaces, 14. Life underwater, 010303 astronomy & astrophysics, 030304 developmental biology, 0303 health sciences, geography, geography.geographical_feature_category, Habitability, Astronomy and Astrophysics, Prebiotic chemistry, Geophysics, 13. Climate action, Space and Planetary Science, [SDU]Sciences of the Universe [physics], symbols, Water ice, Titan (rocket family), Titan, Planetary atmospheres
Abstract

NASA’s Dragonfly mission will send a rotorcraft lander to the surface of Titan in the mid-2030s. Dragonfly's science themes include investigation of Titan’s prebiotic chemistry, habitability, and potential chemical biosignatures from both water-based “life as we know it” (as might occur in the interior mantle ocean, potential cryovolcanic flows, and/or impact melt deposits) and potential “life, but not as we know it” that might use liquid hydrocarbons as a solvent (within Titan’s lakes, seas, and/or aquifers). Consideration of both of these solvents simultaneously led to our initial landing site in Titan’s equatorial dunes and interdunes to sample organic sediments and water ice, respectively. Ultimately, Dragonfly's traverse target is the 80 km diameter Selk Crater, at 7° N, where we seek previously liquid water that has mixed with surface organics. Our science goals include determining how far prebiotic chemistry has progressed on Titan and what molecules and elements might be available for such chemistry. We will also determine the role of Titan’s tropical deserts in the global methane cycle. We will investigate the processes and processing rates that modify Titan’s surface geology and constrain how and where organics and liquid water can mix on and within Titan. Importantly, we will search for chemical biosignatures indicative of past or extant biological processes. As such, Dragonfly, along with Perseverance, is the first NASA mission to explicitly incorporate the search for signs of life into its mission goals since the Viking landers in 1976.

Published
2021

27. Impact-crater ejecta on Bennu indicate a surface with very low strength

Author

Edward B. Bierhaus, J. A. Seabrook, Patrick Michel, Carolyn M. Ernst, Michael Daly, Olivier S. Barnouin, Dante S. Lauretta, Daniella DellaGiustina, Michael C. Nolan, Josh Emory, William F. Bottke, Catherine Johnson, Dathon Golish, Ronald-Louis Ballouz, Erica Jawin, R. T. Daly, Manar Al Asad, Kevin J. Walsh, and Mark E. Perry

Subjects
Surface (mathematics), Impact crater, Ejecta, Geology, Astrobiology
Abstract

A planetary surface’s resistance to change is generally described as its “strength” (units of stress). The surface strength of small, rubble-pile asteroids, which consist of fragments of larger bodies that were collisionally disrupted, is poorly constrained due to their wide departure from terrestrial analogs. Here, we report the observation of an ejecta deposit surrounding an impact crater that limits the maximum surface strength of the near-Earth rubble-pile asteroid (101955) Bennu. The presence of this deposit implies that ejecta were mobilized with velocities less than the escape velocity of Bennu, 20 cm/s. Because ejecta velocities increase with surface strength, the ejecta deposit can only be explained if the effective strength of the surface material near the crater is exceedingly low, ≤100 Pa. This is three orders of magnitude below values commonly used for asteroid surfaces, but is supported by previous observations of an artificial impact crater on a similar asteroid, Ryugu. Our findings indicate a mobile surface that has likely been renewed multiple times since Bennu’s initial assembly and have far-reaching implications for interpreting observations of Bennu and other rubble piles.

Published
2021

30. Three-axial shape distributions of pebbles, cobbles and boulders smaller than a few meters on asteroid Ryugu

Author

Tatsuhiro Michikami, Axel Hagermann, Tomokatsu Morota, Yasuhiro Yokota, Seitaro Urakawa, Hiroyuki Okamura, Naoya Tanabe, Koki Yumoto, Tatsuki Ebihara, Yuichiro Cho, Carolyn M. Ernst, Masahiko Hayakawa, Masatoshi Hirabayashi, Naru Hirata, Chikatoshi Honda, Rie Honda, Shingo Kameda, Masanori Kanamaru, Hiroshi Kikuchi, Shota Kikuchi, Toru Kouyama, Moe Matsuoka, Hideaki Miyamoto, Takaaki Noguchi, Rina Noguchi, Kazunori Ogawa, Tatsuaki Okada, Naoya Sakatani, Sho Sasaki, Hirotaka Sawada, Chiho Sugimoto, Hidehiko Suzuki, Satoshi Tanaka, Eri Tatsumi, Akira Tsuchiyama, Yuichi Tsuda, Sei-ichiro Watanabe, Manabu Yamada, Makoto Yoshikawa, Kazuo Yoshioka, and Seiji Sugita

Subjects
Space and Planetary Science, Astronomy and Astrophysics
Published
2022

31. Comparison of Areas in Shadow from Imaging and Altimetry in the North Polar Region of Mercury and Implications for Polar Ice Deposits

Author

Ariel N Deutsch, Nancy L Chabot, Erwan Mazarico, Carolyn M Ernst, James W Head, Gregory A Neumann, and Sean C Solomon

Subjects
Lunar And Planetary Science And Exploration, Communications And Radar
Abstract

Earth-based radar observations and results from the MESSENGER mission have provided strong evidence that permanently shadowed regions near Mercury's poles host deposits of water ice. MESSENGER's complete orbital image and topographic datasets enable Mercury's surface to be observed and modeled under an extensive range of illumination conditions. The shadowed regions of Mercury's north polar region from 65 deg N to 90 deg N were mapped by analyzing Mercury Dual Imaging System (MDIS) images and by modeling illumination with Mercury Laser Altimeter (MLA) topographic data. The two independent methods produced strong agreement in identifying shadowed areas. All large radar-bright deposits, those hosted within impact craters greater than or equal to 6 km in diameter, collocate with regions of shadow identified by both methods. However, only approximately 46% of the persistently shadowed areas determined from images and approximately 43% of the permanently shadowed areas derived from altimetry host radar-bright materials. Some sizable regions of shadow that do not host radar-bright deposits experience thermal conditions similar to those that do. The shadowed craters that lack radar-bright materials show a relation with longitude that is not related to the thermal environment, suggesting that the Earth-based radar observations of these locations may have been limited by viewing geometry, but it is also possible that water ice in these locations is insulated by anomalously thick lag deposits or that these shadowed regions do not host water ice.

Published
2016
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32. Geologic History and Crater Morphology of Asteroid (162173) Ryugu

Author

Masatoshi Hirabayashi, Tatsuhiro Michikami, Masahiko Hayakawa, Masanori Kanamaru, Moe Matsuoka, Seiji Sugita, Hirotaka Sawada, Koki Yumoto, Eri Tatsumi, Tomokatsu Morota, Roland Wagner, Rie Honda, Shingo Kameda, Hidehiko Suzuki, Chikatoshi Honda, Hiroshi Kikuchi, Naoya Sakatani, Kazunori Ogawa, Nicole Schmitz, Manabu Yamada, Yuichiro Cho, Hideaki Miyamoto, Yasuhiro Yokota, Kazuo Yoshioka, Toru Kouyama, N. Takaki, Naru Hirata, Ryodo Hemmi, Katharina A. Otto, Olivier S. Barnouin, Carolyn M. Ernst, and Ralf Jaumann

Subjects
Morphology, Spacecraft, business.industry, Asteroid, Hayabusa-2, Astrobiology, Geophysics, Space and Planetary Science, Geochemistry and Petrology, Crater morphology, Earth and Planetary Sciences (miscellaneous), Geologic history, Crater, Ryugu, business, Geology
Abstract

Crater morphology and surface age of asteroid (162173) Ryugu are characterized using the high-resolution images obtained by the Hayabusa2 spacecraft. Our observations reveal that the abundant bould...

Published
2021

33. Using dust shed from asteroids as microsamples to link remote measurements with meteorite classes

Author

Nancy L. Chabot, Barbara A. Cohen, Mihaly Horanyi, Zoltan Sternovsky, Jamey Szalay, Carolyn M. Ernst, Rachel L. Klima, Andrew S. Rivkin, and Jacob Richardson

Subjects
Earth and Planetary Astrophysics (astro-ph.EP), FOS: Physical sciences, Radius, 010502 geochemistry & geophysics, 01 natural sciences, Article, Parent body, Characterization (materials science), Astrobiology, Geophysics, Meteorite, Space and Planetary Science, Asteroid, Primary (astronomy), 0103 physical sciences, 010303 astronomy & astrophysics, Achondrite, Geology, Astrophysics - Earth and Planetary Astrophysics, 0105 earth and related environmental sciences, Ordinary chondrite
Abstract

Given the compositional diversity of asteroids, and their distribution in space, it is impossible to consider returning samples from each one to establish their origin. However, the velocity and molecular composition of primary minerals, hydrated silicates, and organic materials can be determined by in situ dust detector instruments. Such instruments could sample the cloud of micrometer-scale particles shed by asteroids to provide direct links to known meteorite groups without returning the samples to terrestrial laboratories. We extend models of the measured lunar dust cloud from LADEE to show that the abundance of detectable impact-generated microsamples around asteroids is a function of the parent body radius, heliocentric distance, flyby distance, and speed. We use monte carlo modeling to show that several tens to hundreds of particles, if randomly ejected and detected during a flyby, would be a sufficient number to classify the parent body as an ordinary chondrite, basaltic achondrite, or other class of meteorite. Encountering and measuring microsamples shed from near-earth and main-belt asteroids, coupled with complementary imaging and multispectral measurements, could accomplish a thorough characterization of small, airless bodies., 19 pages, 3 Tables, 10 Figures, accepted May 30, 2019

Published
2019

34. Examining the Potential Contribution of the Hokusai Impact to Water Ice on Mercury

Author

Olivier S. Barnouin, Nancy L. Chabot, and Carolyn M. Ernst

Subjects
010504 meteorology & atmospheric sciences, chemistry.chemical_element, 01 natural sciences, Mercury (element), Geophysics, chemistry, Impact crater, Space and Planetary Science, Geochemistry and Petrology, Environmental chemistry, 0103 physical sciences, Earth and Planetary Sciences (miscellaneous), Water ice, 010303 astronomy & astrophysics, Geology, 0105 earth and related environmental sciences
Published
2018

36. Mercury sample return to revolutionize our understanding of the solar system

Author

Carolyn M. Ernst, Catherine L. Johnson, Francis M. McCubbin, Paul K. Byrne, Michelle S. Thompson, Kathleen E. Vander Kaaden, and Nancy L. Chabot

Subjects
Solar System, chemistry, Environmental chemistry, chemistry.chemical_element, Environmental science, Sample (graphics), Mercury (element)
Published
2021

37. Apophis 2029 Planetary Defense Mission Options

Author

J. M. Sunshine, Derek C. Richardson, Andrew F. Cheng, Richard P. Binzel, R. T. Daly, Brett W. Denevi, Nicholas Schmerr, J. V. DeMartini, Olivier S. Barnouin, Carolyn M. Ernst, Joshua T.S. Cahill, and J. B. Plescia

Published
2021

39. The Case for a Planetary Defense-Optimized NEO Characterization Tour

Author

Daniel J. Scheeres, Justin A. Atchison, Derek C. Richardson, Terik Daly, Andrew S. Rivkin, Carolyn M. Ernst, Paul A. Abell, Stefanie N. Milam, Olivier S. Barnouin, Angela Stickle, Brent W. Barbee, Thomas Sotirelis, D. Graninger, Patrick K. King, Cristina A. Thomas, and Benjamin T. Greenhagen

Subjects
Engineering, business.industry, Systems engineering, business, Characterization (materials science)
Published
2021

40. Science Opportunities offered by Mercury’s Ice-Bearing Polar Deposits

Author

James W. Head, Cesare Grava, S. S. Bhiravarasu, Jacob L. Kloos, Ariel N. Deutsch, Nancy L. Chabot, William M. Farrell, Mike Sori, Ross W. K. Potter, Kristen M. Luchsinger, Thomas M. Orlando, Paul O. Hayne, Kelly E. Miller, Martin A. Slade, Craig Hardgrove, Carolyn M. Ernst, Anthony Colaprete, Maria Gritsevich, Peter B. James, Erwan Mazarico, Paul K. Byrne, Alice Lucchetti, Menelaos Sarantos, A. K. Virkki, Matthew A. Siegler, Mona Delitsky, Brant M. Jones, Maurizio Pajola, Valentin Tertius Bickel, David T. Blewett, Carl Schmidt, Gregory A. Neumann, Steven A. Hauck, Paul G. Lucey, Gianrico Filacchione, Audrey Vorburger, Parvathy Prem, Timothy J. Stubbs, Abhisek Maiti, B. A. Anzures, Giovanni Bacon, Adrienn Luspay-Kuti, John Wilson, K. M. Cannon, Jamey Szalay, Vincent R. Eke, Jordan K. Steckloff, Michael J. Poston, D. C. Hickson, David J. Lawrence, Edgard G. Rivera-Valentín, Lior Rubanenko, Petr Pokorny, Hannah C.M. Susorney, Holly Brown, Noemi Pinilla-Alonso, Christian Klimczak, Ronald J. Vervack, Shashwat Shukla, Colin D. Hamill, Ákos Kereszturi, Mark A. Schneegurt, Sean C. Solomon, Chuanfei Dong, Norbert Schorghofer, Rosemary M. Killen, E. S. Costello, Indhu Varatharajan, Ben Byron, Margaret E. Landis, L. O. Magana, and Bryan J. Butler

Subjects
Bearing (mechanical), chemistry, law, Geochemistry, Polar, chemistry.chemical_element, Geology, law.invention, Mercury (element)
Published
2021

41. Planetary and Astrobiology Blank Papers: Science White Papers Cancelled or Downscaled Due to Direct Impact of COVID-19 and National-scale Civil Action

Author

Christina Richey, Monica Vidaurri, Ingrid Daubar, Padma A. Yanamandra-Fisher, Kathleen Mandt, Nicolle E. B. Zellner, James Tuttle Keane, Giada Arney, Steven D. Vance, Stuart J. Robbins, Mohit Melwani Daswani, Karalee K. Brugman, Luc Riesbeck, James H. Roberts, Lori M. Feaga, Lillian R. Ostrach, Maitrayee Bose, Michael W. Busch, Ryan Watkins, Jennifer E.C. Scully, R. Terik Daly, Ana Maria Tarano, Carolyn M. Ernst, Robert T. Pappalardo, Jaime A. Cordova, Sona Hosseini, J. L. Noviello, Erika Kohler, Hilairy E. Hartnett, Samuel M. Howell, and Noam R. Izenberg

Subjects
White (horse), Action (philosophy), Scale (ratio), Coronavirus disease 2019 (COVID-19), Meteorology, Environmental science, Blank
Published
2021

43. New Frontiers-class Uranus Orbiter: Exploring the feasibility of achieving multidisciplinary science with a mid-scale mission

Author

Kate Craft, Roland M. B. Young, Paolo Tortora, Ravit Helled, Jonathan J. Fortney, Robert Ebert, Wes Patterson, S. Luszcz-Cook, Alice Lucchetti, Carol Paty, C. M. Jackman, Alessandro Mura, Alan Stern, Alice Cocoros, Ian J. Cohen, Chloe B. Beddingfield, Katrin Stephan, Jesper Gjerloev, Lynnae C. Quick, Catherine Elder, Robert A. Dillman, Drew Turner, Peter Wurz, Matina Gkioulidou, Shawn Brueshaber, Chris Paranicas, Kunio M. Sayanagi, Sasha Ukhorskiy, Sarah E. Moran, R. Nikoukar, Kirby Runyon, Michael H. Wong, Todd Smith, Carolyn M. Ernst, Maurizio Pajola, Matthew M. Hedman, Gianrico Filacchione, Yasumasa Kasaba, Marzia Parisi, Leigh N. Fletcher, Chuanfei Dong, Caitlin Ahrens, Gina A. DiBraccio, Shawn Brooks, Robert Chancia, Michael P. Lucas, Leonardo Regoli, Imke de Pater, Alena Probst, Peter Kollmann, Athena Coustenis, James H. Roberts, Daniel J. Gershman, Lauren Jozwiak, Soumyo Dutta, Linda Spilker, Elizabeth P. Turtle, Sebastien Rodriguez, Yongliang Zhang, Gangkai Poh, George Clark, Tibor S. Balint, Ingrid Daubar, Kathleen Mandt, Adam Masters, Richard Holme, Devanshu Jha, Go Murakami, Noemi Pinilla-Alonso, Sarah K. Vines, Olivier Mousis, Krista M. Soderlund, Athul Pradeepkumar Girija, Ronald J. Vervack, Corey J. Cochrane, Xin Cao, Emma J. Bunce, Shannon MacKenzie, George Hospodarsky, Sébastien Charnoz, Elena Adams, Kimberly Moore, Erin Leonard, Heather Meyer, Rebecca A. Harbison, Abigail Rymer, Sabine Stanley, Barry Mauk, and Richard Cartwright

Subjects
Class (computer programming), Orbiter, Scale (ratio), Multidisciplinary approach, Computer science, law, Systems engineering, Uranus, law.invention
Published
2021

44. Mercury Lander: A New-Frontiers-Class Planetary Mission Concept Design

Author

Jack Ercol, Jackson Shannon, Sanae Kubota, Gabe Rogers, Deva Ponnusamy, Justin A. Atchison, Stewart Bushman, Nancy L. Chabot, Derick Fuller, Benjamin Villac, Daniel Gallagher, Rachel L. Klima, Allan Holtzman, and Carolyn M. Ernst

Subjects
010504 meteorology & atmospheric sciences, Ion thruster, Spacecraft, business.industry, Cruise, Propulsion, 01 natural sciences, Space exploration, Planet, 0103 physical sciences, Environmental science, Terrestrial planet, Aerospace engineering, business, Orbit insertion, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences
Abstract

As an end-member of terrestrial planet formation, Mercury holds unique clues about the original distribution of elements in the earliest stages of solar system development and how planets and exoplanets form and evolve in close proximity to their host stars. The importance of in situ measurements via a landed mission to Mercury was recognized by the 2013–2022 Decadal Survey, and again with its selection for a Planetary Mission Concept Study in support of the 2023–2032 Decadal Survey. Mercury is the only inner planet unexplored by a landed spacecraft; landing on Mercury is uniquely challenging due to the large $\Delta\mathrm{V}$ requirements and extreme thermal environment for such a mission. This paper describes the mission concept design that meets those challenges by leveraging recent technology advances including increased launch vehicle performance capability, further development and use of solar electric propulsion (SEP), and Next-Generation radioisotope thermoelectric generator (NextGen RTG) development. These advances enable a New-Frontiers-class mission concept which achieves one full Mercury year (∼88 Earth days) of surface operations with an 11-instrument, high-heritage payload that is delivered to a landing site within Mercury's widely distributed low-reflectance material, and addresses science goals encompassing geochemistry, geophysics, the Mercury space environment, and geology. The mission concept presented here addresses the primary challenges of a Mercury Lander mission with a four-stage design that launches on an expendable Falcon Heavy vehicle. Mass savings are enabled through jettisoning of stages prior to large burns and optimization of propulsion systems for each phase: cruise, orbit, initial descent, and landing. The flight system utilizes an SEP cruise stage to reach Mercury and jettisons this stage prior to the Mercury orbit insertion (MOI) burn. MOI and orbit-lowering maneuvers are executed with a large bipropellant propulsion system on an orbital stage. During the orbital phase, a narrow-angle camera acquires images for final selection of a low-hazard landing zone within the region of interest. The orbital stage is jettisoned just prior to descent. A solid rocket motor (SRM) descent stage executes the braking burn, and final landing is performed following SRM burnout and jettison with the Lander's bipropellant propulsion system and continuous LIDAR operations to support hazard detection. Landing occurs at dusk to meet thermal requirements, permitting ∼30 hours of sunlight for initial observations. The NextGen RTG powered lander continues operations through the Mercury night. Direct-to-Earth (DTE) communication is available for the initial three weeks of landed operations, unavailable for the following six weeks, and resumes for the final month. Thermal conditions exceed lander operating temperatures shortly after sunrise, ending operations. A total of ∼11 GB of data are returned to Earth.

Published
2021

45. The Morphometry of Impact Craters on Bennu

Author

J. A. Seabrook, R. C. Espiritu, P. Michel, H. Nair, Olivier S. Barnouin, Carolyn M. Ernst, Robert Gaskell, Dante S. Lauretta, Mark E. Perry, J. R. Weirich, Michael C. Nolan, James H. Roberts, Hannah C.M. Susorney, David Trang, R. T. Daly, Eric Palmer, E. B. Bierhaus, Kevin J. Walsh, Catherine L. Johnson, Erica Jawin, Michael Daly, Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Lockheed Martin Space, Department of Earth and Space Science and Engineering [York University - Toronto] (ESSE), York University [Toronto], Planetary Science Institute [Tucson] (PSI), University of Bristol [Bristol], University of British Columbia (UBC), Southwest Research Institute [Boulder] (SwRI), Lunar and Planetary Laboratory [Tucson] (LPL), University of Arizona, Smithsonian Institution National Museum of Natural History (NMNH), Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Hawai'i Institute of Geophysics and Planetology, School of Ocean and Earth Science and Technology, and University of Hawai'i [Honolulu] (UH)

Subjects
Geophysics, [SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph], 010504 meteorology & atmospheric sciences, Impact crater, [SDU]Sciences of the Universe [physics], 0103 physical sciences, [SDU.ASTR.EP]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Earth and Planetary Astrophysics [astro-ph.EP], General Earth and Planetary Sciences, 010303 astronomy & astrophysics, 01 natural sciences, Geomorphology, Geology, 0105 earth and related environmental sciences
Abstract

International audience; Bennu is an~500-m-diameter rubble-pile asteroid that is the target of detailed study by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Here we use data from the OSIRIS-REx Laser Altimeter to assess depth-to-diameter ratios (d/D) of 108 impact craters larger than 10 m in diameter. The d/D of craters on Bennu ranges from 0.02 to 0.19. The mean is 0.10 ± 0.03. The smallest craters show the broadest range in d/D, consistent with d/D measurements on other asteroids. A few craters have central mounds, which is interpreted as evidence that a more competent substrate lies a few meters beneath them. The range of d/D narrows as crater size increases, with craters larger than 80 m tending toward smaller d/D. At large scales, increases in target strength with depth, combined with target curvature, may affect crater morphometry.

Published
2020

46. Author Correction: Shape of (101955) Bennu indicative of a rubble pile with internal stiffness

Author

M. Lefevre, Aaron S. Burton, Carina Bennett, J. A. Mapel, Renu Malhotra, Peter Fleming, J. McAdams, N. Mogk, R. L. Ballouz, P. H. Smith, V. Nifo, C. K. Maleszewski, Timothy D. Swindle, E. Dotto, Stephen R. Schwartz, C. May, J. Bayron, D. Patterson, D. Guevel, Ellen S. Howell, Humberto Campins, J. Kissell, E. Brown, J. Wood, E. Muhle, John Robert Brucato, J. Small, B. Miller, Oleksiy Golubov, R. Pennington, K. Harshman, J. Nelson, Catherine Elder, M. McGee, R. Burns, J. Contreras, S. Hull, D. Kubitschek, D. Noss, Andrew J. Liounis, J. Backer, B. May, G. Fitzgibbon, J. Donaldson, D. Worden, Bashar Rizk, R. Witherspoon, Catherine L. Johnson, Erica Jawin, G. Shaw, A. Aqueche, Dolores H. Hill, D. Folta, S. Ferrone, M. Lujan, Giovanni Poggiali, B. G. Williams, S. Selznick, Melissa A. Morris, K. Rios, Sara S. Russell, D. Lambert, J. Hong, Jeffrey B. Plescia, H. Bloomenthal, D. Drinnon, Olivier S. Barnouin, Derek S. Nelson, Amanda E. Toland, Michael C. Moreau, J. A. Seabrook, K. Dill, A. Mirfakhrai, K. Hyde, J. D. P. Deshapriya, Hannah Kaplan, Timothy P. McElrath, Juliette I. Brodbeck, N. Ramos, S. Stewart, James B. Garvin, Sei-ichiro Watanabe, M. Arvizu-Jakubicki, Jason P. Dworkin, Matthew A. Siegler, Collin Lewin, Masatoshi Hirabayashi, L. Bloomquist, S. Gardner, Keiko Nakamura-Messenger, A. H. Nair, M. Schmitzer, P. Haas, Julie Bellerose, Dolan E. Highsmith, L. Koelbel, C. C. Lorentson, J. Zareski, E. Queen, S. R. Chesley, Philip A. Bland, A. Cheuvront, V. E. Hamilton, Ronald G. Mink, N. Mastrodemos, H. C. Connolly, K. Bellamy, M. Killgore, A. Gardner, Y. Takahashi, M. Lambert, R. C. Espiritu, Z. Zeszut, E. T. Morton, Kevin J. Walsh, Timothy D. Glotch, M. Skeen, Brian Kennedy, Matthew R.M. Izawa, G. Neumann, F. Teti, D. Doerres, A. Hasten, F. Ciceri, D. Howell, A. Deguzman, J. Nagy, D. Vaughan, H. Ma, C. Lantz, D. N. Brack, David K. Hammond, Erwan Mazarico, Leilah K. McCarthy, L. Rhoads, Kathleen L. Craft, C. Welch, Jay W. McMahon, C. L. Parish, D. C. Reuter, M. Giuntini, N. Castro, Clive Dickinson, J. Kreiner, K. Kingsbury, S. Dickenshied, Joseph A. Nuth, Alan R. Hildebrand, Erik Asphaug, H. Ido, Eric M. Sahr, A. Harbison, Arlin E. Bartels, T. Forrester, D. Eckart, R. Bandrowski, Michael K. Barker, Robert Gaskell, J. Wendel, S. Freund, Marc Bernacki, Ryan S. Park, A. Taylor, E. B. Bierhaus, S. Millington-Veloza, J. Stromberg, L. B. Breitenfeld, K. Stakkestad, D. Ellis, Timothy J. McCoy, M. Susak, Richard G. Cosentino, C. Manzoni, Hisayoshi Yurimoto, C. Drouet d'Aubigny, A. Bjurstrom, Masako Yoshikawa, S. Francis, J. Peachey, J. Geeraert, K. Marchese, O. Billett, M. Rascon, F. Jaen, B. Diallo, Martin Miner, Kris J. Becker, E. Mazzotta Epifani, Florian Thuillet, A. Knight, James H. Roberts, Pasquale Tricarico, Edward A. Cloutis, T. Fisher, Dale Stanbridge, A. Colpo, Osiris-Rex Team, S. Gonzales, Q. Tran, M. K. Crombie, John Marshall, N. Bojorquez-Murphy, David Vokrouhlický, Allen W. Lunsford, H. Bowles, K. L. Edmundson, R. A. Masterson, Peter G. Antreasian, N. Gorius, Benjamin Rozitis, D. Pino Muñoz, S. Carlson-Kelly, C. Thayer, J. Elsila Cook, B. C. Clark, N. Piacentine, José C. Aponte, M. Al Asad, M. A. Barucci, D. Blum, P. Falkenstern, Neil Bowles, Matthew Chojnacki, J. M. Leonard, J. Daly, K. Yetter, M. R. Fisher, Jeffrey N. Grossman, A. Boggs, N. Jayakody, Cristina A. Thomas, C.M. Ernst, Namrah Habib, J. N. Kidd, R. J. Steele, Andrew B. Calloway, Andrew Ryan, Kimberly T. Tait, Paul O. Hayne, J. Y. Li, K. L. Berry, William V. Boynton, Yanga R. Fernandez, D. A. Lorenz, M. Wasser, Daniel J. Scheeres, K. Fortney, A. Scroggins, B. Allen, B. Sutter, T. Ferro, Jonathan Joseph, Derek C. Richardson, D. Hoak, Brian Carcich, W. Chang, P. Wren, C. Boyles, Kaj E. Williams, B. Marty, J. Liang, J. Hoffman, A. Harch, Daniel R. Wibben, Jamie Molaro, S. Rieger, R. Enos, C. W. Hergenrother, Stephen R. Sutton, J. Grindlay, E. J. Lessac-Chenen, E. Huettner, C. Norman, P. Sherman, L. Swanson, M. Coltrin, S. Van wal, B. Buck, A. Fisher, Kevin Righter, Brian Rush, David D. Rowlands, Lauren McGraw, A. Levine, K. Drozd, D. Gaudreau, A. Nguyen, S. Sides, M. Chodas, R. Dubisher, B. Ashman, Michael Caplinger, Amy Simon, W. Moore, S. S. Balram-Knutson, R. Carpenter, S. Fornasier, Shogo Tachibana, Russell Turner, Ian A. Franchi, Trevor Ireland, Chloe B. Beddingfield, D. F. Everett, M. Corvin, Lindsay P. Keller, Tammy L. Becker, S. Carter, J. L. Rizos Garcia, Mark E. Perry, E. Keates, Michael C. Nolan, P. Vasudeva, C. Fellows, K. Herzog, Mark A. Jenkins, J. R. Weirich, J. Swenson, D. R. Golish, Davide Farnocchia, Lydia C. Philpott, Rebecca R. Ghent, Hannah C.M. Susorney, S. W. Squyres, Pedro Hasselmann, J. Hill, Thomas J. Zega, B. Key, Marco Delbo, A. S. French, P. Sánchez, A. Hilbert, J. Y. Pelgrift, R. P. Binzel, L. McNamara, Vishnu Reddy, Michael Daly, Scott Messenger, Daniella DellaGiustina, Maurizio Pajola, Charles Brunet, Joshua L. Bandfield, J. Padilla, A. Janakus, M. Moreau, R. Garcia, R. A. Chicoine, P. Michel, P. Kaotira, K. S. Johnson, J. Forelli, G. Miller, K. Martin, I. Galinsky, S. Desjardins, Naru Hirata, Christine Hartzell, M. L. Jones, S. Hooven, D. Velez, R. Munoz, Carolyn M. Ernst, C. Emr, N. Martinez-Vlasoff, S. Bendall, R. Zellar, E. Church, Theodore Kareta, T. Warren, P. Wolff, V. Morrison, C. Bryan, S. Bhaskaran, N. Jones, D. Hauf, Jeremy Bauman, R. T. Daly, R. Olds, M. M. Westermann, D. K. Hamara, E. Audi, G. Johnston, Eric Palmer, Courtney Mario, Daniel P. Glavin, T. Haltigin, J. Cutts, Javier Licandro, Xiao-Duan Zou, H. L. Roper, Gregory A. Neumann, William M. Owen, S. Sugita, Y. H. Tang, Kevin Burke, H. L. Enos, D. Gallagher, William F. Bottke, K. Getzandanner, Philip R. Christensen, C. W. V. Wolner, K. Fleshman, D. Poland, J. P. Emery, M.M. Riehl, D. Fennell, D. Sallitt, A. D. Rogers, M. Fitzgibbon, John H. Jones, S. Mullen, S. Salazar, S. Oliver, A. T. Polit, J. Cerna, A. Praet, Mark E. Holdridge, E. M. Ibrahim, Coralie D. Adam, J. de León, Christopher J. Miller, M. Ryle, J. Lyzhoft, M. Loveridge, C. Hoekenga, Brent J. Bos, S. Anwar, K. Chaffin, Devin L. Schrader, B. Lovelace, Romy D. Hanna, C. D. Adam, G. L. Mehall, K. L. Donaldson Hanna, F. Merlin, B. Wright, Guy Libourel, L. F. Lim, N. Shultz, Dante S. Lauretta, K. Hanley, Beth E. Clark, L. Le Corre, K. Thomas-Keprta, Moses Milazzo, W. Hagee, B. Page, M. Fisher, E. McDonough, D. Trang, S. Clemett, A. Rubi, A. Ingegneri, Scott A. Sandford, D. Dean, J. Freemantle, Michael D. Smith, Christopher W. Haberle, L. Nguyen, M. Fulchignoni, Laboratoire d'études spatiales et d'instrumentation en astrophysique (LESIA (UMR_8109)), Institut national des sciences de l'Univers (INSU - CNRS)-Observatoire de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL), Centre de Mise en Forme des Matériaux (CEMEF), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], 010504 meteorology & atmospheric sciences, Rubble, Stiffness, engineering.material, 010502 geochemistry & geophysics, 01 natural sciences, [SDU]Sciences of the Universe [physics], engineering, medicine, General Earth and Planetary Sciences, Geotechnical engineering, medicine.symptom, Pile, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], Geology, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences
Abstract

International audience

Published
2020

47. Morphometry and temperature of small sub-10 km craters at Mercury’s northern pole: Implications for source and stability of water ice

Author

Hannah C.M. Susorney, Nancy L. Chabot, and Carolyn M. Ernst

Subjects
Impact crater, chemistry, Geochemistry, chemistry.chemical_element, Water ice, Geology, Mercury (element)
Abstract

Mercury’s polar regions host deposits of radar-bright material in regions of permanent shadow, commonly the interior of impact craters, and the deposits are hypothesised to be water ice (i.e., Chabot et al., 2018). Thermal modelling, prior to the arrival of the MESSENGER mission, found that water ice is not thermally stable in craters smaller than 10 km, assuming the craters had a depth-to-diameter ratio of 0.2 (Vasavada et al., 1999). Studies of the distribution of radar-bright deposits have identified deposits in craters under 10 km (Deutsch, et al., 2016). In this study, we used the high-resolution north polar topography from the MESSENGER mission to evaluate the morphometry and temperatures of craters with diameters of 5-10 km to explore if these craters could host stable water ice on geologic timescales. We measured the depth and diameter of 201 5-10 km in diameter craters between 75-85° N. MLA tracks that bisected the crater were used to measure the depth and diameter of 99 craters, spanning all longitudes of this north polar region. Thermal models for the north polar region of Mercury use the gridded MLA topography sampled at 1 km resolution (Paige et al., 2013; Chabot et al., 2018), so it was important to ensure the gridded topography accurately captured the craters’ shapes before using the results of these thermal models for these small craters, Comparisons between the MLA track profiles and the profiles taken through the gridded MLA product showed consistent depth to diameter profiles in both datasets, substantiating the use of the gridded MLA product to be used to determine depth and diameter values for these craters and the thermal models for these craters to be used to explore the stability of water ice in these craters. The average depth-to-diameter ratio of the 201 craters is 0.15, 25% lower than the estimate used in pre-MESSENGER thermal study (Vasavada et al., 1999). Thermal measurements of the 156 craters show that many of them have average temperatures below 110 K, meaning that they have thermal conditions that would allow water ice to be stable on geologic timescales under a thin layer of insulating material. Only three craters had small, single-pixel regions with maximum temperatures under 110 K, suggesting that water ice is not stable on the surface in the majority of small craters, except for isolated regions or below the 1-km scale of the thermal model. These results show that water ice would be stable in simple, sub-10 km diameter craters on Mercury and that the presence of radar-bright deposits in these craters is not a constraint on the age of radar-bright deposits. However, our mapping results do show a clear correlation with radar-bright signatures and longitude. In particular, around 60°E longitude, we observe a higher percentage of radar-bright craters. One of Mercury’s two cold poles is nearby at 90°E, but a large complex crater, Prokofiev-112 km in diameter, is also located at 64°E and many of the craters that are radar-bright appear to be secondaries of Prokofiev. Possible explanations for this longitude distribution are being actively investigated, including association with Prokofiev, cold-pole thermal conditions, effects of radar visibility, and the potential for uneven water ice distribution in the small craters near Mercury’s north pole.

Published
2020

48. Surface densities and boulders size-frequency distribution on binary asteroid (65803) Didymos- Dimorphos

Author

Maurizio Pajola, Alice Lucchetti, Stavro Ivanovski, Giovanni Poggiali, Simone Ieva, Davide Perna, Elisabetta Dotto, Vincenzo Della Corte, Gabriele Cremonese, Elena Mazzotta Epifani, Marilena Amoroso, Simone Pirrotta, Andrew F. Cheng, Nancy L Chabot, Andrew Rivkin, Olivier S Barnouin, Carolyn M Ernst, R. Terik Daly, Masatoshi Hirabayashi, Erik I Asphaug, Stephen R Schwartz, Josep Trigo-Rodríguez, Eugene Fahnestock, Ivano Bertini, John Robert Brucato, Andrea Capannolo, Biagio Cotugno, Valerio Di Tana, Igor Gai, Gabriele Impresario, Michelle Lavagna, Andrea Meneghin, Federico Miglioretti, Dario Modenini, Pasquale Palumbo, Alessandro Rossi, Emanuele Simioni, Simone Simonetti, Paolo Tortora, Marco Zannoni, Giovanni Zannotti, and Angelo Zinzi

Subjects
Astrodynamics, Asteroid impact risk, LICIACube, Asteroid ejecta dynamics
Abstract

In Autumn 2022, the NASA Double Asteroid Redirection Test Mission (DART) will impact the surface of asteroid Dimorphos, a ~165 m body orbiting around asteroid (65803) Didymos, with the main aim to demonstrate the kinetic impactor technique for Planetary Defense. During the last minutes of the mission, the DRACO scienti c camera onboard DART will image the surface of both the primary and the secondary asteroids at different spatial scales, allowing the detection of boulders larger than 0.6-1.5 m on the impacted side of Dimorphos and larger than 11-21 m on Didymos. To complement such observations, the ASI "Light Italian Cubesat for Imaging of Asteroids" (LICIACube) will be released from DART ten days before the impact and will be then autonomously guided through a yby with closest approach distance of 55 km from Dimorphos. Through the LEIA (LICIACube Explorer Imaging for Asteroid) narrow angle camera, it will be possible to safely witness the DART redirection test in situ, while its crater and the ejecta and plume are being formed. At closest approach LEIA will image Dimorphos at ~2 m/px: we will therefore be able to identify all boulders larger than 4-7 m located on the imaged side of the asteroid. The analysis of the boulder surface densities and size frequency distributions (SFD) on Didymos and Dimorphos will be important to understand the processes that originated them (impact cratering versus parent body disruption). In addition, we will compare the SFD derived on the binary asteroid with those obtained on other S-type or carbonaceous minor bodies, highlighting the similarities and differences. In this work, the results of the boulder SFD expected from both LICIACube and DART images are presented. Acknowledgments: This research was supported by the Italian Space Agency (ASI) within the LICIACube project (ASI-INAF agreement AC n. 2019-31-HH.0).

Published
2020

49. AIDA DART asteroid deflection test: Planetary defense and science objectives

Author

Eugene G. Fahnestock, Olivier S. Barnouin, Lance A. M. Benner, Cristina A. Thomas, Justin A. Atchison, Emma S.G. Rainey, Carolyn M. Ernst, Petr Pravec, Nancy L. Chabot, Andrew S. Rivkin, Angela Stickle, A. F. Cheng, Michael Kueppers, Derek C. Richardson, Patrick Michel, Joseph Louis LAGRANGE (LAGRANGE), Université Côte d'Azur (UCA)-Université Nice Sophia Antipolis (... - 2019) (UNS), COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Observatoire de la Côte d'Azur, COMUE Université Côte d'Azur (2015-2019) (COMUE UCA)-Université Côte d'Azur (UCA)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Johns Hopkins University Applied Physics Laboratory [Laurel, MD] (APL), Operations Department (ESAC), European Space Astronomy Centre (ESAC), European Space Agency (ESA)-European Space Agency (ESA), Ondřejov Observatory of the Prague Astronomical Institute, and Czech Academy of Sciences [Prague] (CAS)

Subjects
Orbital speed, 010504 meteorology & atmospheric sciences, 01 natural sciences, law.invention, Telescope, Impact crater, Deflection (engineering), law, 0103 physical sciences, Aerospace engineering, 010303 astronomy & astrophysics, ComputingMilieux_MISCELLANEOUS, 0105 earth and related environmental sciences, computer.programming_language, [PHYS]Physics [physics], Dart, business.industry, Rendezvous, Astronomy and Astrophysics, Orbital period, Space and Planetary Science, Asteroid, Environmental science, [PHYS.ASTR]Physics [physics]/Astrophysics [astro-ph], business, computer
Abstract

The Asteroid Impact & Deflection Assessment (AIDA) mission is an international cooperation between NASA and ESA. NASA plans to provide the Double Asteroid Redirection Test (DART) mission which will perform a kinetic impactor experiment to demonstrate asteroid impact hazard mitigation. ESA proposes to provide the Hera mission which will rendezvous with the target to monitor the deflection, perform detailed characterizations, and measure the DART impact outcomes and momentum transfer efficiency. The primary goals of AIDA are (i) to demonstrate the kinetic impact technique on a potentially hazardous near-Earth asteroid and (ii) to measure and characterize the deflection caused by the impact. The AIDA target will be the binary asteroid (65803) Didymos, which is of spectral type Sq, with the deflection experiment to occur in October, 2022. The DART impact on the secondary member of the binary at ∼6 km/s changes the orbital speed and the binary orbit period, which can be measured by Earth-based observatories with telescope apertures as small as 1 m. The DART impact will in addition alter the orbital and rotational states of the Didymos binary, leading to excitation of eccentricity and libration that, if measured by Hera, can constrain internal structure of the target asteroid. Measurements of the DART crater diameter and morphology can constrain target properties like cohesion and porosity based on numerical simulations of the DART impact.

Published
2018

50. Revolutionizing Our Understanding of the Solar System via Sample Return from Mercury

Author

Francis M. McCubbin, Kathleen E. Vander Kaaden, Nancy L. Chabot, Catherine L. Johnson, Michelle S. Thompson, Carolyn M. Ernst, and Paul K. Byrne

Subjects
Solar System, 010504 meteorology & atmospheric sciences, Spacecraft, business.industry, chemistry.chemical_element, Astronomy and Astrophysics, 01 natural sciences, Space weathering, Astrobiology, Mercury (element), Planetary science, chemistry, 13. Climate action, Space and Planetary Science, Planet, 0103 physical sciences, Terrestrial planet, Environmental science, business, 010303 astronomy & astrophysics, 0105 earth and related environmental sciences, Exosphere
Abstract

Data from Mariner 10, MESSENGER, and ground-based telescopic observations have facilitated great advancements towards understanding the geochemistry, geology, internal structure, exosphere, and magnetosphere of Mercury. However, there are critical science questions that can be only addressed via examination of a sample in Earth-based laboratories, where numerous highly sensitive analytical measurements are possible. Collecting a sample from the surface of Mercury and bringing it to Earth for in-depth analysis would allow for transformative Solar System science to be conducted, examining aspects of our Solar System such as the evolution of the protoplanetary disk, space weathering on airless bodies, the geochemical behavior of elements at extreme conditions, and the origin and distribution of volatiles across the terrestrial planets. Furthermore, our knowledge of Mercury’s differentiation and geochemical processes, chronology and geologic evolution, tectonism and geomechanical properties, and past and ongoing magnetism would be greatly advanced via analysis of a sample from Mercury. Although there are ample challenges and knowledge gaps associated with sample return from Mercury in terms of both spacecraft requirements and material requirements for curatorial facilities, a sample from the planet would be an invaluable scientific resource for generations to come, enabling the most sophisticated measurements to be brought to bear for decades and helping to truly unlock the mysteries of our Solar System.

Published
2019

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