41 results on '"Connolly, H. C., Jr"'
Search Results
2. A Unique Amphibole- and Magnetite-Rich Carbonaceous Chondrite from Almahata Sitta
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Goodrich, C. A, Hamilton, V. E, Zolensky, M, Kita, N. T, Fioretti, A. M, Kohl, I, Young, E, Treiman, A. H, Connolly, H. C., Jr, Filiberto, J, Shaddad, M. H, and Jenniskens, P
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Space Sciences (General) - Abstract
Almahata Sitta (AhS) 202 from the UoK collection represents a clast from the polymict breccia asteroid 2008 TC3. AhS 202 was recognized as a unique carbonaceous chondrite (CC) with a high magnetite content. Here we report that it also contains a significant amount of amphibole, a mineral that is very rare in chondrites and has not previously been reported in significant abundance in a CC. We present new petrographic, oxygen isotope, and micro-FTIR data. We discuss petrogenesis and possible relationships to known CC.
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- 2020
3. Properties of Rubble-Pile Asteroid (101955) Bennu from OSIRIS-REx Imaging and Thermal Analysis
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DellaGiustina, D. N, Emery, J. P, Golish, D. R, Rozitis, B, Bennett, C. A, Burke, K. N, Ballouz, R.-L, Becker, K. J, Christensen, P. R, Drouet d’Aubigny, C. Y, Hamilton, V. E, Reuter, D. C, Rizk, B, Simon, A. A, Asphaug, E, Bandfield, J. L, Barnouin, O. S, Barucci, M. A, Binzel, R. P, Bottke, W. F, Bowles, N. E, Campins, H, Clark, B. C, Clark, B. E, Connolly, H. C., Jr, Daly, M. G, de Leon, J, Delbo, M, Deshapriya, J. D. P, Fornasier, S, Hergenrother, C. W, Jawin, E. R, Howell, E. S, Kaplan, H. H, Kareta, T. R, Corre, L. Le, Li, J.-Y, Licandro, J, Lim, L. F, Michel, P, Molaro, J, Nolan, M. C, Popescu, M, Rizos Garcia, J. L, Ryan, A, Schwartz, S. R, Shultz, N, Siegler, M. A, Smith, P. H, Tatsumi, E, Thomas, C. A, Walsh, K. J, Wolner, C. W. V, Zou, X.-D, Lauretta, D. S, Highsmith, D. E, Small, J, Vokrouhlick, D, Brown, E, Hanna, K. L. Donaldson, Warren, T, Brunet, C, Chicoine, R. A, Desjardins, S, Gaudreau, D, Haltigin, T, Millington-Veloza, S, Rubi, A, Aponte, J, Gorius, N, Lunsford, A, Allen, B, Grindlay, J, Guevel, D, Hoak, D, Hong, J, Schrader, D. L, Bayron, J, Golubov, O, Sánchez, P, Stromberg, J, Hirabayashi, M, Hartzell, C. M, Oliver, S, Rascon, M, Harch, A, Joseph, J, Squyres, S, Richardson, D, McGraw, L, Ghent, R, Al Asad, M. M, Johnson, C. L, Philpott, L, Susorney, H. C. M, Cloutis, E. A, Hanna, R. D, Ciceri, F, Hildebrand, A. R, Ibrahim, E.-M, Breitenfeld, L, Glotch, T, Rogers, A. D, Ferrone, S, Fernandez, Y, Chang, W, Cheuvront, A, Trang, D, Tachibana, S, Yurimoto, H, Brucato, J. R, Poggiali, G, Pajola, M, Dotto, E, Mazzotta Epifani, E, Crombie, M. K, Lantz, C, Izawa, M. R. M, Leon, J. de, Clemett, S, Thomas-Keprta, K, Van wal, S, Yoshikawa, M, Bellerose, J, Bhaskaran, S, Boyles, C, Chesley, S. R, Elder, C. M, Farnocchia, D, Harbison, A, Kennedy, B, Knight, A, Martinez-Vlasoff, N, Mastrodemos, N, McElrath, T, Owen, W, Park, R, Rush, B, Swanson, L, Takahashi, Y, Velez, D, Yetter, K, Thayer, C, Adam, C, Antreasian, P, Bauman, J, Bryan, C, Carcich, B, Corvin, M, Geeraert, J, Hoffman, J, Leonard, J. M, Lessac-Chenen, E, Levine, A, McAdams, J, McCarthy, L, Nelson, D, Page, B, Pelgrift, B, Sahr, E, Stakkestad, K, Stanbridge, D, Wibben, D, Williams, B, Williams, K, Wolff, P, Hayne, P, Kubitschek, D, Fulchignoni, M, Hasselmann, P, Merlin, F, Praet, A, Bierhaus, E. B, Billett, O, Boggs, A, Buck, B, Carlson-Kelly, S, Cerna, J, Chaffin, K, Church, E, Coltrin, M, Daly, J, Deguzman, A, Dubisher, R, Eckart, D, Ellis, D, Falkenstern, P, Fisher, A, Fisher, M. E, Fleming, P, Fortney, K, Francis, S, Freund, S, Gonzales, S, Haas, P, Hasten, A, Hauf, D, Hilbert, A, Howell, D, Jaen, F, Jayakody, N, Jenkins, M, Johnson, K, Lefevre, M, Ma, H, Mario, C, Martin, K, May, C, McGee, M, Miller, B, Miller, C, Miller, G, Mirfakhrai, A, Muhl, E, Norman, C, Olds, R, Parish, C, Ryle, M, Schmitzer, M, Sherman, P, Skeen, M, Susak, M, Sutter, B, Tran, Q, Welch, C, Witherspoon, R, Wood, J, Zareski, J, Arvizu-Jakubicki, M, Audi, E, Bandrowski, R, Becker, T. L, Bendall, S, Bloomenthal, H, Blum, D, Boynton, W. V, Brodbeck, J, Chojnacki, M, Colpo, A, Contreras, J, Cutts, J, Dean, D, Diallo, B, Drinnon, D, Drozd, K, Enos, H. L, Enos, R, Fellows, C, Ferro, T, Fisher, M. R, Fitzgibbon, G, Fitzgibbon, M, Forelli, J, Forrester, T, Galinsky, I, Garcia, R, Gardner, A, Habib, N, Hamara, D, Hammond, D, Hanley, K, Harshman, K, Herzog, K, Hill, D, Hoekenga, C, Hooven, S, Huettner, E, Janakus, A, Jones, J, Kidd, J, Kingsbury, K, Balram-Knutson, S. S, Koelbel, L, Kreiner, J, Lambert, D, Lewin, C, Lovelace, B, Loveridge, M, Lujan, M, Maleszewski, C. K, Malhotra, R, Marchese, K, McDonough, E, Mogk, N, Morrison, V, Morton, E, Munoz, R, Nelson, J, Padilla, J, Pennington, R, Polit, A, Ramos, N, Reddy, V, Riehl, M, Roper, H. L, Salazar, S, Selznick, S, Stewart, S, Sutton, S, Swindle, T, Tang, Y. H, Westermann, M, Worden, D, Zega, T, Zeszut, Z, Bjurstrom, A, Bloomquist, L, Dickinson, C, Keates, E, Liang, J, Nifo, V, Taylor, A, Teti, F, Caplinger, M, Bowles, H, Carter, S, Dickenshied, S, Doerres, D, Fisher, T, Hagee, W, Hill, J, Miner, M, Noss, D, Piacentine, N, Smith, M, Toland, A, Wren, P, Bernacki, M, Pino Munoz, D, Watanabe, S.-I, Sandford, S. A, Aqueche, A, Ashman, B, Barker, M, Bartels, A, Berry, K, Bos, B, Burns, R, Calloway, A, Carpenter, R, Castro, N, Cosentino, R, Donaldson, J, Dworkin, J. P, Cook, J. Elsila, Emr, C, Everett, D, Fennell, D, Fleshman, K, Folta, D, Gallagher, D, Garvin, J, Getzandanner, K, Glavin, D, Hull, S, Hyde, K, Ido, H, Ingegneri, A, Jones, N, Kaotira, P, Liounis, A, Lorentson, C, Lorenz, D, Lyzhoft, J, Mazarico, E. M, Mink, R, Moore, W, Moreau, M, Mullen, S, Nagy, J, Neumann, G, Nuth, J, Poland, D, Rhoads, L, Rieger, S, Rowlands, D, Sallitt, D, Scroggins, A, Shaw, G, Swenson, J, Vasudeva, P, Wasser, M, Zellar, R, Grossman, J, Johnston, G, Morris, M, Wendel, J, Burton, A, Keller, L. P, McNamara, L, Messenger, S, Nakamura-Messenger, K, Nguyen, A, Righter, K, Queen, E, Bellamy, K, Dill, K, Gardner, S, Giuntini, M, Key, B, Kissell, J, Patterson, D, Vaughan, D, Wright, B, Gaskell, R. W, Le Corre, L, Molaro, J. L, Palmer, E. E, Tricarico, P, Weirich, J. R, Ireland, T, Tait, K, Bland, P, Anwar, S, Bojorquez-Murphy, N, Haberle, C. W, Mehall, G, Rios, K, Franchi, I, Beddingfield, C. B, Marshall, J, Brack, D. N, French, A. S, McMahon, J. W, Scheeres, D. J, McCoy, T. J, Russell, S, Killgore, M, Chodas, M, Lambert, M, Masterson, R. A, Freemantle, J, Seabrook, J. A, Craft, K, Daly, R. T, Ernst, C, Espiritu, R. C, Holdridge, M, Jones, M, Nair, A. H, Nguyen, L, Peachey, J, Perry, M. E, Plescia, J, Roberts, J. H, Steele, R, Turner, R, Backer, J, Edmundson, K, Mapel, J, Milazzo, M, Sides, S, Manzoni, C, May, B, Libourel, G, Thuillet, F, and Marty, B
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Lunar And Planetary Science And Exploration - Abstract
Establishing the abundance and physical properties of regolith and boulders on asteroids is crucial for understanding the formation and degradation mechanisms at work on their surfaces. Using images and thermal data from NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft, we show that asteroid (101955) Bennu's surface is globally rough, dense with boulders, and low in albedo. The number of boulders is surprising given Bennu's moderate thermal inertia, suggesting that simple models linking thermal inertia to particle size do not adequately capture the complexity relating these properties. At the same time, we find evidence for a wide range of particle sizes with distinct albedo characteristics. Our findings imply that ages of Bennu's surface particles span from the disruption of the asteroid's parent body (boulders) to recent in situ production (micrometre-scale particles).
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- 2019
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4. OSIRIS-REx Contamination Control Strategy and Implementation
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Dworkin, J. P, Adelman, L. A, Ajluni, T. M, Andronikov, A. V, Aponte, J. S, Bartels, A. E, Beshore, E, Bierhaus, E. B, Brucato, J. R, Bryan, B. H, Burton, A. S, Callahan, M. P, Castro-Wallace, S. L, Clark, B. C, Clemett, S. J, Connolly, H. C., Jr, Cutlip, W. E, Daly, S. M, Elliott, V. E, Elsila, J. E, Enos, H. L, Everett, D. F, Franchi, I. A, Glavin, D. P, Graham, H. V, Hendershot, J. E, Harris, J. W, Hill, S. L, Hildebrand, A. R, Jayne, G. O, Jenkens, R. W., Jr, Johnson, K. S, Kirsch, J. S, Lauretta, D. S, Lewis, A. S, Loiacono, J. J, Lorentson, C. C, Marshall, J. R, Martin, M. G, Matthias, L. L, McLain, H. L, Messenger, S. R, Mink, R. G, Moore, J. L, Nakamura-Messenger, K, Nuth, J. A., III, Owens, C. V, Parish, C. L, Perkins, B. D, Pryzby, M. S, Reigle, C. A, Righter, K, Rizk, B, Russell, J. F, Sandford, S. A, Schepis, J. P, Songer, J, Sovinski, M. F, Stahl, S. E, Thomas-Keprta, K, Vellinga, J. M, and Walker, M. S
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Lunar And Planetary Science And Exploration - Abstract
OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and less than 180 ng/cm(exp 2) of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.
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- 2017
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5. Spectral Characterization of Analog Samples in Anticipation of OSIRIS-REx's Arrival at Bennu
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Donaldson Hanna, K. L, Schrader, D. L, Bowles, N. E, Clark, B. E, Cloutis, E. A, Connolly, H. C., Jr, Hamilton, V. E, Keller, L. P, Lauretta, D. S, Lim, L. F, and McCoy, T. J
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Astronomy ,Lunar And Planetary Science And Exploration - Abstract
NASA's Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission successfully launched on September 8th, 2016. During its rendezvous with near-Earth asteroid (101955) Bennu beginning in 2018, OSIRIS-REx will characterize the asteroid's physical, mineralogical, and chemical properties in an effort to globally map the properties of Bennu, a primitive carbonaceous asteroid, and choose a sampling location]. In preparation for these observations, analog samples were spectrally characterized across visible, near- and thermal-infrared wavelengths and were used in initial tests on mineral-phase-detection and abundance-determination software algorithms.
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- 2017
6. Lessons Learned from Preparing OSIRIS-REx Spectral Analog Samples for Bennu
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Schrader, D. L, McCoy, T. J, Cody, G. D, King, A. J, Schofield, P. F, Russell, S. S, Connolly, H. C., Jr, Keller, L. P, Donaldson Hanna, K, Bowles, N, Cloutis, E. A, Mann, J. P, Applin, D. M, Lauretta, D. S, Clark, B. E, Hamilton, V. E, and Lim, L
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Lunar And Planetary Science And Exploration - Abstract
NASA's OSIRIS-REx sample return mission launched on September 8th, 2016 to rendezvous with B-type asteroid (101955) Bennu in 2018. Type C and B asteroids have been linked to carbonaceous chondrites because of their similar visible - to - near infrared (VIS-NIR) spectral properties [e.g., 1,2]. The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) and the Thermal Emission Spectrometer (OTES) will make spectroscopic observations of Bennu during the encounter. Constraining the presence or absence of hydrous minerals (e.g., Ca-carbonate, phyllosilicates) and organic molecules will be key to characterizing Bennu [3] prior to sample site selection. The goal of this study was to develop a suite of analog and meteorite samples and obtain their spectral properties over the wavelength ranges of OVIRS (0.4- 4.3 micrometer) and OTES (5.0-50 micrometer). These spectral data were used to validate the mission science-data processing system. We discuss the reasoning behind the study and share lessons learned.
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- 2017
7. Chondrules and Opaque Phases in Unequilibrated R Chondrites: A Comprehensive Assessment of Their Formation
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Miller, K. E, Lauretta, D. S, Connolly, H. C., Jr, Berger, E. L, and Domanik, K
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Geophysics - Abstract
Equilibrated Rumuruti (R) chondrites record an oxygen fugacity between 0 and 3.5 log units below the fayalite-magnetite-quartz buffer, and a sulfur fugacity (fS2) 2 log units above the iron-troilite buffer. They are more than an order of magnitude more oxidized than the ordinary chondrites [1], and orders of magnitude more sulfidized than solar values. Although the R chondrites have the highest (delta)O-17 value of any meteorites, analyses of unequilibrated R chondrites indicate chondrule formation in an oxygen isotope reservoir similar to that of the ordinary chondrite chondrules. We present the relationship of the R chondrite parent body to pre-accretionary volatiles O and S based on our analyses of unequilibrated R chondrite material in two thin sections from the meteorite Mount Prestrud (PRE) 95404.
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- 2016
8. The OSIRIS-REx Contamination Control and Witness Strategy
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Dworkin, J. P, Adelman, L, Ajluni, T. M, Andronikov, A. V, Ballou, D. M, Bartels, A. E, Beshore, E, Bierhaus, E. B, Boynton, W. V, Brucato, J. R, Callahan, M. P, Benton, B. C, Connolly, H. C., Jr, Enos, H. L, Elsila, J. E, Everett, D. F, Franchi, I. A, Fust, J. S, Glavin, D. P, Hendershot, J. E, Harris, J. W, Hildebrand, A. R, Jayne, G, Jenkins, R. W, Kretsch, W. E, Kuhns, R. M, Lauretta, D. S, Ladewig, J. V, Lorentson, C. C, Marshall, J. R, Matthias, L. L, McLain, H. L, Messenger, S. R, Mink, R. G, Moore, J, Nakamura-Messenger, K, Nuth, J. A, Righter, K, Roher, W. D, Sandford, S. A, Schepis, J. P, Sovinski, M. F, and Walker, M. S
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Lunar And Planetary Science And Exploration ,Life Sciences (General) - Abstract
The OSIRIS-REx mission (Origins, Spectral Interpretation, Resource Identification, and Security Regolith Explorer) is the third NASA New Frontiers mission. It is scheduled for launch in 2016. The primary objective of the mission is to return at least 60 g of "pristine" material from the B-type near- Earth asteroid (101955) Bennu, which is spectrally similar to organic-rich CI or CM meteorites [1]. The study of these samples will advance our understanding of materials available for the origin of life on Earth or elsewhere. The spacecraft will rendezvous with Bennu in 2018 and spend at least a year characterizing the asteroid before executing a maneuver to recover a sample of regolith in the touch-and-go sample acquisition mechanism (TAGSAM). The TAGSAM and sample is stowed in the sample return capsule (SRC) and returned to Earth in 2023.
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- 2015
9. Investigating the Geological History of Asteroid 101955 Bennu Through Remote Sensing and Returned Sample Analyses
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Messenger, S, Connolly, H. C., Jr, Lauretta, D. S, and Bottke, W. F
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Lunar And Planetary Science And Exploration - Abstract
The NASA New Frontiers Mission OSRIS-REx will return surface regolith samples from near-Earth asteroid 101955 Bennu in September 2023. This target is classified as a B-type asteroid and is spectrally similar to CI and CM chondrite meteorites [1]. The returned samples are thus expected to contain primitive ancient Solar System materials that formed in planetary, nebular, interstellar, and circumstellar environments. Laboratory studies of primitive astromaterials have yielded detailed constraints on the origins, properties, and evolutionary histories of a wide range of Solar System bodies. Yet, the parent bodies of meteorites and cosmic dust are generally unknown, genetic and evolutionary relationships among asteroids and comets are unsettled, and links between laboratory and remote observations remain tenuous. The OSIRIS-REx mission will offer the opportunity to coordinate detailed laboratory analyses of asteroidal materials with known and well characterized geological context from which the samples originated. A primary goal of the OSIRIS-REx mission will be to provide detailed constraints on the origin and geological and dynamical history of Bennu through coordinated analytical studies of the returned samples. These microanalytical studies will be placed in geological context through an extensive orbital remote sensing campaign that will characterize the global geological features and chemical diversity of Bennu. The first views of the asteroid surface and of the returned samples will undoubtedly bring remarkable surprises. However, a wealth of laboratory studies of meteorites and spacecraft encounters with primitive bodies provides a useful framework to formulate priority scientific questions and effective analytical approaches well before the samples are returned. Here we summarize our approach to unraveling the geological history of Bennu through returned sample analyses.
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- 2014
10. Strategy for Ranking the Science Value of the Surface of Asteroid 101955 Bennu for Sample Site Selection for Osiris-REx
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Nakamura-Messenger, K, Connolly, H. C., Jr, and Lauretta, D. S
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Astronautics (General) ,Lunar And Planetary Science And Exploration - Abstract
OSRIS-REx is NASA's New Frontiers 3 sample return mission that will return at least 60 g of pristine surface material from near-Earth asteroid 101955 Bennu in September 2023. The scientific value of the sample increases enormously with the amount of knowledge captured about the geological context from which the sample is collected. The OSIRIS-REx spacecraft is highly maneuverable and capable of investigating the surface of Bennu at scales down to the sub-cm. The OSIRIS-REx instruments will characterize the overall surface geology including spectral properties, microtexture, and geochemistry of the regolith at the sampling site in exquisite detail for up to 505 days after encountering Bennu in August 2018. The mission requires at the very minimum one acceptable location on the asteroid where a touch-and-go (TAG) sample collection maneuver can be successfully per-formed. Sample site selection requires that the follow-ing maps be produced: Safety, Deliverability, Sampleability, and finally Science Value. If areas on the surface are designated as safe, navigation can fly to them, and they have ingestible regolith, then the scientific value of one site over another will guide site selection.
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- 2014
11. Chondrule Crystallization Experiments
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Hweins, R. H, Connolly, H. C., Jr, Lofgren, G. E, and Libourel, G
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Lunar And Planetary Science And Exploration - Abstract
Given the great diversity of chondrules, laboratory experiments are invaluable in yielding information on chondrule formation process(es) and for deciphering their initial conditions of formation together with their thermal history. In addition, they provide some critical parameters for astrophysical models of the solar system and of nebular disk evolution in particular (partial pressures, temperature, time, opacity, etc). Most of the experiments simulating chondrules have assumed formation from an aggregate of solid grains, with total pressure of no importance and with virtually no gain or loss of elements from or to the ambient environment. They used pressed pellets attached to wires and suffered from some losses of alkalis and Fe.
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- 2004
12. Locating Stardust-like particles in aerogel using x-ray techniques
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Jurewicz, A. J, Jones, S. M, Tsapin, A, Min, D. T, Connolly, H. C. Jr, and Grahm, G. A
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- 2003
13. Locating Stardust-like particles in aerogel using x-ray techniques
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Grahm, G. A, Connolly, H. C. Jr, Min, D. T, Tsapin, A, Jones, S. M, and Jurewicz, A. J
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UNKNOWN
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- 2003
14. Locating Stardust-like Particles in Aerogel Using X-Ray Techniques
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Jurewicz, A. J. G, Jones, S. M, Tsapin, A, Mih, D. T, Connolly, H. C., Jr, and Graham, G. A
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Instrumentation And Photography - Abstract
Silica aerogel is the material that the spacecraft STARDUST is using to collect interstellar and cometary silicates. Anticipating the return of the samples to earth in January of 2006, MANY individual investigators and, especially, the investigators in NASA's SRLIDAP program are studying means of both in situ analysis of particles, as well as particle extraction. To help individual PI's with extraction of particles from aerogel in their own laboratories, we are exploring the use of standard laboratory x-ray equipment and commercial techniques for precisely locating specific particles in aerogel. We approached the evaluation of commercial x-ray techniques as follows. First, we determined the most appropriate detector for use with aerogel and particulates. Then, we compared and contrasted techniques useful for university laboratories.
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- 2003
15. The Formation of Chondrules: Petrologic Tests of the Shock Wave Model
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Connolly, H. C., Jr and Love, S. G
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Chondrules are mm-sized spheroidal igneous components of chondritic meteorites. They consist of olivine and orthopyroxene set in a glassy mesostasis with varying minor amounts of metals, sulfieds, oxides and carbon phases.
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- 1998
16. Compound chondrules: An experimental investigation
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Connolly, H. C., Jr, Hewins, R. H, Atre, N, and Lofgren, G. E
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Lunar And Planetary Exploration - Abstract
Compound chondrules are considered to be the product of collisions between molten chondrules during chondrule formation Wasson, J. T. et al. (1994) have argued that some compound chondrules are formed when a chondrule with an accretional rim experienced a flash-melting event similar to a chondrule-forming event. We have designed experiments to investigate the formation of compound chondrules by both methods. Experiments were performed on a Deltech vertical muffle tube furnace to form synthetic chondrules to use as accretion rim material. For our experimental conditions, it is clear that compound chondrules can only be made by a collisional event. Our changes maintain their spherical shape and produce distinct boundaries between charges that are similar to natural compound chondrules. Furthermore, collision event(s) between chondrules will cause nucleation if they are molten and undercooled, thus producing chondrule textures. Flash melting chondrules with accretionary rims will not produce compound chondrules but will produce new chondrules with new textures.
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- 1994
17. Constraints placed on the nature of chondrule precursors
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Connolly, H. C., Jr and Hewins, R. H
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Astrophysics - Abstract
The melting conditions and cooling rates experienced by chondrules have been experimentally investigated and reviewed. A discussion of experiments that have studied the nature of chondrule precursors and what constraints these experiments have placed on chondrule precursors is presented. Topics discussed include the following: (1) physical characteristics of starting compositions; (2) chemical characteristics of starting compositions; and (3) constraints on chondrule precursors.
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- 1994
18. Chondrule precursors and cooling paths: The sulfur evidence
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Zanda, B, Yu, Y, Bourot-Denise, M, Hewins, R. H, and Connolly, H. C., Jr
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Astrophysics - Abstract
The behavior of moderately volatile elements (Na and S) is controversial but critical in understanding chondrule precursors and heating processes. Sulfide appeared to be present in most chondrules, but S should have been vaporized during chondrule formation. In fact, S is extensively redistributed in the course of metamorphism, and its abundance at the end of chondrule formation can only be inferred from the least equilibrated chondrites. Our study of 530 chondrules from Renazzo (CR2) and Semarkona (LL3.0) shows partial volatilization of S during chondrule formation and our melting experiments define conditions for total loss or partial retention of S.
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- 1994
19. Flash heating is required to minimize sodium losses from chondrules
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Yu, Y, Hewins, R. H, and Connolly, H. C., Jr
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Astrophysics - Abstract
Chondrules were formed by high-temperature melting events, but do not always show Na depletion compared to CI chondrites, though extensive Na loss has been found in previous isothermal experiments. While Na loss can be prevented by high partial pressure of Na in the nebula, many people favor a flash-heating mechanism to reduce the Na loss from chondrule melts. To examine the validity of the flash-heating hypothesis, we have conducted a series of flash-heating experiments and observed Na loss rate under different conditions. Our results support the flash heating as a plausible heating mechanism to form chondrules.
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- 1994
20. Experimental constraints on models for origins of chondrules: Peak temperatures
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Hewins, R. H and Connolly, H. C., Jr
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Astrophysics - Abstract
Chondrule peak temperature constraints for mathematical models pertaining to chondrule origin are discussed in this article. The peak temperatures experienced by chondrules provide a parameter that may allow discrimination between alternative heating mechanisms. Successful mechanisms must provide just enough energy to reach such temperatures and not overshoot them. In principle, determination of peak temperatures from chondrule textures and experiments that duplicate them should be very easy. However, this approach is complicated by the fact that there are several different experimental paths that reproduce chondrule properties. The key texture depends not only on the peak temperature but also on the heating time and, in the case of totally molten droplets, on interactions with other particles. Addressed here are different types of peak temperature constraints; (1) near-liquidus melting; (2) flash melting; (3) dust seeding; (4) volatile element constraints; and (5) barred olivine chondrules.
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- 1994
21. Allende 3509 HC-2: A Compact Type A-‘F’ Inclusion with a Snake-Like Morphology
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Connolly, H. C., Jr., Beckett, J. R., Huss, G. R., Nagashima, K., Young, E. D., Ziegler, K., Ma, C., and Rossman, George R.
- Abstract
Calcium-, aluminum-rich inclusions (CAIs) are the first rocks to form in the solar system. Some inclusions are igneous and a very few of these (called F inclusions) experienced significant mass dependant fractionation in oxygen [1], and in some cases, other isotopic systems (FUN inclusions). Increasing the number and types of F inclusions will provide additional constraints on CAI formation and their formation environments. We report here on a Compact Type A (CTA) inclusion from Allende with an overall snake-like morphology, is an F inclusion, and initial ^(26)Al/^(27)Al that was canonical.
- Published
- 2011
22. In-situ Discovery of a Cluster of Refractory Grains in an Allende Ferromagnesian Chondrule
- Author
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Ma, C., Beckett, J. R., Rossman, G. R., Connolly, H. C., Jr., Guan, Y., Eiler, J. M., and Hofmann, A. E.
- Abstract
During our nano-mineralogy investigation of the Allende meteorite, we discovered a unique corundum-rich cluster of irregular micrometer-sized refractory grains in a type IA chondrule. The presence of relatively oxidized (rutile) and highly reduced (a new mineral Ti_2O_3, khamrabaevite) phases in the same cluster reflects distinctly different environments prior to incorporation of the cluster into the chondrule. To our knowledge, this is the first occurrence of such a cluster. Investigation of phases that are clearly exotic to the host chondrule and may predate its formation can provide not only important constraints on the materials present when chondrules formed and the enviroments within or outside the Protoplanetary disk, but also on the chondrule formation event. Herein we report our prelimary results on the mineralogy of these grains and the overall petrology of their host chondrule.
- Published
- 2009
23. The Meteoritical Bulletin No. 91, 2007 March
- Author
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Connolly H. C., Jr, Zipfel, J, Folco, Luigi, Smith, C, Jones, R. H., Benedix, G. K., Righter, K., Yamaguchi, A, Chennaoui Aoudjehane, H, and Grossmann, J. N.
- Published
- 2007
24. The Meteoritical Bulletin, No. 89, 2005 September
- Author
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Russell, S. S., Zolensky, M. E., Righter, K, Folco, Luigi, Jones, R, Connolly H. C., Jr, Grady, M. M., and Grossman, J. N.
- Published
- 2005
25. On the Remelting of Type B Calcium-Aluminum-rich Inclusions
- Author
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Connolly, H. C., Jr. and Burnett, D. S.
- Abstract
We have shown [1-3] that the variation in the minor-element concentration of spinels (MgAI_20_4 and their relationship to host silicate chemistry from type B CAIs is a powerful tool in constraining the igneous history of these objects. We conducted electron microprobe studies of the minor-element distributions among spinels from three type Bl CAIs: Allende TS-34, Allende TS-23, and Leoville 3537-2. By maintaining the petrologic context (edge, middle, and center of the inclusion plus their host silicate phase), four populations of spinels are resolvable based on their positive TI to V correlation. Grains from the middle and center areas define trends that are divided into three populations: spinels enclosed by melilite, fassaite, and anorthite. These grains also show important TI, V, and Cr correlations with their host silicate chemistries. The other population resides within the edge area (mainly mantle melilite) and is characterized by the highest V contents with little chemical relationship to their host silicates.
- Published
- 2000
26. Recycling (?): Relict Spinels (?) in Type B Calcium-Aluminum-Rich Inclusions
- Author
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Connolly, H. C., Jr. and Burnett, D. S.
- Abstract
Type B calcium-aluminum-rich inclusions (CAIs) can be thought of as a type of chondrule despite obvious differences in size, composition, and texture. Nevertheless, igneous CAIs likely experienced similar thermal histories. A major constraint on the thermal history of chondrules is that they have been recycled, mainly supported by the presence relict grains. Although well known that igneous CAIs experienced at least two melting events (counting Wark-Lovering rims), the identification of relict grains has been problematic. The best candidate for relict grains within type B CAIs is spinel. Spinel is the liquidus phase with complete melting at approximately l50°C above type B peak melting temperatures (~1400°C). Consequently, relict spinels, either from a previous generation of CAIs or direct nebular condensate spinels, are stable at the inferred maximum heating temperature of type B CAIs. Minor- and trace-element concentrations can be used to distinguish relict grains from those that crystallized from an initially homogeneous liquid.
- Published
- 1998
27. Numerical simulations suggest asteroids (101955) Bennu and (162173) Ryugu are likely second or later generation rubble piles.
- Author
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Walsh KJ, Ballouz RL, Bottke WF, Avdellidou C, Connolly HC Jr, Delbo M, DellaGiustina DN, Jawin ER, McCoy T, Michel P, Morota T, Nolan MC, Schwartz SR, Sugita S, and Lauretta DS
- Abstract
Rubble pile asteroids are widely understood to be composed of reaccumulated debris following a catastrophic collision between asteroids in the main asteroid belt, where each disruption can make a family of new asteroids. Near-Earth asteroids Ryugu and Bennu have been linked to collisional families in the main asteroid belt, but surface age analyses of each asteroid suggest these bodies are substantially younger than their putative families. Here we show, through a coupled collisional and dynamical evolution of members of these families, that neither asteroid was likely to have been created at the same time as the original family breakups, but rather are likely remnants of later disruptions of original family members, making them second, or later, generation remnants. Our model finds about 80% and 60% of asteroids currently being delivered to near-Earth orbits from the respective families of New Polana and Eulalia are second or later generation. These asteroids delivered today in the 0.5-1 km size range have median ages since their last disruption that are substantially younger than the family age, reconciling their measured crater retention ages with membership in these families., (© 2024. The Author(s).)
- Published
- 2024
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28. Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples.
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Nakamura T, Matsumoto M, Amano K, Enokido Y, Zolensky ME, Mikouchi T, Genda H, Tanaka S, Zolotov MY, Kurosawa K, Wakita S, Hyodo R, Nagano H, Nakashima D, Takahashi Y, Fujioka Y, Kikuiri M, Kagawa E, Matsuoka M, Brearley AJ, Tsuchiyama A, Uesugi M, Matsuno J, Kimura Y, Sato M, Milliken RE, Tatsumi E, Sugita S, Hiroi T, Kitazato K, Brownlee D, Joswiak DJ, Takahashi M, Ninomiya K, Takahashi T, Osawa T, Terada K, Brenker FE, Tkalcec BJ, Vincze L, Brunetto R, Aléon-Toppani A, Chan QHS, Roskosz M, Viennet JC, Beck P, Alp EE, Michikami T, Nagaashi Y, Tsuji T, Ino Y, Martinez J, Han J, Dolocan A, Bodnar RJ, Tanaka M, Yoshida H, Sugiyama K, King AJ, Fukushi K, Suga H, Yamashita S, Kawai T, Inoue K, Nakato A, Noguchi T, Vilas F, Hendrix AR, Jaramillo-Correa C, Domingue DL, Dominguez G, Gainsforth Z, Engrand C, Duprat J, Russell SS, Bonato E, Ma C, Kawamoto T, Wada T, Watanabe S, Endo R, Enju S, Riu L, Rubino S, Tack P, Takeshita S, Takeichi Y, Takeuchi A, Takigawa A, Takir D, Tanigaki T, Taniguchi A, Tsukamoto K, Yagi T, Yamada S, Yamamoto K, Yamashita Y, Yasutake M, Uesugi K, Umegaki I, Chiu I, Ishizaki T, Okumura S, Palomba E, Pilorget C, Potin SM, Alasli A, Anada S, Araki Y, Sakatani N, Schultz C, Sekizawa O, Sitzman SD, Sugiura K, Sun M, Dartois E, De Pauw E, Dionnet Z, Djouadi Z, Falkenberg G, Fujita R, Fukuma T, Gearba IR, Hagiya K, Hu MY, Kato T, Kawamura T, Kimura M, Kubo MK, Langenhorst F, Lantz C, Lavina B, Lindner M, Zhao J, Vekemans B, Baklouti D, Bazi B, Borondics F, Nagasawa S, Nishiyama G, Nitta K, Mathurin J, Matsumoto T, Mitsukawa I, Miura H, Miyake A, Miyake Y, Yurimoto H, Okazaki R, Yabuta H, Naraoka H, Sakamoto K, Tachibana S, Connolly HC Jr, Lauretta DS, Yoshitake M, Yoshikawa M, Yoshikawa K, Yoshihara K, Yokota Y, Yogata K, Yano H, Yamamoto Y, Yamamoto D, Yamada M, Yamada T, Yada T, Wada K, Usui T, Tsukizaki R, Terui F, Takeuchi H, Takei Y, Iwamae A, Soejima H, Shirai K, Shimaki Y, Senshu H, Sawada H, Saiki T, Ozaki M, Ono G, Okada T, Ogawa N, Ogawa K, Noguchi R, Noda H, Nishimura M, Namiki N, Nakazawa S, Morota T, Miyazaki A, Miura A, Mimasu Y, Matsumoto K, Kumagai K, Kouyama T, Kikuchi S, Kawahara K, Kameda S, Iwata T, Ishihara Y, Ishiguro M, Ikeda H, Hosoda S, Honda R, Honda C, Hitomi Y, Hirata N, Hirata N, Hayashi T, Hayakawa M, Hatakeda K, Furuya S, Fukai R, Fujii A, Cho Y, Arakawa M, Abe M, Watanabe S, and Tsuda Y
- Abstract
Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu's parent body formed ~2 million years after the beginning of Solar System formation.
- Published
- 2023
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29. Spacecraft sample collection and subsurface excavation of asteroid (101955) Bennu.
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Lauretta DS, Adam CD, Allen AJ, Ballouz RL, Barnouin OS, Becker KJ, Becker T, Bennett CA, Bierhaus EB, Bos BJ, Burns RD, Campins H, Cho Y, Christensen PR, Church ECA, Clark BE, Connolly HC Jr, Daly MG, DellaGiustina DN, Drouet d'Aubigny CY, Emery JP, Enos HL, Kasper SF, Garvin JB, Getzandanner K, Golish DR, Hamilton VE, Hergenrother CW, Kaplan HH, Keller LP, Lessac-Chenen EJ, Liounis AJ, Ma H, McCarthy LK, Miller BD, Moreau MC, Morota T, Nelson DS, Nolau JO, Olds R, Pajola M, Pelgrift JY, Polit AT, Ravine MA, Reuter DC, Rizk B, Rozitis B, Ryan AJ, Sahr EM, Sakatani N, Seabrook JA, Selznick SH, Skeen MA, Simon AA, Sugita S, Walsh KJ, Westermann MM, Wolner CWV, and Yumoto K
- Abstract
Carbonaceous asteroids, such as (101955) Bennu, preserve material from the early Solar System, including volatile compounds and organic molecules. We report spacecraft imaging and spectral data collected during and after retrieval of a sample from Bennu's surface. The sampling event mobilized rocks and dust into a debris plume, excavating a 9-meter-long elliptical crater. This exposed material is darker, spectrally redder, and more abundant in fine particulates than the original surface. The bulk density of the displaced subsurface material was 500 to 700 kilograms per cubic meter, which is about half that of the whole asteroid. Particulates that landed on instrument optics spectrally resemble aqueously altered carbonaceous meteorites. The spacecraft stored 250 ± 101 grams of material, which will be delivered to Earth in 2023.
- Published
- 2022
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30. Pebbles and sand on asteroid (162173) Ryugu: In situ observation and particles returned to Earth.
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Tachibana S, Sawada H, Okazaki R, Takano Y, Sakamoto K, Miura YN, Okamoto C, Yano H, Yamanouchi S, Michel P, Zhang Y, Schwartz S, Thuillet F, Yurimoto H, Nakamura T, Noguchi T, Yabuta H, Naraoka H, Tsuchiyama A, Imae N, Kurosawa K, Nakamura AM, Ogawa K, Sugita S, Morota T, Honda R, Kameda S, Tatsumi E, Cho Y, Yoshioka K, Yokota Y, Hayakawa M, Matsuoka M, Sakatani N, Yamada M, Kouyama T, Suzuki H, Honda C, Yoshimitsu T, Kubota T, Demura H, Yada T, Nishimura M, Yogata K, Nakato A, Yoshitake M, Suzuki AI, Furuya S, Hatakeda K, Miyazaki A, Kumagai K, Okada T, Abe M, Usui T, Ireland TR, Fujimoto M, Yamada T, Arakawa M, Connolly HC Jr, Fujii A, Hasegawa S, Hirata N, Hirata N, Hirose C, Hosoda S, Iijima Y, Ikeda H, Ishiguro M, Ishihara Y, Iwata T, Kikuchi S, Kitazato K, Lauretta DS, Libourel G, Marty B, Matsumoto K, Michikami T, Mimasu Y, Miura A, Mori O, Nakamura-Messenger K, Namiki N, Nguyen AN, Nittler LR, Noda H, Noguchi R, Ogawa N, Ono G, Ozaki M, Senshu H, Shimada T, Shimaki Y, Shirai K, Soldini S, Takahashi T, Takei Y, Takeuchi H, Tsukizaki R, Wada K, Yamamoto Y, Yoshikawa K, Yumoto K, Zolensky ME, Nakazawa S, Terui F, Tanaka S, Saiki T, Yoshikawa M, Watanabe S, and Tsuda Y
- Abstract
The Hayabusa2 spacecraft investigated the C-type (carbonaceous) asteroid (162173) Ryugu. The mission performed two landing operations to collect samples of surface and subsurface material, the latter exposed by an artificial impact. We present images of the second touchdown site, finding that ejecta from the impact crater was present at the sample location. Surface pebbles at both landing sites show morphological variations ranging from rugged to smooth, similar to Ryugu's boulders, and shapes from quasi-spherical to flattened. The samples were returned to Earth on 6 December 2020. We describe the morphology of >5 grams of returned pebbles and sand. Their diverse color, shape, and structure are consistent with the observed materials of Ryugu; we conclude that they are a representative sample of the asteroid.
- Published
- 2022
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31. Variations in color and reflectance on the surface of asteroid (101955) Bennu.
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DellaGiustina DN, Burke KN, Walsh KJ, Smith PH, Golish DR, Bierhaus EB, Ballouz RL, Becker TL, Campins H, Tatsumi E, Yumoto K, Sugita S, Deshapriya JDP, Cloutis EA, Clark BE, Hendrix AR, Sen A, Al Asad MM, Daly MG, Applin DM, Avdellidou C, Barucci MA, Becker KJ, Bennett CA, Bottke WF, Brodbeck JI, Connolly HC Jr, Delbo M, de Leon J, Drouet d'Aubigny CY, Edmundson KL, Fornasier S, Hamilton VE, Hasselmann PH, Hergenrother CW, Howell ES, Jawin ER, Kaplan HH, Le Corre L, Lim LF, Li JY, Michel P, Molaro JL, Nolan MC, Nolau J, Pajola M, Parkinson A, Popescu M, Porter NA, Rizk B, Rizos JL, Ryan AJ, Rozitis B, Shultz NK, Simon AA, Trang D, Van Auken RB, Wolner CWV, and Lauretta DS
- Abstract
Visible-wavelength color and reflectance provide information about the geologic history of planetary surfaces. Here we present multispectral images (0.44 to 0.89 micrometers) of near-Earth asteroid (101955) Bennu. The surface has variable colors overlain on a moderately blue global terrain. Two primary boulder types are distinguishable by their reflectance and texture. Space weathering of Bennu surface materials does not simply progress from red to blue (or vice versa). Instead, freshly exposed, redder surfaces initially brighten in the near-ultraviolet region (i.e., become bluer at shorter wavelengths), then brighten in the visible to near-infrared region, leading to Bennu's moderately blue average color. Craters indicate that the time scale of these color changes is ~10
5 years. We attribute the reflectance and color variation to a combination of primordial heterogeneity and varying exposure ages., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)- Published
- 2020
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32. Bright carbonate veins on asteroid (101955) Bennu: Implications for aqueous alteration history.
- Author
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Kaplan HH, Lauretta DS, Simon AA, Hamilton VE, DellaGiustina DN, Golish DR, Reuter DC, Bennett CA, Burke KN, Campins H, Connolly HC Jr, Dworkin JP, Emery JP, Glavin DP, Glotch TD, Hanna R, Ishimaru K, Jawin ER, McCoy TJ, Porter N, Sandford SA, Ferrone S, Clark BE, Li JY, Zou XD, Daly MG, Barnouin OS, Seabrook JA, and Enos HL
- Abstract
The composition of asteroids and their connection to meteorites provide insight into geologic processes that occurred in the early Solar System. We present spectra of the Nightingale crater region on near-Earth asteroid Bennu with a distinct infrared absorption around 3.4 micrometers. Corresponding images of boulders show centimeters-thick, roughly meter-long bright veins. We interpret the veins as being composed of carbonates, similar to those found in aqueously altered carbonaceous chondrite meteorites. If the veins on Bennu are carbonates, fluid flow and hydrothermal deposition on Bennu's parent body would have occurred on kilometer scales for thousands to millions of years. This suggests large-scale, open-system hydrothermal alteration of carbonaceous asteroids in the early Solar System., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2020
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33. Bennu's near-Earth lifetime of 1.75 million years inferred from craters on its boulders.
- Author
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Ballouz RL, Walsh KJ, Barnouin OS, DellaGiustina DN, Asad MA, Jawin ER, Daly MG, Bottke WF, Michel P, Avdellidou C, Delbo M, Daly RT, Asphaug E, Bennett CA, Bierhaus EB, Connolly HC Jr, Golish DR, Molaro JL, Nolan MC, Pajola M, Rizk B, Schwartz SR, Trang D, Wolner CWV, and Lauretta DS
- Abstract
An asteroid's history is determined in large part by its strength against collisions with other objects
1,2 (impact strength). Laboratory experiments on centimetre-scale meteorites3 have been extrapolated and buttressed with numerical simulations to derive the impact strength at the asteroid scale4,5 . In situ evidence of impacts on boulders on airless planetary bodies has come from Apollo lunar samples6 and images of the asteroid (25143) Itokawa7 . It has not yet been possible, however, to assess directly the impact strength, and thus the absolute surface age, of the boulders that constitute the building blocks of a rubble-pile asteroid. Here we report an analysis of the size and depth of craters observed on boulders on the asteroid (101955) Bennu. We show that the impact strength of metre-sized boulders is 0.44 to 1.7 megapascals, which is low compared to that of solid terrestrial materials. We infer that Bennu's metre-sized boulders record its history of impact by millimetre- to centimetre-scale objects in near-Earth space. We conclude that this population of near-Earth impactors has a size frequency distribution similar to that of metre-scale bolides and originates from the asteroidal population. Our results indicate that Bennu has been dynamically decoupled from the main asteroid belt for 1.75 ± 0.75 million years.- Published
- 2020
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34. Meteoroid Impacts as a Source of Bennu's Particle Ejection Events.
- Author
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Bottke WF, Moorhead AV, Connolly HC Jr, Hergenrother CW, Molaro JL, Michel P, Nolan MC, Schwartz SR, Vokrouhlický D, Walsh KJ, and Lauretta DS
- Abstract
Asteroid (101955) Bennu, a near-Earth object with a primitive carbonaceous chondrite-like composition, was observed by the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) spacecraft to undergo multiple particle ejection events near perihelion between December 2018 and February 2019. The three largest events observed during this period, which all occurred 3.5 to 6 hr after local noon, placed numerous particles <10 cm on temporary orbits around Bennu. Here we examine whether these events could have been produced by sporadic meteoroid impacts using the National Aeronautics and Space Administration's (NASA) Meteoroid Engineering Model 3.0. Most projectiles that impact Bennu come from nearly isotropic or Jupiter-family comets and have evolved toward the Sun by Poynting-Robertson drag. We find that 7,000-J impacts on Bennu occur with a biweekly cadence near perihelion, with a preference to strike in the late afternoon (~6 pm local time). This timing matches observations. Crater scaling laws also indicate that these impact energies can reproduce the sizes and masses of the largest observed particles, provided the surface has the cohesive properties of weak, porous materials. Bennu's ejection events could be caused by the same kinds of meteoroid impacts that created the Moon's asymmetric debris cloud observed by the Lunar Atmosphere and Dust Environment Explorer (LADEE). Our findings also suggest that fewer ejection events should take place as Bennu moves further away from the Sun, a result that can be tested with future observations., (©2020. The Authors.)
- Published
- 2020
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35. Meteoritic Evidence for a Ceres-sized Water-rich Carbonaceous Chondrite Parent Asteroid.
- Author
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Hamilton VE, Goodrich CA, Treiman AH, Connolly HC Jr, Zolensky ME, and Shaddad MH
- Abstract
Carbonaceous chondrite meteorites record the earliest stages of Solar System geo-logical activities and provide insight into their parent bodies' histories. Some carbonaceous chondrites are volumetrically dominated by hydrated minerals, providing evidence for low temperature and pressure aqueous alteration
1 . Others are dominated by anhydrous minerals and textures that indicate high temperature metamorphism in the absence of aqueous fluids1 . Evidence of hydrous metamorphism at intermediate pressures and temperatures in carbonaceous chondrite parent bodies has been virtually absent. Here we show that an ungrouped, aqueously altered carbonaceous chondrite fragment (numbered 202) from the Almahata Sitta (AhS) meteorite contains an assemblage of minerals, including amphibole, that reflect fluid-assisted metamorphism at intermediate temperatures and pressures on the parent asteroid. Amphiboles are rare in carbonaceous chondrites, having only been identified previously as a trace component in Allende (CV3oxA ) chondrules2 . Formation of these minerals requires prolonged metamorphism in a large (~640-1800 km diameter), unknown asteroid. Because Allende and AhS 202 represent different asteroidal parent bodies, intermediate conditions may have been more widespread in the early Solar System than recognized from known carbonaceous chondrite meteorites, which are likely a biased sampling., Competing Interests: Competing Interests The authors declare no competing interests.- Published
- 2020
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36. Episodes of particle ejection from the surface of the active asteroid (101955) Bennu.
- Author
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Lauretta DS, Hergenrother CW, Chesley SR, Leonard JM, Pelgrift JY, Adam CD, Al Asad M, Antreasian PG, Ballouz RL, Becker KJ, Bennett CA, Bos BJ, Bottke WF, Brozović M, Campins H, Connolly HC Jr, Daly MG, Davis AB, de León J, DellaGiustina DN, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Farnocchia D, Glavin DP, Golish DR, Hartzell CM, Jacobson RA, Jawin ER, Jenniskens P, Kidd JN Jr, Lessac-Chenen EJ, Li JY, Libourel G, Licandro J, Liounis AJ, Maleszewski CK, Manzoni C, May B, McCarthy LK, McMahon JW, Michel P, Molaro JL, Moreau MC, Nelson DS, Owen WM Jr, Rizk B, Roper HL, Rozitis B, Sahr EM, Scheeres DJ, Seabrook JA, Selznick SH, Takahashi Y, Thuillet F, Tricarico P, Vokrouhlický D, and Wolner CWV
- Abstract
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances of particle ejection from the surface of (101955) Bennu, demonstrating that it is an active asteroid. The ejection events were imaged by the OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For the three largest observed events, we estimated the ejected particle velocities and sizes, event times, source regions, and energies. We also determined the trajectories and photometric properties of several gravitationally bound particles that orbited temporarily in the Bennu environment. We consider multiple hypotheses for the mechanisms that lead to particle ejection for the largest events, including rotational disruption, electrostatic lofting, ice sublimation, phyllosilicate dehydration, meteoroid impacts, thermal stress fracturing, and secondary impacts., (Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.)
- Published
- 2019
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37. The dynamic geophysical environment of (101955) Bennu based on OSIRIS-REx measurements.
- Author
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Scheeres DJ, McMahon JW, French AS, Brack DN, Chesley SR, Farnocchia D, Takahashi Y, Leonard JM, Geeraert J, Page B, Antreasian P, Getzandanner K, Rowlands D, Mazarico E, Small J, Highsmith DE, Moreau M, Emery JP, Rozitis B, Hirabayashi M, Sánchez P, Wal SV, Tricarico P, Ballouz RL, Johnson CL, Asad MMA, Susorney HCM, Barnouin OS, Daly MG, Seabrook J, Gaskell RW, Palmer EE, Weirich JR, Walsh KJ, Jawin ER, Bierhaus EB, Michel P, Bottke WF, Nolan MC, Connolly HC Jr, and Lauretta DS
- Abstract
The top-shape morphology of asteroid (101955) Bennu is commonly found among fast-spinning asteroids and binary asteroid primaries, and might have contributed significantly to binary asteroid formation. Yet a detailed geophysical analysis of this morphology for a fast-spinning asteroid has not been possible prior to the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission. Combining the measured Bennu mass and shape obtained during the Preliminary Survey phase of OSIRIS-REx, we find a significant transition in Bennu's surface slopes within its rotational Roche lobe, defined as the region where material is energetically trapped to the surface. As the intersection of the rotational Roche lobe with Bennu's surface has been most recently migrating towards its equator (given Bennu's increasing spin rate), we infer that Bennu's surface slopes have been changing across its surface within the last million years. We also find evidence for substantial density heterogeneity within this body, suggesting that its interior has a distribution of voids and boulders. The presence of such heterogeneity and Bennu's top-shape is consistent with spin-induced failure at some point in its past, although the manner of its failure cannot be determined yet. Future measurements by the OSIRIS-REx spacecraft will give additional insights and may resolve questions regarding the formation and evolution of Bennu's top-shape morphology and its link to the formation of binary asteroids.
- Published
- 2019
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38. The unexpected surface of asteroid (101955) Bennu.
- Author
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Lauretta DS, DellaGiustina DN, Bennett CA, Golish DR, Becker KJ, Balram-Knutson SS, Barnouin OS, Becker TL, Bottke WF, Boynton WV, Campins H, Clark BE, Connolly HC Jr, Drouet d'Aubigny CY, Dworkin JP, Emery JP, Enos HL, Hamilton VE, Hergenrother CW, Howell ES, Izawa MRM, Kaplan HH, Nolan MC, Rizk B, Roper HL, Scheeres DJ, Smith PH, Walsh KJ, and Wolner CWV
- Subjects
- Exobiology, Origin of Life, Surface Properties, Extraterrestrial Environment chemistry, Minor Planets, Space Flight instrumentation
- Abstract
NASA'S Origins, Spectral Interpretation, Resource Identification and Security-Regolith Explorer (OSIRIS-REx) spacecraft recently arrived at the near-Earth asteroid (101955) Bennu, a primitive body that represents the objects that may have brought prebiotic molecules and volatiles such as water to Earth
1 . Bennu is a low-albedo B-type asteroid2 that has been linked to organic-rich hydrated carbonaceous chondrites3 . Such meteorites are altered by ejection from their parent body and contaminated by atmospheric entry and terrestrial microbes. Therefore, the primary mission objective is to return a sample of Bennu to Earth that is pristine-that is, not affected by these processes4 . The OSIRIS-REx spacecraft carries a sophisticated suite of instruments to characterize Bennu's global properties, support the selection of a sampling site and document that site at a sub-centimetre scale5-11 . Here we consider early OSIRIS-REx observations of Bennu to understand how the asteroid's properties compare to pre-encounter expectations and to assess the prospects for sample return. The bulk composition of Bennu appears to be hydrated and volatile-rich, as expected. However, in contrast to pre-encounter modelling of Bennu's thermal inertia12 and radar polarization ratios13 -which indicated a generally smooth surface covered by centimetre-scale particles-resolved imaging reveals an unexpected surficial diversity. The albedo, texture, particle size and roughness are beyond the spacecraft design specifications. On the basis of our pre-encounter knowledge, we developed a sampling strategy to target 50-metre-diameter patches of loose regolith with grain sizes smaller than two centimetres4 . We observe only a small number of apparently hazard-free regions, of the order of 5 to 20 metres in extent, the sampling of which poses a substantial challenge to mission success.- Published
- 2019
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39. Evidence for widespread hydrated minerals on asteroid (101955) Bennu.
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Hamilton VE, Simon AA, Christensen PR, Reuter DC, Clark BE, Barucci MA, Bowles NE, Boynton WV, Brucato JR, Cloutis EA, Connolly HC Jr, Hanna KLD, Emery JP, Enos HL, Fornasier S, Haberle CW, Hanna RD, Howell ES, Kaplan HH, Keller LP, Lantz C, Li JY, Lim LF, McCoy TJ, Merlin F, Nolan MC, Praet A, Rozitis B, Sandford SA, Schrader DL, Thomas CA, Zou XD, and Lauretta DS
- Abstract
Early spectral data from the Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer (OSIRIS-REx) mission reveal evidence for abundant hydrated minerals on the surface of near-Earth asteroid (101955) Bennu in the form of a near-infrared absorption near 2.7 μm and thermal infrared spectral features that are most similar to those of aqueously altered CM carbonaceous chondrites. We observe these spectral features across the surface of Bennu, and there is no evidence of substantial rotational variability at the spatial scales of tens to hundreds of meters observed to date. In the visible and near-infrared (0.4 to 2.4 μm) Bennu's spectrum appears featureless and with a blue (negative) slope, confirming previous ground-based observations. Bennu may represent a class of objects that could have brought volatiles and organic chemistry to Earth.
- Published
- 2019
- Full Text
- View/download PDF
40. OSIRIS-REx Contamination Control Strategy and Implementation.
- Author
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Dworkin JP, Adelman LA, Ajluni T, Andronikov AV, Aponte JC, Bartels AE, Beshore E, Bierhaus EB, Brucato JR, Bryan BH, Burton AS, Callahan MP, Castro-Wallace SL, Clark BC, Clemett SJ, Connolly HC Jr, Cutlip WE, Daly SM, Elliott VE, Elsila JE, Enos HL, Everett DF, Franchi IA, Glavin DP, Graham HV, Hendershot JE, Harris JW, Hill SL, Hildebrand AR, Jayne GO, Jenkens RW Jr, Johnson KS, Kirsch JS, Lauretta DS, Lewis AS, Loiacono JJ, Lorentson CC, Marshall JR, Martin MG, Matthias LL, McLain HL, Messenger SR, Mink RG, Moore JL, Nakamura-Messenger K, Nuth JA 3rd, Owens CV, Parish CL, Perkins BD, Pryzby MS, Reigle CA, Righter K, Rizk B, Russell JF, Sandford SA, Schepis JP, Songer J, Sovinski MF, Stahl SE, Thomas-Keprta K, Vellinga JM, and Walker MS
- Abstract
OSIRIS-REx will return pristine samples of carbonaceous asteroid Bennu. This article describes how pristine was defined based on expectations of Bennu and on a realistic understanding of what is achievable with a constrained schedule and budget, and how that definition flowed to requirements and implementation. To return a pristine sample, the OSIRIS-REx spacecraft sampling hardware was maintained at level 100 A/2 and <180 ng/cm
2 of amino acids and hydrazine on the sampler head through precision cleaning, control of materials, and vigilance. Contamination is further characterized via witness material exposed to the spacecraft assembly and testing environment as well as in space. This characterization provided knowledge of the expected background and will be used in conjunction with archived spacecraft components for comparison with the samples when they are delivered to Earth for analysis. Most of all, the cleanliness of the OSIRIS-REx spacecraft was achieved through communication among scientists, engineers, managers, and technicians.- Published
- 2018
- Full Text
- View/download PDF
41. Ancient asteroids enriched in refractory inclusions.
- Author
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Sunshine JM, Connolly HC Jr, McCoy TJ, Bus SJ, and La Croix LM
- Abstract
Calcium- and aluminum-rich inclusions (CAIs) occur in all classes of chondritic meteorites and contain refractory minerals predicted to be the first condensates from the solar nebula. Near-infrared spectra of CAIs have strong 2-micrometer absorptions, attributed to iron oxide-bearing aluminous spinel. Similar absorptions are present in the telescopic spectra of several asteroids; modeling indicates that these contain approximately 30 +/- 10% CAIs (two to three times that of any meteorite). Survival of these undifferentiated, large (50- to 100-kilometer diameter) CAI-rich bodies suggests that they may have formed before the injection of radiogenic 26Al into the solar system. They have also experienced only modest post-accretionary alteration. Thus, these asteroids have higher concentrations of CAI material, appear less altered, and are more ancient than any known sample in our meteorite collection, making them prime candidates for sample return.
- Published
- 2008
- Full Text
- View/download PDF
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