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1,498 results on '"Jacobson, R. A"'

54. Higher stabilization and higher Freudenthal suspension.

Author

Blomquist, Jacobson R. and Harper, John E.

Subjects
*HOMOTOPY equivalences
Abstract

We prove that the stabilization (resp. iterated suspension) functor participates in a derived adjunction comparing pointed spaces with certain (highly homotopy coherent) homotopy coalgebras, in the sense of Blumberg-Riehl, that is a Dwyer-Kan equivalence after restriction to 1-connected spaces, with respect to the associated enrichments. A key ingredient of our proof, of independent interest, is a higher stabilization theorem (resp. higher Freudenthal suspension theorem) for pointed spaces that provides strong estimates for the uniform cartesian-ness of certain cubical diagrams associated to iterating the space level stabilization map (resp. Freudenthal suspension map)—these technical results provide, in particular, new proofs (with strong estimates) of the stabilization and iterated loop-suspension completion results of Carlsson and the subsequent work of Arone-Kankaanrinta, and Bousfield and Hopkins, respectively, for 1-connected spaces; this is the stabilization (resp. Freudenthal suspension) analog of Dundas' higher Hurewicz theorem. [ABSTRACT FROM AUTHOR]

Published
2022
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55. Integral chains and Bousfield–Kan completion

Author

Jacobson R. Blomquist and John E. Harper

Subjects
Subcategory, Pure mathematics, Homotopy, Coalgebra, Homology (mathematics), Adjunction, Mathematics::Algebraic Topology, Mathematics (miscellaneous), Mathematics::K-Theory and Homology, Mathematics::Category Theory, Simply connected space, Unit (ring theory), Mathematics, Descent (mathematics)
Abstract

Working in the Arone-Ching framework for homotopical descent, it follows that the Bousfield-Kan completion map with respect to integral homology is the unit of a derived adjunction. We prove that this derived adjunction, comparing spaces with coalgebra complexes over the associated integral homology comonad, via integral chains, can be turned into a derived equivalence by replacing spaces with the full subcategory of simply connected spaces. In particular, this provides an integral chains characterization of the homotopy type of simply connected spaces.

Published
2019
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56. Mining amid armed conflict: nonferrous metals mining in the Philippines

Author

Holden, William N. and Jacobson, R. Daniel

Subjects
Philippines -- Economic aspects, Mineral industry -- Research, Mining industry -- Research, Rebels -- Influence, Geography
Abstract

A study was conducted to examine how the activities and presence of anti-state groups in the Philippines create problems for a mining-based development paradigm. Findings show that violence is a sign of problems such as poverty and social exclusion in the country. It is expected that violence will continue unless these problems are alleviated.

Published
2007

58. Mining amid decentralization. Local governments and mining in the Philippines

Author

Holden, William N. and Jacobson, R. Daniel

Subjects
Local government, Mineral industry, Mining industry, Environmental issues, Geography
Abstract

To purchase or authenticate to the full-text of this article, please visit this link: http://dx.doi.org/10.1111/j.1477-8947.2006.00108.x Byline: William N. Holden (1), R. Daniel Jacobson (2) Keywords: Philippines; Mining; Decentralization; Civil society; Governance Abstract: Abstract In recent years, as part of its neoliberal development paradigm, the Government of the Philippines has engaged in efforts to encourage extraction of the nation's mineral resources. The Philippines is also a country where decentralization has devolved substantial powers to local governments. Concern over potentially adverse environmental effects has led to opposition to mining by some local governments in the Philippines. This opposition has led to the withholding of consent to mining projects by local governments and, in some cases, the implementation of moratoriums banning mining. Central to this opposition have been the activities of civil society groups, and their collaboration with local governments. This collaboration has involved the drafting of legislation prohibiting mining and support of candidates for office who are opposed to mining. Collectively, Filipino local governments and civil society groups are examples of the concept of governance, a dispersed process wherein society manages itself for the betterment of all its members. For mining companies seeking to implement projects, it is no longer sufficient to have the consent of the national Government - that of local governance forces must also be considered. Author Affiliation: (1)Dept of Geography/Program of Environmental Science, University of Calgary, Alberta, Canada (2)Dept of Geography, University of Calgary

Published
2006

59. Enzymatic Degradation of Insoluble Carbohydrates

Author

JOHN N. SADDLER, MICHAEL H. PENNER, David B. Wilson, Mike Spezio, Diana Irwin, Andrew Karplus, Jeff Taylor, A. D. French, M. K. Dowd, S. K. Cousins, R. M. Brown, D. P. Miller, R. H. Jacobson, R. Kuroki, L. H. Weaver, X-J. Zhang, B. W. Matthews, C. A. Henson, Z. Sun, Jon D. Robertus, John Hart, Edwar

Published
1996

60. Design considerations for haptic and auditory map interfaces

Author

Rice, Matt, Jacobson, R. Daniel, Golledge, Reginald G., and Jones, David

Subjects
Spatial analysis (Statistics) -- Usage -- Research, Communication -- Research -- Usage, Tactile maps (Geography) -- Usage -- Research, Blind -- Services -- Research -- Usage, Geography
Abstract

Communicating spatial information to the blind and visually impaired using maps and graphics presents many difficulties. Past research has offered advice to cartographers on topics such as tactile areal, point, and line symbolization; on perceptual problems related to dense linear features on tactile maps; and on the relationship between categorical data, measurement theory, and tactile discrimination. With this previous work as a foundation, we describe our research efforts with haptic and auditory maps--the Haptic Soundscapes Project. Haptic Soundscapes maps allow blind and visually-impaired individuals to feel map features through force feedback devices and hear auditory cues that add both redundant and complementary information. Recent experimental work by the authors has led to several recommended practices for cartographic data simplification, object size discrimination, shape identification, and general interface navigation. The authors also present haptic and auditory mapping examples to illustrate design ideas, algorithms, and technical requirements. Future prospects for automated haptic and auditory map creation are discussed and presented in the context of the past work in generating maps for the blind and visually impaired from cartographic data., Communicating Spatial Information to the Blind Two major obstacles that blind and visually impaired individuals face in becoming fully functioning members of our modern society are access to print media [...]

Published
2005

61. A commentary on the use of touch for accessing on-screen spatial representations: the process of experiencing haptic maps and graphics

Author

Golledge, Reginald G., Rice, Matthew, and Jacobson, R. Daniel

Subjects
Geography -- Research, Geography -- Equipment and supplies, Digital mapping -- Research, Digital mapping -- Usage, Geography
Abstract

The growth of the Internet and the digital revolution have meant increased reliance on electronic representations of information. Geospatial information has been readily adapted to the world of cyberspace, and most Web pages incorporate graphics, images, or maps to represent spatial and spatialized data. But flat computer screens do not facilitate a map or graph experience by those who are visually impaired. The traditional method for compensating for nonvisual access to maps and graphics has been to construct hard-copy tactile maps. In this article, we examine an electronic accommodation for nonvisual users--the haptic map. Using new and off-the-shelf hardware--force feedback and vibrotactile mice--we explore how touch can be combined with virtual representations of shapes and patterns to enable nonvisual access to onscreen map or graphic material. Key Words: digital representation, haptic maps, visual impairment.

Published
2005

64. Does Social Vulnerability Index Correlate to Adverse Outcomes in Soft Tissue Sarcoma?

Author

Jacobson, R., Poultsides, G., Grignol, V., Howard, H., Chouliaras, K., Votanopoulos, K., Cullinan, D., Fields, R.C., Cardona, K., and Bedi, M.

Subjects
*PROPORTIONAL hazards models, *SARCOMA, *ZIP codes, *ABDOMINAL wall, *LOG-rank test
Abstract

Social determinants of health play a role in outcomes of many cancers. Socioeconomic and demographic factors have been used to examine disparities in survival among cancer patients, including the CDC Social Vulnerability Index (SVI). Although there is data on SVI in other cancers, the impact of SVI and STS outcomes are poorly understood. The objective of this study was to determine if SVI is associated with recurrence free survival (RFS) and overall survival (OS) in patients with STS. A retrospective study was done using the US Sarcoma Collaborative multi-institutional database from 2000-2016. Age ≥18 years, stage I-IV extremity and truncal/abdominal wall STS with available zip code data were included. Zip codes were geocoded to the census tract level and matched to social vulnerability values from the CDC SVI. Social vulnerability values ranged from 0-1 with 0 being the least vulnerable and 1 being the most vulnerable. OS and RFS were calculated using Kaplan-Meier survival analyses. Prognostic variables (Table 1) were determined by univariate analysis (UVA) using the log-rank test and multivariate analyses (MVA) using the Cox proportional hazards model. 511 patients were included in the analysis. Median follow-up was 59 mo. 2-year OS and RFS was 67% and 45%, respectively. Mean nationwide SVI of patients was 0.58 and mean statewide SVI was 0.48 as compared to all censuses. On MVA, any complication (p<0.0001, 95% CI, 48.3-68.3), poor functional status (p = 0.02, 95% CI 1.8 -205.3), patients of Hispanic descent (p = 0.004, 95% CI 3.1-400.2), high grade (p = 0.008, 95% CI 0.06- 0.65), increased tumor size (p<0.0001, 95% CI 1.1-1.6) and high nationwide SVI (p = 0.03, 95% CI 1.2- 256.4) were associated with poor OS and stage IV (p = 0.006, 95% CI 1.25-3.9), high grade (p = 0.04, 95% CI 0.17-0.94) and poor functional status (p = 0.0013, 95% CI 4.38 - 456.8) were associated with RFS. In this study of patients with STS, high SVI was associated with decreased OS. These findings suggest that the SVI may be used as a tool for identifying where resources can be targeted at a national level to mediate the survival disparity for vulnerable populations with sarcoma, however further investigation is warranted. [ABSTRACT FROM AUTHOR]

Published
2024
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67. Chromatography in Biotechnology

Author

CSABA HORVÁTH, LESLIE S. ETTRE, John Frenz, T. K. Nadler, F. E. Regnier, Steven M. Cramer, Clayton A. Brooks, Walter F. Prouty, R. S. Hodges, T. W. L. Burke, A. J. Mendonca, C. T. Mant, Jana Jacobson, R. Reid Townsend, Henryk M. Kalisz, Rolf D. Schmid, P. H. Roos, Charlotte C. Yu Ip, William J. Mill

Published
1993

70. Trajectory Estimation for Particles Observed in the Vicinity of (101955) Bennu

Author

Chesley, S. R., primary, French, A. S., additional, Davis, A. B., additional, Jacobson, R. A., additional, Brozović, M., additional, Farnocchia, D., additional, Selznick, S., additional, Liounis, A. J., additional, Hergenrother, C. W., additional, Moreau, M. C., additional, Pelgrift, J., additional, Lessac‐Chenen, E., additional, Molaro, J. L., additional, Park, R. S., additional, Rozitis, B., additional, Scheeres, D. J., additional, Takahashi, Y., additional, Vokrouhlický, D., additional, Wolner, C. W. V., additional, Adam, C., additional, Bos, B. J., additional, Christensen, E. J., additional, Emery, J. P., additional, Leonard, J. M., additional, McMahon, J. W., additional, Nolan, M. C., additional, Shelly, F. C., additional, and Lauretta, D. S., additional

Published
2020
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71. Photometry of Particles Ejected From Active Asteroid (101955) Bennu

Author

Hergenrother, C. W., primary, Maleszewski, C., additional, Li, J.‐Y., additional, Pajola, M., additional, Chesley, S. R., additional, French, A. S., additional, Davis, A. B., additional, Pelgrift, J. Y., additional, Leonard, J. M., additional, Shelly, F., additional, Liounis, A. J., additional, Becker, K., additional, Balram‐Knutson, S. S., additional, Garcia, R., additional, Kareta, T. R., additional, Adam, C., additional, Alkiek, K., additional, Bos, B. J., additional, Brozović, M., additional, Burke, K. N., additional, Christensen, E., additional, Clark, B. E., additional, DellaGiustina, D. N., additional, Drouet d'Aubigny, C., additional, Farnocchia, D., additional, Howell, E. S., additional, Jacobson, R. A., additional, Kidd, J. N., additional, Lessac‐Chenen, E. J., additional, Melikyan, R., additional, Nolan, M. C., additional, Park, R. S., additional, Selznick, S., additional, Rizk, B., additional, and Lauretta, D. S., additional

Published
2020
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73. Does Vesta Have Moons?: Dawn's Search for Satellites

Author

McFadden, L. A, Sykes, M. V, Tricarico, P, Carsenty, U, Gutierrez-Marques, P, Jacobson, R. A, Joy, S, Keller, H. U, Li, J.-Y, McLean, B, Memarsadeghi, N, Mottola, S, Mutchler, M, Nathues, A, OBrien, D, Palmer, E, Polanskey, C, Sierks, H, Rayman, M. D, Raymond, C. A, Russell, C. T, Schroeder, S, Skillman, D, and Weinstein-Weiss, S

Subjects
Astronomy
Abstract

Upon approach to asteroid 4 Vesta, the Dawn mission included a dedicated satellite search observation of the operational sphere of the spacecraft around Vesta. Discovery of moons of Vesta would constrain theories of satellite f()rmation. The sequence using the framing camera and clear filter includes three mosaics of six stations acquired on July 9-10. 2011. Each station consists of four sets with three different exposures, 1.5,20 and 270 s. We also processed and scanned the optical navigation sequences until Vesta filled the field of view. Analysis of images involves looking for moving objects in the mosaics and identifying catalogued stars, subtracting them from the image and examining residual objects for evidence of bodies in orbit around Vesta. Celestial coordinates were determined using Astrometry.net, an astrometry calibration service (http://astrometry.net/use.html). We processed the images by subtracting dark and bias fields and dividing by a Hatfield. Images were further filtered subtracting a box car filter (9x9 average) to remove effects of scattered light from Vesta itself. Images were scanned by eye for evidence of motion in directions different from the background stars. All objects were compared with Hubble Space Telescope's Guide Star Catalogue and US Naval Observatory's UCAC3 catalog. We report findings from these observations and analysis, including limits of magnitude, size and motion of objects in orbit around Vesta. We gratefully acknowledge modifications made to Astrometrica http://www.astrometrica.at/ for purposes of this effort.

Published
2011

74. The Pole Orientation, Pole Precession, and Moment of Inertia Factor of Saturn

Author

Jacobson, R. A, French, R. G, Nicholson, P. D, Hedman, M, Colwell, J. E, Marouf, E, Rappaport, N, McGhee, C, Sepersky, T, and Lonergan, K

Subjects
Lunar And Planetary Science And Exploration, Astrophysics
Abstract

This paper discusses our determination of the Saturn's pole orientation and precession using a combination of Earthbased and spacecraft based observational data. From our model of the polar motion and the observed precession rate we obtain a value for Saturn's polar moment of inertia

Published
2011

75. Does Vesta Have Moons?

Author

McFadden, L. A, Sykes, M, Joy, S, Tricarico, P, O'Brien, D, Li, J. Y, Mutchler, M, Memarsadeghi, N, Safavi, H, Gutierrez-Marques, P, Nathues, A, Sierks, H, Schroder, S, Polansky, C, Jacobson, R, Russell, C. T, Raymond, C. A, Rayman, M, Weinstein-Weiss, S, and Palmer, E

Subjects
Lunar And Planetary Science And Exploration
Abstract

Previous searches for moons around Vesta have found nothing to an upper limit of 22.5 magnitude, that corresponds to 44 +/- 4 m diameter assuming the same albedo as Vesta. The Dawn mission's approach phase has dedicated satellite search observations consisting of two mosaic sequences bracketing the first observations of a complete rotation of Vesta scheduled for early July, 2011. In addition, we use the approach optical navigation image sequences for initial satellite searches. We will report any findings from these observations, and upper limits of magnitude and size.

Published
2011

79. Tidal Heating: Lessons from Io and the Jovian System (Report from the KISS Workshop)

Author

Park, R. S., de Kleer, K., McEwen, A., Bierson, C. J., Davies, A. G., DellaGiustina, D., Ermakov, A. I., Fuller, J., Hamilton, C., Harris, C., Hay, H., Jacobson, R. A., Keane, J., Kestay, L., Khurana, K., Kirby, K., Stevenson, D., Tsai, V. C., and Turtle, E.

Abstract

Summary of the Keck Institute for Space Studies workshop entitled "Tidal Heating: Lessons from Io and the Jovian System," held on October 15-19, 2018.

Published
2019

83. Cassini Orbit Determination Results: January 2006 - End of Prime Mission

Author

Antreasian, P. G, Ardalan, S. M, Bordi, J. J, Criddle, K. E, Ionasescu, R, Jacobson, R. A, Jones, J. B, Mackenzie, R. A, Parcher, D. W, Pelletier, F. J, Roth, D. C, Thompson, P. F, and Vaughan, A. T

Subjects
Space Communications, Spacecraft Communications, Command And Tracking, Lunar And Planetary Science And Exploration
Abstract

After the forty-fifth flyby of Titan, the Cassini spacecraft has successfully completed the planned four-year prime mission tour of the Saturnian system. This paper reports on the orbit determination performance of the Cassini spacecraft over two years spanning 2006 - 2008. In this time span, Cassini's orbit progressed through the magnetotail and pi-transfer phases of the mission. Thirty-four accurate close encounters of Titan, one close flyby of Iapetus and one 50 km flyby of Enceladus were performed during this period. The Iapetus and Enceladus flybys were especially challenging and so the orbit determination supporting these encounters will be discussed in more detail. This paper will show that in most cases orbit determination has exceeded the navigation requirements for targeting flybys and predicting science instrument pointing during these encounters.

Published
2008

86. 93rd annual convention podium and poster abstracts

Author

Davis, C. M., Strong, S. A., Hellinger, M. D., Williamson, P. R., Larach, S. W., Ferrara, A., Blake, T. B., Medich, D. S., Ziv, Y., Oakley, J. R., Reissman, P., Piccirillo, M., Ulrich, A., Nogueras, J. J., Wexner, S. D., Rubin, M. S., Bodenstein, L. E., Kent, K. C., Williamson, M. E. R., Lewis, W. G., Sagar, P. M., Holdsworth, P. J., Johnston, D., Fazio, V. W., Goldblum, J. R., Sirimarco, M. T., Lavery, I. C., Petras, R. E., Treem, W. R., Cohen, J., Davis, P. M., Hyams, J. S., Eu, K. W., Bartolo, D. C. C., Green, J. D., Riether, R. D., Rosen, L., Stasik, J. J., Sheets, J. A., Reed, J., Khubchandani, I. T., Armitage, N. C., Chapman, M., Hardcastle, J. D., Viamonte, M., Plasencia, G., Wiltz, O., Jacobs, M., Finan, P. J., Passaro, M., Church, J. M., McGannon, E., Wilson, M., Hull-Boiner, S., Kollmorgen, C. F., Meagher, A. P., Wolff, B. G., Pemberton, J. H., Martenson, J. A., Ilstrup, D. M., Moran, M. R., Ramos, A., Rothenberger, D. A., Goldberg, S. M., Johnson, D., Madoff, R. D., Wong, W. D., Finne, III, C. O., Konishi, F., Furuta, K., Kanazawa, K., Lockhart, D., Schmitt, S., Caushaj, P. P., Garcia-Aguilar, J., Belmonte, C., Schiesel, E. C., Mazier, W. P., Senagore, A. J., Piccirillo, M. F., Teoh, T. -A., Yoon, K. -S., Paul, R. A. Patino, Lucas, J., Nelson, R., Norton, N., Cautley, E., Schouten, W. R., Briel, J. W., Auwerda, J. J. A., de Graaf, E. J. R., Lowry, A. C., Sentovich, S. M., Blatchford, G. J., Rivela, L. J., Thorson, A. G., Christensen, M. A., Jorge, J. M. N., Yang, Y. K., Shafik, A., Allendorf, J. D. F., Kayton, M. L., Libutti, S. K., Trokel, M. J., Whelan, R. L., Treat, M. R., Nowygrod, R., Bessler, M., Frank, R. E., Saclarides, T. J., Leurgans, S., Speziale, N. J., Drab, E., Rubin, D., Hull, T. L., Schroeder, T. K., Scholefield, J. H., Ogunbiyi, O. A., Smith, J. H. F., Rogers, K., Sharp, F., Longo, W. E., Vernava, III, A. M., Wade, T. P., Coplin, M. A., Virgo, K. S., Johnson, F. E., Brady, M., Kavolius, J., Quan, S. H. Q., Goldstein, E. T., Feldman, S., Shub, H. A., Bennett, D. R., Kumar, R., McMillen, M. A., Thornton, S., Khoury, D. A., Opelka, F. G., Teoh, T -A., Cohen, S. M., Weiss, E. G., Ortiz, H., De Miguel, M., Armendáriz, P., Rodriguez, J., Chocarro, C., Farouk, R., Dorrance, H. R., Duthie, G. S., Rainey, J. B., Morgado, Jr., P. J., Corman, M. L., Kawamura, Y. J., Sawada, T., Muto, T., Nagai, H., Hill, J., MacLennan, I., Binderow, S. R., Daniel, N., Ehrenpreis, E. D., Jensen, J. E., Bonner, G. F., Ruderman, W. B., Milsom, J. W., Gibbs, D. H., Beck, D. E., Hicks, T. C., Timmcke, A. E., Gathright, Jr, J. B., Cheong, D., Lucas, F. V., McGinity, M., Taylor, B. A., Godwin, P., Holdsworth, P., Lewis, W., Quirke, P., Williamson, M., Kokoszka, J., Pavel, D., Abcarian, H., Stephenson, B. M., Morgan, A. R., Salaman, J. R., Wheeler, M. H., Tran, T. C. K., Willemsen, W., Kuijpers, H. C., Lehman, J. F., Wiseman, J. S., MacFie, J., Sedman, P., May, J., Mancey-Jones, B., Johnstone, D., Nwariaku, F. E., Rochon, R. B., Huber, P. J., Carrico, C. J., Ortega, A., Beart, R., Winchester, D., Steele, G., Green, R., Caushaj, P. F., Devereaux, D., Griffey, S., Reiver, D., Kmiot, W. A., Baker, R., Luchtefeld, M. A., Anthone, G., Schlinkert, R., Roig, J. V., Villoslada, C., Solana, A., Alos, R., Hinojosa, J., Lledo, S., Johnson, D. R. E., Buie, W. D., Jensen, L. L., Heine, J., Hoffmann, B., Timmcke, A., Hicks, T., Opelka, F., Beck, D., Sousa, Jr., A., AraÚjo, S. A., Damico, F. M., Cordeiro, A. C., Pinotti, H. W., Gama, A. H., Fengler, S., Pearl, R., Orsay, C., Seow-Choen, F., Ho, J. M. S., Wiltz, O. H., Torregrosa, M., Brasch, R. C., Bufo, A. J., Krienberg, P., Johnson, G. P., Gowen, G. F., Mullen, P. D., Behrens, D., Hughes, T. G., Wynn, M., Pollack, J. S., Rajagopal, A. S., Huynh, T., Schanbacher, C., Hickson, W. G. E., Yang, Y. -K., Heymen, S., Choi, S. -K., Teoh, T. -A., Wexner, S. D., Vaccaro, C. A., Teoh, T. A., Nogueras, J. J., Choi, S. K., Cheong, D. M. O., Salanga, V. D., MacDonald, A., Baxter, J. N., Finlay, I. G., Mellgren, A., Bremmer, S., Dolk, A., Gillgren, P., Johansson, C., Ahlbäck, S. O., Udén, R., Holmström, B., Ferrara, A., O'Donovan, S., Larach, S. W., Williamson, P. R., Neto, J. A. Reis, Ciquini, S., Quilici, F. A., Reis, Jr., J. A., Torrabadella, L., Salgado, G., Whelan, R. L., Horvath, K. D., Golub, R., Ahsan, H., Cirocco, W., Ziv, Y., Fazio, V. W., Oakley, J. R., Church, J. M., Milsom, J. W., Lavery, L. C., Cohen, S. M., Kmiot, W. A., Reiver, D., Reissman, P., Weiss, E. G., Alós, R., García-Granero, E., Roig, J. V., Uribe, N., Sala, C., Lledo, S., Ozuner, G., Strong, S. A., Bufo, A. J., Daniels, G., Lieberman, R. C., Feldman, S., Lucas, F. V., Longo, W. E., Polites, G., Deshpande, Y., Vernava, A. M., Niehoff, M., Chandel, B., Berglund, D. D., Madoff, R. D., Gemlo, B. T., Spencer, M. P., Goldberg, S. M., Lowry, A. C., Marcello, P. W., Roberts, P. L., Schoetz, D. J., Murray, J. J., Coller, J. A., Veidenheimer, M. C., Koltun, W. A., Bloomer, M. M., Colony, P., Ruggeiro, F., Fleshner, P. R., Michelassi, F., Lewis, W., Williamson, M., Holdsworth, P., Finan, P., Ash, D., Johnston, D., Moran, M. R., Ramos, A., Rothenberger, D. A., Antonenko, D. R., Khanduja, K. S., Fitzgerald, S. D., Meagher, A. P., Moniz-Pereira, P., Wolff, B. G., Outwater, E. K., Marks, G. J., Mohiuddin, M., Sagar, P. M., Hartley, M. N., Mancey-Jones, B., Sedman, P., May, J., MacFie, J., Holbrook, R. F., Rodriguez-Bigas, M. A., Ramakrishnan, K., Palmer, M. L., Petrelli, N. J., Takahashi, T., Nivatvongs, S., Batts, K. P., Lucas, S. W., Klein, S. N., Keidan, R. D., Bannon, J. P., Zhou, J., Armitage, N. C., Hunt, L. M., Robinson, M. H., Hugkulstone, C. E., Clarke, B., Vernon, S. A., Gregson, R. H., Hardcastle, J. D., Ryan, M., Dutta, S., Levine, A., Ortega, A., Anthone, G., Beart, R., Dominguez, J. M., Saclarides, T. J., Bolan, P., Bines, S. D., Adachi, M., Watanabe, T., Sawada, T., Okinaga, K., Muto, T., Hase, K., Shatney, C., Mochizuki, H., Johnson, D., Ure, T., Dehghan, K., Andrus, C. A., Daniel, G. L., D'Emilia, J. C., Rodriguez-Bigas, M., Suh, O. K., Brewer, D. A., Fung, C., Chapuis, P., Bokey, E. L., Garcia, J. C., Banerjee, S., Remzi, F. H., Lavery, I. C., Jorge, J. M. N., Ger, G. C., Gonzalez, L., Gee, A. S., Roe, A. M., Durdey, P., Kaye, M. D., Kyzer, S., Gordon, P. H., Hasegawa, M., Bun, P. Tae, Ikeuchi, D., Onodera, H., Imamura, M., Maetani, S., Blake, T., Hellinger, M., Grewal, H., Klimstra, D. S., Cohen, A. M., Guillem, J. G., Rooney, P. S., Gifford, K. -A., Clarke, P. A., Kuhn, J. A., Bryce, K., Frank, N., Dignan, R. D., Lichliter, W. E., Franko, E., Jacobson, R. M., Preskitt, J. T., Lieberman, Z., Tulanon, P., Steinbach, H., McCarty, T., Simons, T., Plasencia, G., Viamonte, M., Wiltz, O., Jacobs, M., Chen, W. S., Leu, S. Y., Hsu, H., Bessler, M., Halverson, A., Kayton, M. L., Treat, M. R., Nowygrod, R., Congilosi, S., Madoff, R., Wong, W. D., Rothenberger, D., Buie, W. D., Paterson, R., Cartmill, J. A., Trokel, M. J., Gingold, B. S., Cooper, M., Gorfine, S. R., Bauer, J. J., Gelernt, I. M., Kreel, I., Harris, M. T., Vallejo, J. F., Kestenberg, A., Miyajima, N., Kano, N., Ishikawa, Y., Sakai, S., Yamakawa, T., Otchy, D. P., Van Heerden, J. A., Ilstrup, D. M., Weaver, A. L., Winter, L. D., Mav, J., Lee, P. Y., Vetto, J. T., Sullivan, E. S., Rabkin, J., Mayoral, J. L., Matas, A. J., Bove, P., Visser, T., Barkel, D., Villalba, M., Bendick, P., Glover, J., Golub, R. W., Cirocco, W. C., Daniel, N., Altringer, W., Domingues, J. M., Brubaker, L. T., Smith, C. S., Kumar, S., and Gilbert, P.

Published
1994
Full Text
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88. ‘Other’ worlds

Author

Harvey, Francis, primary, Cheesman, Jo, additional, Kitchin, Rob, additional, Daniel Jacobson, R, additional, and Dodge, Martin, additional

Published
2001
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89. Revised Orbits of Saturn's Small Inner Satellites

Author

Jacobson, R. A, Spitale, J, Porco, C. C, Beurle, K, Cooper, N. J, Evans, M. W, and Murray, C. D

Subjects
Astrophysics
Abstract

We have updated the orbits of the small inner Saturnian satellites using additional Cassini imaging observations through 2007 March. Statistically significant changes from previously published values appear in the eccentricities and inclinations of Pan and Daphnis, but only small changes have been found in the estimated orbits of the other satellites. We have also improved our knowledge of the masses of Janus and Epimetheus as a result of their close encounter observed in early 2006.

Published
2007

90. Cassini Orbit Determination Performance during Saturn Satellite Tour: August 2005 - January 2006

Author

Antreasian, Peter G, Bordi, J. J, Criddle, K. E, Ionasescu, R, Jacobson, R. A, Jones, J. B, MacKenzie, R. A, Parcher, D. W, Pelletier, F. J, Roth, D. C, and Stauch, J. R

Subjects
Astronomy
Abstract

During the period spanning the second Enceladus flyby in July 2005 through the eleventh Titan encounter in January 2006, the Cassini spacecraft was successfully navigated through eight close-targeted satellite encounters. Three of these encounters included the 500 km flybys of the icy satellites Hyperion, Dione and Rhea and five targeted flybys of Saturn's largest moon, Titan. This paper will show how our refinements to Saturn's satellite ephemerides have improved orbit determination predictions. These refinements include the mass estimates of Saturn and its satellites by better than 0.5%. Also, it will be shown how this better orbit determination performance has helped to eliminate several statistical maneuvers that were scheduled to clean-up orbit determination and/or maneuver-execution errors.

Published
2007

97. Use of Very Long Baseline Array Interferometric Data for Spacecraft Navigation

Author

Martin-Mur, Tomas J, Antreasian, P, Border, J, Benson, J, Dhawan, V, Fomalont, E, Graat, E, Jacobson, R, Lanyi, G, McElrath, T, Romney, J, and Walker, C

Subjects
Space Communications, Spacecraft Communications, Command And Tracking
Abstract

The main VLBI technique that is used at JPL is known as the Delta Differential One-way Ranging ((Delta)DOR). Two DSN antennas simultaneously track a source, and alternate between sources. The signals recorded at the antennas from each source are correlated to obtain the delay in arrival to the two antennas, and the delays are differenced to remove common-source errors. An alternative technique is to use carrier phase differences between antennas. This is routinely done by the Very Large Baseline Array (VLBA) as part of source imaging. The VLBA capabilities are used for scientific research, but also have the potential to be used for navigation. Two main experiments were performed with the VLBA and JPL spacecraft. This paper describes and analyzes these experiments and discusses the possible uses of VLBA tracking for spacecraft navigation.

Published
2006

98. Atmospheric drag model for Cassini orbit determination during low altitude Titan flybys

Author

Pelletier, F. J, Antreasian, P. G, Bordi, J. J, Criddle, K. E, Ionasescu, R, Jacobson, R. A, Mackenzie, R. A, Parcher, D. W, and Stauch, J. R

Subjects
Astrodynamics
Abstract

On April 16, 2005, the Cassini spacecraft performed its lowest altitude flyby of Titan to date, the Titan-5 flyby, flying 1027 km above the surface of Titan. This document discusses the development of a Titan atmospheric drag model for the purpose of the orbit determination of Cassini. Results will be presented for the Titan A flyby, the Titan-5 flyby as well as the most recent low altitude Titan flyby, Titan-7. Different solutions will be compared against OD performance in terms of the flyby B-plane parameters, spacecraft thrusting activity and drag estimates. These low altitude Titan flybys were an excellent opportunity to observe the effect of Titan's atmospheric drag on the orbit determination solution and results show that the drag was successfully modeled to provide accurate flyby solutions.

Published
2006

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