Dennis Wellnitz

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Deep Impact collided with comet Tempel 1, excavating a crater controlled by gravity. The comet's outer layer is composed of 1- to 100-micrometer fine particles with negligible strength (<65 pascals). Local gravitational field and average nucleus density (600 kilograms per cubic meter) are estimated from ejecta fallback. Initial ejecta were hot (>1000(More)
The goal of the work described in this paper is to design and build a scalable infrastructure for executing grid applications on a widely distributed set of resources. Such grid infrastructure must be decentralized, robust, highly available, and scalable, while efficiently mapping application instances to available resources in the system. However, current(More)
The EPOXI Discovery Mission of Opportunity reused the Deep Impact flyby spacecraft to obtain spatially and temporally resolved visible photometric and moderate resolution near-infrared (NIR) spectroscopic observations of Earth. These remote observations provide a rigorous validation of whole-disk Earth model simulations used to better understand remotely(More)
Izenberg, S. L. Murchie, J. F. Bell III , L. A. McFadden, D. D. Wellnitz, B. E. Clark, and M. J. Gaffey, The Johns Hopkins University Applied Physics Laboratory, 11100 Johns Hopkins Road, Laurel, Maryland 20723, USA, noam.Izenberg@jhuapl.edu, Cornell University, Center for Radiophysics and Space Research, University of Maryland, Astronomy Department, Ithaca(More)
Deep Impact images of the nucleus of Comet Tempel 1 reveal pervasive layering, possible impact craters, flows with smooth upper surfaces, and erosional stripping of material. There are at least 3 layers 50–200 m thick that appear to extend deep into the nucleus, and several layers 1–20 m thick that parallel the surface and are being eroded laterally.(More)
On 25 October 2000, the Near Earth Asteroid Rendevous (NEAR)-Shoemaker spacecraft executed a low-altitude flyover of asteroid 433 Eros, making it possible to image the surface at a resolution of about 1 meter per pixel. The images reveal an evolved surface distinguished by an abundance of ejecta blocks, a dearth of small craters, and smooth material(More)
From February 13 to May 13, 2000, the Near Infrared Spectrometer (NIS) instrument on the Near Earth Asteroid Rendezvous (NEAR) mission obtained more than 200,000 spatially-resolved 800 to 2500 nm reflectance spectra of the S-type asteroid 433 Eros. An important subset of the spectra were obtained during a unique opportunity on February 13 and 14, when the(More)
Return to Comet Tempel 1: Overview of Stardust-NExT results J. Veverka a,⇑, K. Klaasen , M. A’Hearn , M. Belton , D. Brownlee , S. Chesley , B. Clark , T. Economou , R. Farquhar , S.F. Green , O. Groussin , A. Harris , J. Kissel , J.-Y. Li , K. Meech, J. Melosh , J. Richardson , P. Schultz , J. Silen , J. Sunshine , P. Thomas , S. Bhaskaran , D. Bodewits ,(More)
We discuss the properties of the nucleus and inner coma of Comet Hale–Bopp (C/1995 O1) as derived from observations of its occultation of Star PPM 200723 on 5 October 1996, while the comet was 2.83 AU from the Sun. Compared to previous occultations by active comets, this is possibly the closest to the nucleus one has ever observed. Three chords(More)