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A suite of three optical instruments has been developed to observe Comet 9P/Tempel 1, the impact of a dedicated impactor spacecraft, and the resulting crater formation for the Deep Impact mission. The high-resolution instrument (HRI) consists of an f/35 telescope with 10.5mfocal length, and a combined filtered CCD camera and IR spectrometer. The medium-resolution instrument (MRI) consists of an f/17...
Comet 67P/Churyumov-Gerasimenko was observed with the International Ultraviolet Explorer (IUE) satellite observatory on 7 November 1982, five days before perihelion. At the time of the observation the heliocentric distance was 1.307 AU and the geocentric distance 0.414 AU. Only two relatively short exposures were obtained, one each with the short (SWP) and long wavelength (LWR) cameras. In the LWR...
The Deep Impact mission revealed many properties of comet Tempel 1, a typical comet from the Jupiter family in so far as any comet can be considered typical. In addition to the properties revealed by the impact itself, numerous properties were also discovered from observations prior to the impact just because they were the types of observations that had never been made before. The impact showed that...
The science payload on the Deep Impact mission includes a 1.05–4.8µm infrared spectrometer with a spectral resolution ranging from R ∼ 200–900. The Deep Impact IR spectrometer was designed to optimize, within engineering and cost constraints, observations of the dust, gas, and nucleus of 9P/Tempel 1. The wavelength range includes absorption and emission features from ices, silicates, organics, and...
In 1998, Comet 9P/Tempel 1 was chosen as the target of the Deep Impact mission (A’Hearn, M. F., Belton, M. J. S., and Delamere, A., Space Sci. Rev., 2005) even though very little was known about its physical properties. Efforts were immediately begun to improve this situation by the Deep Impact Science Team leading to the founding of a worldwide observing campaign (Meech et al., Space Sci. Rev., 2005a)...
The Deep Impact mission will provide the first data on the interior of a cometary nucleus and a comparison of those data with data on the surface. Two spacecraft, an impactor and a flyby spacecraft, will arrive at comet 9P/Tempel 1 on 4 July 2005 to create and observe the formation and final properties of a large crater that is predicted to be approximately 30-m deep with the dimensions of a football...
The Deep Impact mission will provide the highest resolution images yet of a comet nucleus. Our knowledge of the makeup and structure of cometary nuclei, and the processes shaping their surfaces, is extremely limited, thus use of the Deep Impact data to show the geological context of the cratering experiment is crucial. This article briefly discusses some of the geological issues of cometary nuclei.
We analyzed Deep Impact High Resolution Instrument (HRI) images acquired within the first seconds after collision of the Deep Impact impactor with the nucleus of comet 9P/Tempel 1. These images reveal an optically thick ejecta plume that casts a shadow on the surface of the nucleus. Using the 3D radiative transfer code HYPERION we simulated light scattering by the ejecta plume, taking into account...
On November 4th, 2010, the Deep Impact eXtended Investigation (DIXI) successfully encountered comet 103P/Hartley 2, when it was at a heliocentric distance of 1.06AU. Spatially resolved near-IR spectra of comet Hartley 2 were acquired in the 1.05–4.83μm wavelength range using the HRI-IR spectrometer. We present spectral maps of the inner ∼10km of the coma collected 7min and 23min after closest approach...
We present an analysis of comet activity based on the Spitzer Space Telescope component of the Survey of the Ensemble Physical Properties of Cometary Nuclei. We show that the survey is well suited to measuring the activity of Jupiter-family comets at 3–7AU from the Sun. Dust was detected in 33 of 89 targets (37±6%), and we conclude that 21 comets (24±5%) have morphologies that suggest ongoing or recent...
Re-calibrated near-infrared spectroscopy of the resolved nucleus of Comet 9P/Tempel 1 acquired by the Deep Impact spacecraft has been analyzed by utilizing the post-Stardust-NExT nucleus shape model and spin pole solution, as well as a novel thermophysical model that explicitly accounts for small-scale surface roughness and thermal inertia. We find that the thermal inertia varies measurably across...
We present high-resolution infrared spectroscopic measurements of the ecliptic Comet 2P/Encke, observed on 4–6 November 2003 during its close approach to the Earth, using the Near Infrared Echelle Spectrograph on the Keck II telescope. We present flux-calibrated spectra, production rates, and mixing ratios for H 2 O, CH 3 OH, HCN, H 2 CO, C 2 H 2 , C 2 ...
The EPOXI mission flyby of Comet 103P/Hartley 2 revealed numerous discrete dust jets extending from the nucleus, thereby providing an unprecedented opportunity to visually connect these features to the nuclear surface. The observed distribution of jets yields fresh insight into the conditions under which these cometary features may form. This study examines the geomorphology associated with areas...
We derive the spin state of the nucleus of Comet 103P/Hartley 2, its orientation in space, and its short-term temporal evolution from a mixture of observations taken from the DIXI (Deep Impact Extended Investigation) spacecraft and radar observations. The nucleus is found to spin in an excited long-axis mode (LAM) with its rotational angular momentum per unit mass, M, and rotational energy per unit...
The Deep Impact Spacecraft flew past Comet 103P/Hartley 2 on November 4th, 2010. Images revealed the comet to be enveloped in a field of debris composed of fine grained dust, ice, and hundreds of discrete millimeter to decimeter sized particles. In this work, a selection of the brightest particles are identified and photogrammetrically located in 3D space to examine their positions and dynamics. 90%...
A flaw in the pre-launch calibration system resulted in an inability to accurately focus the Deep Impact’s High Resolution Instrument (HRI). This defocus resulted in a significant loss of resolution. The nature of the blurring function allows us to use image restoration techniques to retrieve much of the lost resolution. These techniques can produce artifacts in the image such as noise amplification...
We have studied the photometric properties of the nucleus of a hyperactive comet, 103P/Hartley 2, at visible wavelengths using the DIXI flyby images with both disk-integrated and disk-resolved analyses. The disk-integrated phase function of the nucleus has a linear slope of 0.046±0.002mag/deg and an absolute magnitude of 18.4±0.1 at V-band. The nucleus displays an overall linear, featureless spectrum...
We consider the origin of ∼380 quasi-circular depressions (pits) seen to be distributed in a broad band across the surface of 9P/Tempel 1 and show that possibly ∼96% may be due to outburst activity. Of the rest, <4%, are probably due to a mix of cryo-volcanic collapse events and collisional impacts with asteroidal material. We estimate the mass ejected during the June 14, 2005, mini-outburst on...
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