In practice, vaporization is .... law applies (emittance = absorbance). The cometary emis- ..... the sample, and particles were collected over a large sam- pling area. ..... for their identification during vaporization (e.g., Bernstein et al., 1995). 4.2.
Colangeli et al.: Laboratory Experiments on Cometary Materials
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Laboratory Experiments on Cometary Materials L. Colangeli and J. R. Brucato Istituto Nazionale di Astrofisica–Osservatorio Astronomico di Capodimonte
A. Bar-Nun Tel Aviv University
R. L. Hudson Eckerd College and NASA Goddard Space Flight Center
M. H. Moore NASA Goddard Space Flight Center
Laboratory experiments to simulate cometary materials and their processing contribute to the investigation of the properties and evolution of comets. Experimental methods can produce both refractory materials and frozen volatiles with chemical, structural, and morphological characteristics that reproduce those of materials observed and/or expected in comets. Systematic analyses of such samples, before and after energetic processing by various agents effective in the solar system, provide a wealth of useful quantitative information. Such data permit a more complete interpretation of observations, performed remotely or in situ, and suggest ideas about the chemical and physical evolution of cometary dust and ice. Finally, laboratory results help to predict the environmental conditions that future space missions, such as the European Space Agency’s Rosetta mission, will experience, and thus aid in properly planning mission and instrument development.
1.
INTRODUCTION
Comets are considered to be reservoirs of partially uncontaminated primordial material from which the solar system formed about 4.5 × 109 yr ago. The composition as well as the physical and structural properties of cometary dust and ice depend both on comet formation mechanisms and postaccretion evolutionary processes. The so-called “interstellar grain” model (e.g., Greenberg and Hage, 1990; Mumma, 1997; Notesco et al., 2003) supports the concept that comets formed far (>20 AU) from the proto-Sun, at low temperatures (
