Asteroid space weathering

Clark, B.E., Hapke, B., Pieters, C. and Britt, D. (2002) Asteroid space weathering and regolith evolution. In Asteroids HI, eds. Bottke, W. E, Cellino, A., Paolicchi, P. and Binzel, R. P. Tucson University of Arizona Press, pp. 585-602. 

Hapke B (2001) Space weathering from Mercury to die asteroid belt. J Geophys Res 106 10039-10073 Hapke B, Cassidy W, Wells E (1994) Vqior deposits in die lunar regolidi Technical comment. Science 264 1779... 

Many asteroid spectra tend to be "redder" than the spectra of the corresponding meteorites. Reddened spectra have lower reflectivity, weaker absorptions, and spectral slopes that are flatter in the red end. This phenomenon has been attributed to "space weathering," a catchall term referring to any process that modifies the optical properties of surfaces of airless bodies exposed to the space environment. 

Comparison of the spectra of asteroid 4 Vesta and the eucrite Jonzac. The subdued and reddened spectra of Vesta suggest space weathering. Modified from Clark et al. (2002). 

The first experiments with the thermal electric engine were conducted in Russia in 1929 by its inventor, Valentin P. Glushko, who later became a world-famous authority in rocket propulsion. For more than forty years, the United States and Russia have devoted many resources to research and development of various kinds of EREs. First tested in space by the Russians in 1964, these engines have found some limited applications in modern space technology. For more than two decades Russian weather and communication satellites have regularly used electric rocket engines for orbital stabilization. The first spacecraft to employ ERE for main propulsion was the American asteroid exploration probe Deep Space 1, launched in 1998. The performance of... 

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