September 7, 2006 issue of "Nature" (vol. 443 pages 56-58).
Entitled "Developing Space Weathering on the Asteroid 25143 Itokawa", the paper is about work that Clark completed during a leave of absence in the Fall of 2005. Clark was one of ~12 NASA asteroid scientists invited to Tokyo Japan last fall to participate in the operations phase of the "Hayabusa" spacecraft mission to sample an asteroid. The mission was operated from a campus of the Japanese Aerospace Exploration Agency (JAXA). The orbital phase of the mission was highly successful, resulting in downlink of several GBytes of imaging and spectroscopic data. If the sampling attempt was similarly successful, mission scientists will open the sample container in June 2010 to find the first rocks ever returned from an asteroid surface.
https://www.ithaca.edu/intercom/article.php/20060926162558202