WASHINGTON (Reuters) - NASA (news - web sites) needs high-resolution pictures of the external fuel tanks that boost shuttles into orbit, and these images should be taken during any future launch and ascent, investigators probing the Columbia disaster said Wednesday. The Columbia Accident Investigation Board said these sharp images, made available to ground controllers soon after the external tank separates from the orbiter after launch, would help engineers troubleshoot any problems during shuttle missions. "Imaging the space shuttle system during launch and ascent provides necessary engineering data including the ability to examine the space shuttle system for any unexpected debris...