This Science and Society Dissertation Improvement Grant will analyze the use of digital images in contemporary planetary astronomy, paying attention to researchers' individual and collaborative interactions with images and imaged objects. Through fieldwork with the Mars Exploration Rover (MER) team, the research will develop a detailed case study of how images are used to develop scientific conclusions, and to operate the Rover at a distance. Of specific interest is how the Rover team uses images to make Mars visible and legible, and how these visualizations inform the researchers' inferences about the planet. The project thus constitutes a practice-based approach to questions of visual epistemology in the context of contemporary space exploration: that is, it focuses on the social and technical achievement of knowledge-making about Mars based on visual representations of its surface. Drawing on fieldwork with the MER team at Cornell University, and visits to other MER sites in California, Arizona and Missouri, this project will address several aspects of image analysis in the Rover project. Participant-observation data will be collected at daily group image dissection activities which are essential to the mission: meetings between engineers and operations managers to decide what the Rovers are 'looking at' and what, based on the visual evidence, they should do next; and discussions among scientists which determine whether or not an image constitutes pictorial evidence that there was once water on Mars. Situating the Rovers within a larger historical context of Martian imaging and imagining, the project will explore how raw images become trustworthy and evidentiary, probe the disciplinary and disciplining activity of astronomical image processing, and discuss the development of the Rover's software tools with respect to the visual languages and conventions of the interdisciplinary research team. Throughout, the dissertation will develop and employ an analytical framework for analyzing theory- and practice-laden representation in science, and explore the theme of visual objectivity as it is managed through digital tools. NSF funding will support ethnographic field work, interviews, and archival work at Cornell, the Jet Propulsion Laboratory in Pasadena, California, and satellite Rover laboratories, test sites, and image processing centers in Arizona and Missouri. The intellectual merit of the project is in its contribution to the study of images in science. It specifically addresses the problem of digital objectivity: the epistemic, practical and moral management of images that is simultaneously diagrammatic and pictorial, manipulated and mechanically produced. Further, it brings tools from social construction of science and technology programs into the virtual sphere, unpacking software suites as social constructions and exploring such STS concepts as inscriptions, immutable mobiles, and the externalized retina in the context of digital image processing. Finally, the analysis of theory laden representation also possesses broad potential application to other social and historical studies of images in science. Beyond the Social Studies of Science, however, the project has a broader impact. As twenty-first century 'big science', the Rovers are plugged into an outreach network involving scientists, schools and legislators. Images play a central role in this network of exchange and thus deserve close and careful scrutiny as instruments of public opinion, knowledge, and funding strategies. Close ethnographic attention to collaboration over distant networks by means of visual technologies may also reveal insights for future technological developments in Computer-Supported Co-operative Work. Finally, the Rover mission is a project of historic significance: the careful documentation and analysis of daily interactions around its images as essential, yet ephemeral, digital artifacts presents a strong contribution to a developing history of the early digital era.