In studying technological change, we often seek to understand the dynamics of how technologies and practice shape each other over time, examining sites of innovation, adaptation, and appropriation, of making and re-making systems anew. However less attention has been given to how formerly cutting-edge technologies become old, how people work alongside aging and obsolescent systems, or how organizations prepare for the end of a technology's life cycle. In this dissertation, I argue that this bias towards progressivist accounts of technological change obscures the "lived" temporal relations of systems work. I present research drawn from ten months of ethnographic fieldwork with engineers at the Cassini mission to Saturn, at the Jet Propulsion Laboratory, in Pasadena, CA. Having launched in 1997, the longevity of the mission means that their work takes place in the context of an aging spacecraft and increasingly obsolescent software infrastructure. As the mission is bound to complete in 2017, engineers are beginning to plan for and work towards the end of the mission and reflect on its origins and possible legacies. Cassini thus offers a perspicuous case for understanding technological change. I examine how Cassini's computational infrastructure mediates the work of translating across multiple temporal concerns--from multi-year science objectives to the run time of algorithms to the lifetimes and legacies of hardware and software tools. In doing so, I shift attention from understanding how technologies emerge in practice, to how people live with technological change at the duration of lived experience. I articulate a lens that reveals technological change not as a single phenomenon belonging to a totalized system (e.g., the organizational infrastructure, information ecology, or sociotechnical system) but rather as multiple modes or regimes among which people, and organizations, evaluate how technologies (ought to) develop over time. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]