Over the course of the last half-century, humankind has expanded its material and virtual presence beyond Earth's atmosphere and into the unruly borderlands of orbital space. My work traces the construction of a built environment in Earth orbit and the ways in which human beings understand and visualize a space that has been widely used but rarely encountered by the majority of its users. I focus especially on how the growing quantity of "space junk"—any human-made orbiting object that does not serve a specific function—disrupts the largely discursive boundary between earthly and extraterrestrial environments, reinforces material practices of technological imperialism, and challenges terrestrial definitions of ownership, nationality, and responsibility in the face of remote environmental crisis.