“Ephemeral Afterimage” is an extension of our ongoing Earth-Moon-Earth radio transmission project “Librations”, exploring the physicality and materiality of the sonorous and electromagnetic signals with which we work. Through conducting EME signal ‘moonbounces,’ “Librations” repurposes technology to propose new understandings of our situatedness within nested dimensions at the planetary scale, and the potential for a poetic, affective, and spectral commons. As an extension of this, “Ephemeral Afterimage” takes a recorded echo of the artists’ own reflected voices and mechanically transcribes it upon the surface of a black sphere. To produce this transcription, the recording is played back through a specialized speaker membrane with an affixed stylus, which kinetically traces the frequency and amplitude profile of our voices across the rotating sphere. Sourcing in part from the tradition of the phonautograph (the first sonic recording medium), this project seeks to extend the traditions of tracing sonic materiality through its inscription in various mediums. The sphere and the etching which encircles it archives one signal’s journey from the Earth to the Moon and back again, wherein the signal’s information and its accrued interferences and artifacts are combined/expressed into a continuous flowing line. As such, this project iteration stands as a part of a broader media study concerned with transmission and translation, tracing both the physicality and dynamism of a signal’s state-change to and from the acoustic and electromagnetic axes, to its physical etching upon a material object.