Light to Sound: The Remote Acoustic Sensing Satellite (RASSat)

“In space, no one can hear you scream,” as the tagline from the sci-fi film Aliens goes. But what if there were a way of “hearing” in space, moving in-space video from the Silent Era to a more contemporary cinematic experience? How could this capability be applied to shape future spacecraft and mission designs? Such a capability can be effectively incorporated into a 3U CubeSat using a measurement technique called Remote Acoustic Sensing (RAS). “RASSat” uses advanced optical sensors to view and recover audio from distant objects that have weak optical modulations produced by local sound and vibration sources; the modulated light sources and the RAS sensor are passively coupled at the speed of light, yielding a variety of interesting sounds across the entire human auditory range. RAS field demonstrations and analyses have identified and characterized terrestrial sound sources observable from LEO, along with associated acousto-optic modulation mechanisms. RASSat sensitivity is such that both day and night strong, easily detectable terrestrial acousto-optic emitters abound, and applications to Space Situational Awareness and planetary exploration are also evident. This paper provides an overview of the RAS measurement technique and recent terrestrial demonstrations, and highlights key RASSat design features, performance capabilities and applications