PoZoLE: A Tiny Space Telescope to Snap our Solar System’s Ultraviolet Selfie

The zodiacal cloud is our solar system’s biggest structure visible to the unaided eye, yet its constituent dust particles’ origins are controversial, with a wide range of proposed divisions between sources in the asteroids and Jupiter Family comets. Furthermore, any contribution from Oort Cloud comets is poorly constrained. The zodiacal cloud gains new meaning with the Astro2020 Decadal Survey recommending that NASA develop a large space telescope to characterize potentially Earth-like planets around nearby stars. The large telescope will seek signs of oxygen in the atmospheres of exo-Earths by the Hartley absorption band of ozone in the near-ultraviolet — the same absorption that helps protect us on the Earth’s surface from sunburn. However, the exo-Earths and their ozone may be obscured by the host stars’ light scattered from their extrasolar analogs of our zodiacal cloud. As the only such cloud where the source bodies can be tracked, our own interplanetary dust is a key to learning how the system architecture governs the cloud’s appearance. We therefore propose launching a tiny space telescope in a 6U cubesat to return a selfie showing our solar system’s dust from the outside in the near-UV. Self-knowledge is power! Here, it will enable designing a large telescope to best pick out an Earth analog against a dust cloud like our own.

The key to turning observations from Earth orbit into a view of our zodiacal cloud from the outside is to measure the polarization of the sunlight scattered from the cloud’s dust particles. The tiny telescope is therefore named the Polarized Zodiacal Light Experiment, or PoZoLE, after a delicious soup. We use PoZoLE’s planned capabilities to “observe” the modeled near-UV appearance of a proposed structure for the zodiacal cloud against a synthetic Milky Way background, and show the measurements are sufficient to determine the cloud’s shape and size, construct a selfie, and estimate how much of the UV-scattering dust comes from each source family: asteroids, Jupiter Family comets, and Oort Cloud comets, with their differing orbits. PoZoLE employs space-ready technologies and can be built within the $20M cost cap of NASA’s Astrophysics Pioneers program, while engaging the next generation of scientists and engineers in solving a problem that is central to astrophysics at NASA.