The Polarized Ultraviolet Field From Interstellar Nuclei Survey (PUFFINS) is a NASA Pioneer-class mission dedicated to studying the ultraviolet (UV) polarization of starlight caused by dust grains in the interstellar medium. PUFFINS is planned for launch in 2030.

The main science goal of PUFFINS is to study how tiny dust grains in space interact with ultraviolet light and how they become aligned with the magnetic field of the interstellar medium. PUFFINS will observe the polarization and spectrum of starlight in the wavelength range of approximately 1800–3000 Å, using a spectro-polarimeter with a resolving power of about R = 100.

PUFFINS will at least triple the currently observed sample and will use carefully selected targets to investigate important questions raised by the earlier observations.

·  Why is ultraviolet polarization significantly stronger than expected from optical measurements for some stars?

·  Why is the 2175 Å extinction feature generally unpolarized, while clear polarization is observed along some lines of sight?

·  What do these effects reveal about the properties and alignment of interstellar dust grains?

The mission will build on the Radiative Alignment Torques (RATs) theory, which provides a framework for understanding how dust grains can become aligned by radiation and magnetic fields. The observations will help improve our understanding of the small dust grains and their role in the interstellar medium.

PUFFINS is built under the leadership of the University of Arizona. The IWF plans to lead the exoplanet science case of the mission, provide the data simulator, the data reduction pipeline and support the development of exposure time calculator.

Detailed information can be found at the mission website.