Direct detection of Earth-like magnetic fields with GO-LoW: the Great Observatory for Long Wavelengths

Humankind has never before seen the low frequency radio sky. That sky is expected to teem with exoplanet radio aurorae between ~1-10 MHz, but the Earth’s ionosphere is opaque to this frequency range. We present the Great Observatory for Long Wavelengths (GO-LoW), an ambitious constellation telescope designed with exoplanet and stellar magnetic fields as the primary science drivers. Of the thousands of exoplanets that have been discovered in the last 20 years, many are expected to produce powerful auroral radio emissions from star-planet interactions and internal magnetospheric processes. These aurorae characterize planetary magnetic fields across the full range of planet mass and orbital distance and will drive major advancements in exoplanet science by: 1) Enabling statistical studies of the relationship between planet properties and magnetic fields, for which the Solar System planets alone do not provide a large enough sample. 2) Directly testing magnetic field predictions from exoplanet dynamo models, and constraining exoplanet interior structure/composition needed to sustain the dynamo field. 3) Broadening the study of exo-auroral physics, a young field that currently relies on brown dwarfs as test beds. 4) Providing inputs into exoplanet atmospheric evolution and high energy radiation modeling, informing habitability and astrobiology studies. Adding a space-based capability to observe planetary radio emissions to the existing toolbox of infrared, optical, ultraviolet, and X-ray imaging and spectroscopy is essential. We present the results of a NASA-funded NIAC Phase I concept study of GO-LoW, a space-based interferometric radio telescope composed of thousands of small satellites at the L4/L5 Earth-Sun Lagrange point. GO-LoW proposes to detect and characterize exoplanetary magnetic fields within ~5 pc of the solar system via auroral radio emission. This free-flying array is optimized for 300 kHz-15 MHz. Concept study results include science requirements, mission architecture, correlation and communication design, and a technology roadmap required to achieve this ambitious mission which will revolutionize our understanding of exoplanet magnetic fields.