The FarView Low Frequency Radio Array on the Moon's Far Side: Science and Array Architecture

TL;DR

FarView is a proposed lunar far side low frequency radio array designed to study the Cosmic Dark Ages and other astrophysical phenomena, leveraging the Moon's radio quiet environment for groundbreaking cosmological and space weather research.

Contribution

This paper introduces the design and science case for FarView, a large-scale lunar radio array enabling unprecedented observations of the early universe and space weather phenomena.

Findings

Forecasts a 10-sigma detection of the Dark Ages 21 cm power spectrum at z=30.

Design features 100,000 antennas in a dense core-halo configuration over 200 sq km.

Identifies FFT-based EPIC beamformer as an efficient signal processing architecture.

Abstract

FarView is a proposed low frequency radio interferometer for deployment on the lunar far side, enabled by the Moon's radio quiet environment. Operating over 1-50 MHz inaccessible from Earth, FarView will open a new observational window and promote discovery class science in cosmology, heliophysics, Galactic and exoplanet astrophysics. The primary science is measurement of the redshifted 21 cm signal from the Cosmic Dark Ages (z=30-100), identified by the Astro2020 Decadal Survey as a priority cosmology discovery area. FarView will deliver 3D tomographic measurements and precision power spectra of neutral hydrogen in a largely linear regime, enabling tests of inflationary initial conditions, primordial non Gaussianity, dark matter properties, neutrino masses, and early dark energy. The reference design consists of 100000 crossed dipole antennas in a dense core-halo configuration spanning 200 sq km. A compact 4 km core with 83000 dipoles maximizes sensitivity to large scale cosmological modes, while 20000 halo elements extending to 14 km provide angular resolution and calibration for foreground characterization. Sensitivity forecasts indicate a 10-sigma detection of the Dark Ages 21 cm power spectrum at z=30 over five years of half duty cycle lunar night observations. An FFT-based EPIC beamformer is identified as an efficient signal processing architecture. Beyond cosmology, FarView will enable interferometric imaging of low frequency solar radio bursts, advancing space weather studies. Additional capabilities include stellar space weather observations, Galactic cosmic ray tomography via free-free absorption, and searches for auroral radio emission from exoplanet magnetospheres, a probe of exoplanet habitability. FarView represents a flagship class opportunity to establish the Moon as a platform for foundational astrophysics while delivering unique observational capabilities.