  FarView is an early-stage concept for a large, low-frequency radio
observatory, manufactured in-situ on the lunar far side using metals extracted
from the lunar regolith. It consists of 100,000 dipole antennas in compact
subarrays distributed over a large area but with empty space between subarrays
in a core-halo structure. FarView covers a total area of ~200 km2, has a dense
core within the inner ~36 km2, and a ~power-law falloff of antenna density out
to ~14 km from the center. With this design, it is relatively easy to identify
multiple viable build sites on the lunar far side. The science case for FarView
emphasizes the unique capabilities to probe the unexplored Cosmic Dark Ages -
identified by the 2020 Astrophysics Decadal Survey as the discovery area for
cosmology. FarView will deliver power spectra and tomographic maps tracing the
evolution of the Universe from before the birth of the first stars to the
beginning of Cosmic Dawn, and potentially provide unique insights into dark
matter, early dark energy, neutrino masses, and the physics of inflation. What
makes FarView feasible and affordable in the timeframe of the 2030s is that it
is manufactured in-situ, utilizing space industrial technologies. This in-situ
manufacturing architecture utilizes Earth-built equipment that is transported
to the lunar surface to extract metals from the regolith and will use those
metals to manufacture most of the array components: dipole antennas, power
lines, and silicon solar cell power systems. This approach also enables a long
functional lifetime, by permitting servicing and repair of the observatory. The
full 100,000 dipole FarView observatory will take 4 - 8 years to build,
depending on the realized performance of the manufacturing elements and the
lunar delivery scenario.
