  The farside of the Moon is a pristine, quiet platform to conduct low radio
frequency observations of the early Universe's Dark Ages, as well as space
weather and magnetospheres associated with habitable exoplanets. In this paper,
the astrophysics associated with NASA-funded concept studies will be described
including a lunar-orbiting spacecraft, DAPPER, that will measure the 21 cm
global spectrum at redshifts 40-80, and an array of low frequency dipoles on
the lunar farside surface, FARSIDE, that would detect exoplanet magnetic
fields. DAPPER observations (17-38 MHz), using a single cross-dipole antenna,
will measure the amplitude of the 21 cm spectrum to the level required to
distinguish the standard {\Lambda}CDM cosmological model from those of
additional cooling models possibly produced by exotic physics such as dark
matter interactions. FARSIDE has a notional architecture consisting of 128
dipole antennas deployed across a 10 km area by a rover. FARSIDE would image
the entire sky each minute in 1400 channels over 0.1-40 MHz. This would enable
monitoring of the nearest stellar systems for the radio signatures of coronal
mass ejections and energetic particle events, and would also detect the
magnetospheres of the nearest candidate habitable exoplanets. In addition,
FARSIDE would determine the Dark Ages global 21 cm signal at yet lower
frequencies and provide a pathfinder for power spectrum measurements.
