  We report on studies of the viability and sensitivity of the Askaryan Radio
Array (ARA), a new initiative to develop a Teraton-scale ultra-high energy
neutrino detector in deep, radio-transparent ice near Amundsen-Scott station at
the South Pole. An initial prototype ARA detector system was installed in
January 2011, and has been operating continuously since then. We report on
studies of the background radio noise levels, the radio clarity of the ice, and
the estimated sensitivity of the planned ARA array given these results, based
on the first five months of operation. Anthropogenic radio interference in the
vicinity of the South Pole currently leads to a few-percent loss of data, but
no overall effect on the background noise levels, which are dominated by the
thermal noise floor of the cold polar ice, and galactic noise at lower
frequencies. We have also successfully detected signals originating from a 2.5
km deep impulse generator at a distance of over 3 km from our prototype
detector, confirming prior estimates of kilometer-scale attenuation lengths for
cold polar ice. These are also the first such measurements for propagation over
such large slant distances in ice. Based on these data, ARA-37, the 200 km^2
array now under construction, will achieve the highest sensitivity of any
planned or existing neutrino detector in the 10^{16}-10^{19} eV energy range.
