  We experimentally investigate Andreev transport through a single junction
between an s-wave indium superconductor and a thick film of a three-dimensional
$Bi_2Te_3$ topological insulator. We study $Bi_2Te_3$ samples with different
bulk and surface characteristics, where the presence of a topological surface
state is confirmed by direct ARPES measurements. All the junctions demonstrate
Andreev transport within the superconducting gap. For junctions with
transparent $In-Bi_2Te_3$ interfaces we find a number of nearly periodic
conductance oscillations, which are accompanied by zero-bias conductance
anomaly. Both effects disappear above the superconducting transition or for
resistive junctions. We propose a consistent interpretation of both effects as
originating from proximity-induced superconducting correlations within the
$Bi_2Te_3$ topological surface state.
