  We initiate the study of gravitational wave (GW) signals from first-order
phase transitions in supersymmetry-breaking hidden sectors. Such phase
transitions often occur along a pseudo-flat direction universally related to
supersymmetry (SUSY) breaking in hidden sectors that spontaneously break
$R$-symmetry. The potential along this pseudo-flat direction imbues the phase
transition with a number of novel properties, including a nucleation
temperature well below the scale of heavy states (such that the temperature
dependence is captured by the low-temperature expansion) and significant
friction induced by the same heavy states as they pass through bubble walls. In
low-energy SUSY-breaking hidden sectors, the frequency of the GW signal arising
from such a phase transition is guaranteed to lie within the reach of future
interferometers given existing cosmological constraints on the gravitino
abundance. Once a mediation scheme is specified, the frequency of the GW peak
correlates with the superpartner spectrum. Current bounds on supersymmetry are
compatible with GW signals at future interferometers, while the observation of
a GW signal from a SUSY-breaking hidden sector would imply superpartners within
reach of future colliders.
