  It may soon be possible for Advanced LIGO to detect hundreds of binary black
hole mergers per year. We show how the accumulation of many such measurements
will allow for the detection of gravitational-wave memory: a permanent
displacement of spacetime that comes from strong-field, general relativistic
effects. We estimate that Advanced LIGO operating at design sensitivity may be
able to make a signal-to-noise ratio 3(5) detection of memory with ~35 (90)
events with masses and distance similar to GW150914. We highlight the
importance of incorporating higher-order gravitational-wave modes for parameter
estimation of binary black hole mergers, and describe how our methods can also
be used to detect higher-order modes themselves before Advanced LIGO reaches
design sensitivity.
