  We make the case for the early development of a Mid-Frequency-Band (MFB)
gravitational wave (GW) observatory in geosynchronous orbit (73,000 km arm),
optimized for the frequency band 10 mHz to 1 Hz. MFB bridges the science
acquisition frequencies between the ground observatories LIGO/VIRGO (4/3 km arm
- as well as future planned ones 10/40 km arm), and the milli-hertz band of
LISA (2.5 Gm arm)- with usable sensitivity extending to 10 Hz. We argue that
this band will enable the timely development of this game-changing field of
astrophysics, with observations of medium mass Binary Black Holes (BBH) and
Binary Neutron Stars (BNS) sources prior to their mergers in the LIGO frequency
range as well as Extreme Mass Ratio Inspirals (EMRI)s and mergers of
supermassive BBH within the main detection band. MFB is better placed than LISA
to access this exciting frequency region.
