We describe the Long Wavelength Array (LWA), a ground-based radio interferometer capable of serving as a coronal mass ejection (CME) detector. Previous low-frequency (nu < 50 MHz) coronal sounding experiments have shown that CMEs exhibit large radar cross sections. The LWA will serve as the imaging receiver for a bi-static radar observatory that will open an entirely new field of CME research. Because the LWA will be a synthesis interferometer, it will be capable of imaging the return echo as well as measuring its Doppler shift. The combination of Doppler shift, to provide the radial velocity, and the imaging, to provide the transverse velocity, means that the LWA will determine the total space velocity of the CME, crucial for inferring arrival times of Earthward-bound events for geomagnetic storm predictions. A ground-based system operating with low cost HF/VHF technology, the LWA will be considerably less expensive and more reliable than planned stereoscopic space-based CME detection schemes. In addition to the practical importance to spacecraft, communication, and electrical power systems, the reliable detection and monitoring of CMEs will allow the study of the angular distribution, ranges, and line-of-sight velocities of CMEs. Additional papers at this meeting describe possibilities of the LWA for astrophysical applications (Kassim et al.) and passive solar observations (Gopalswamy et al.). Basic research in radio astronomy at the Naval Research Laboratory is supported by the Office of Naval Research.