The Enterprise's sensors registered the cube as being entirely solid, massing around 11,000 metric tons, and each edge measuring 107 meters. The device remained at a short distance from the Enterprise but would alter it's course to block the Enterprise when she altered her course. It was later revealed that the cube was sent out by the alien, Balok, who wished to test how the Enterprise would respond to the threat it posed. (TOS episode: "The Corbomite Maneuver")