The Rockwell X-30 was a type of early Earth space shuttle.
An image of a Rockwell X-30 labeled as belonging to the United States of America appeared in the time stream as the timeline realigned itself. (ENT: "Storm Front, Part II")
Captain Edward Jellico kept a model of a Rockwell X-30 spacecraft in his ready room aboard the USS Enterprise-D. (TNG: "Chain Of Command, Part I")
The appearance of the craft in the time stream was mirrored.