Maybe Aurora is back!!
" A series of unusual sonic booms were detected in Southern California, beginning in mid to late 1991. On at least five occasions, these sonic booms were recorded by at least 25 of the 220 U.S. Geological Survey sensors across Southern California used to pinpoint earthquake epicenters. The incidents were recorded in June, October and November 1990, and late January 1991.[citation needed] Seismologists[who?] estimate that the aircraft were flying at speeds between Mach 5 and 6 (3,300-4,000 mph) and at altitudes of 8-10 km (26,200-32,800 ft). The aircraft's flight path was in a north-northeast direction, consistent with flight paths to secret test ranges in Nevada. Seismologists say[who?] that the sonic booms were characteristic of a smaller vehicle than the 37-meter long shuttle orbiter. Furthermore, neither the shuttle nor NASA's single SR-71B was operating on the days the booms were registered.[9] It is not definitively known if these events can be tied to the Aurora program or to other acknowledged or secret programs.[original research?]
In the article "In Plane Sight?" which appeared in the Washington City Paper on July 3, 1992 (p.12-13), one of the seismologists, Jim Mori, noted: "We can't tell anything about the vehicle. They seem stronger than other sonic booms that we record once in a while. They've all come on Thursday mornings about the same time, between 6 and 7 in the morning."[5]
Former NASA sonic boom expert Dom Maglieri studied the 15-year old sonic boom data from the California Institute of Technology and has deemed that the data showed "something at 90,000 feet, Mach 4 to Mach 5.2. He also said the booms did not look like booms from aircraft that had traveled through the atmosphere many miles away at LAX, rather, they appeared to be booms from a high-altitude aircraft directly above the ground moving at high speeds.[citation needed] The boom signatures of the two different aircraft patterns are wildly different.[10] "
http://en.wikipedia.org/wiki/Aurora_(aircraft)
Peace
Iain