A prototype of a passenger jet designed to succeed the supersonic Concorde broke the sound barrier for the first time on Tuesday above the Mojave Desert in California. Why it matters: Exceeding Mach 1 speed — 770 miles per hour — is an important milestone in the quest by Boom Supersonic,

On its 12th test flight, the Boom XB-1 prototype broke the sound barrier three times and achieved a top speed of Mach 1.1.

Boom’s XB-1 jet breaks sound barrier on first supersonic flight - Boom’s inaugural XB-1 supersonic test flight reached speeds of more than 850 miles per hour