5 miles per second

Mach 25 is 5 miles per second.

Thats DC to Bethesda in one second.

Lockheed Martin and the Defense Advanced Research Projects Agency are investigating why contact with the first HTV-2 test vehicle was lost soon after launch on a mission to demonstrate technology for high-performance, long-endurance hypersonic flight.

The third stage of the Orbital Sciences Minotaur IV Lite booster successfully completed energy-management maneuvers, released its clamshell payload fairing and deployed the HTV-2 at the edge of the atmosphere, but telemetry signals from the hypersonic glider were lost about 9 minutes into the mission, DARPA says.

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