Mike Hicks

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This is from an infrared tracking camera on a Navy P-3. The image is taken from a pretty long-ass distance away, though I doubt the military would like to say exactly how far. A few seconds after this image was taken, the X-43A's engine ignited, probably pushing it past 5000 miles per hour. In 11 seconds while the engine was being given fuel, it traveled over 15 miles. That averages out to 4900 miles per hour—it may have gone faster at some point in the burn. NASA says that the X-43A had positive acceleration while the engine was running, which is a first for a scramjet.