The first plane ever to fly faster than the speed of sound was the X-1 in nineteen forty-seven.

VOA: special.2010.07.07

One of them,the Apollo-11, traveled to the moon just seven months after the last X-15 flight.

VOA: special.2010.07.07

The only tragedy connected with the X-15 program happened in nineteen sixty-seven.

VOA: special.2010.07.07

He later flew the North American X-15 seven times, ultimately reaching an altitude of 207, 500 feet.

FORBES: Neil Armstrong's Immortal Footprint

In research presented Thursday at a Heart Rhythm Society meeting in Boston, 110 patients at seven hospitals who were checked with X-rays showed a 25% rate of externalized leads.

WSJ: Agonizing Choices for Heart Patients