How many times did john Glen travel to outer space?

Answer 1

Twice.

On February 20, 1962, Glenn piloted the Mercury-Atlas 6 "Friendship 7" spacecraft on the first manned orbital mission of the United States. Launched from Kennedy Space Center, Florida, he completed a successful three-orbit mission around the earth, reaching a maximum altitude (apogee) of approximately 162 statute miles and an orbital velocity of approximately 17,500 miles per hour. Glenn's "Friendship 7" Mercury spacecraft landed approximately 800 miles southeast of KSC in the vicinity of Grand Turk Island. Mission duration from launch to impact was 4 hours, 55 minutes, and 23 seconds.

Glenn was invited to join STS-95 Discovery (October 29 to November 7, 1998) was a 9-day mission during which the crew supported a variety of research payloads including deployment of the Spartan solar-observing spacecraft, the Hubble Space Telescope Orbital Systems Test Platform, and investigations on space flight and the aging process. The mission was accomplished in 134 Earth orbits, traveling 3.6 million miles in 213 hours and 44 minutes. Glenn became the oldest man to go into space.

Answer 2

From what I read, twice.