Once a rocket reaches escape velocity, it is moving at 7 miles per second. Giving away some time to accelerate, let's say 60 seconds. 73 miles divided by 7 mps, equals 10.42 seconds. Add the 60. Around 70 seconds after lift off every rocket would hit the dome going 20,000+ mph. Have you ever seen a rocket launch? If you have, your not a flat earther.