Complex sentence: SpaceShipOne's first official spaceflight, known as flight 15P, was piloted by Mike Melvill and, a few hours after that flight, he became the first licensed commercial astronaut.
Split into simpler sentences: SpaceShipOne's first official spaceflight, known as flight 15P, was piloted by Mike Melvill. Likewise, a few hours after that flight, Melvill became the first licensed commercial astronaut.