Complex sentence: In 1998, he was working as a strike-operations officer for a carrier wing in Virginia when he got the call telling him that he had been selected to join NASA's astronaut corps.
Split into simpler sentences: In 1998, he was working as a strike-operations officer for a carrier wing in Virginia. In the middle of his military career, Oefelein got the call telling him that he had been selected to join NASA's astronaut corps.