Tomorrow on “Two Way Street,” we’re talking to astronaut Scott Kelly , who holds the American record for most consecutive days in space. His 340 days aboard the International Space Station (ISS) is the subject of his new memoir, “ Endurance: A Year in Space, A Lifetime of Discovery .” Kelly talks about the challenges of long-term spaceflight, including being unavailable to his loved ones. “If something happens to them,” Kelly says about family, “you’re not coming home.” That was the case when