Sign up for CNN’s Wonder Theory science newsletter. Explore the universe with news on fascinating discoveries, scientific advancements and more . CNN  —  The 47-year-old Voyager 1 spacecraft is back in touch with NASA — but not out of the woods — after a technical issue caused a days-long communications blackout with the historic mission, which is billions of miles away in interstellar space. Voyager 1 is now using a radio transmitter it hasn’t relied on since 1981 to stay in contact with its