Artwork: ULA Vulcan rocket revealed

The towering structure to be used for liftoffs of NASA’s Space Launch System rolled from a construction site to launch pad 39B at the Kennedy Space Center in Florida this week, arriving at the seaside complex Friday for a week of fit checks.

United Launch Alliance said Thursday it is targeting Sept. 26 for the next attempt to send a classified U.S. government spy satellite into orbit aboard a Delta 4-Heavy rocket, following an abort Aug. 29 just three seconds before liftoff from Cape Canaveral.

Veteran astronaut John Grunsfeld, who flew five space shuttle missions before becoming the head of NASA’s science mission directorate in 2012, announced Tuesday he will leave the space agency at the end of April.