NASA astronauts Sunita Williams and Barry "Butch" Wilmore are scheduled to return to Earth after an extended nine-month mission aboard the International Space Station (ISS). Their return was delayed due to propulsion issues with Boeing's Starliner spacecraft.NASA astronauts Sunita Williams and Barry "Butch" Wilmore are scheduled to return to Earth after an extended nine-month mission aboard the International Space Station (ISS). Their return was delayed due to propulsion issues with Boeing's Starliner spacecraft.