May you keep flying like superman: NASA on Stephen Hawking

In a reference to Stephen Hawking's zero-gravity experience, NASA has paid a tribute to the late theoretical physicist by tweeting, "May you keep flying like superman in microgravity". Hawking flew aboard a zero-gravity flight in 2007 and said, "It was true freedom... I was superman for those few minutes" while describing his experience to space station astronauts in 2014.