Astronaut Scott Kelly plays ping-pong with water ball to mark 300 days in space

If astronaut Scott Kelly has endeared himself to space watchers for one thing, it is his real time photos and videos of the outer world. The world definitely has a clearer picture of what goes on inside the International Space Station (ISS) now.

During his days aboard the ISS, Kelly introduced us to the first orange zinnia flower that blossomed in space, eaten the first lettuce crop grown in Nasa's plant production unit Veggie, and sent several phenomenal photos of the Earth, moon and sun.

The most recent adventure of Kelly, 51, in zero gravity shows the amazing sight of him playing ping-pong with a water bubble, or what he describes as a water ball. "Try this, Mary Poppins! Super-hydrophobic polycarbonate ping pong paddles and a water ball in space!" he wrote on Twitter as he posted a video of him playing the game.

"Neat stuff," he says while bouncing the bubble between two hydrophobic paddles. Kelly posted the video to mark 300 days of living in space.

Scott Kelly, commander of Nasa's current Expedition 45, is on a year-long US-Russian mission along with cosmonaut Mikhail Kornienko to understand the effects of long-duration spaceflights on the human body. The two of them are participating in studies on how the human body adjusts to weightlessness, isolation, radiation and stress of long-duration spaceflights, which is critical to advancing the journey to Mars.

"The investigations in progress on the space station will help scientists better understand how to protect astronauts as they travel into deep space and eventually on missions to the Red Planet," the space agency said.

Scott Kelly has surpassed all previous records to become the first astronaut to spend the most time in space. Upon his return to Earth, which is scheduled for 3 March at the end of the current mission, Kelly will have compiled 522 total days living in space during four missions.