Nasa Reveals What Happens to Human Waste Produced by ISS Astronauts

During his 342-day-long stay on the orbiting laboratory, Kelly will produce nearly 180 pounds (82 kg) of faeces.

"The waste will be discharged at intervals from the space station and will burn up in the Earth's atmosphere and look like shooting stars," Nasa said in an infographic release on Monday.

The mission, which also includes Russian cosmonaut Mikhail Kornienko, aims to better understand effects of long-term living in space on humans.

Kelly will also drink 730 litres of recycled urine and sweat during his term aboard the ISS.

"Astronaut Scott Kelly will see 10,944 sunrises and sunsets during the 'Year in Space' mission. You will see 684," the US space agency said.

Kelly will exercise more than 700 hours during his year-long mission to keep his bones, muscles and heart strong.

He will also run about 648 miles on a specialised treadmill during the "Year in Space" mission.

"At that rate, it would take him more than 216,000 years to run to Mars, which is 140-million miles from Earth," the infographic read.

About 383 experiments will be conducted during Kelly's stay.

To get the same radiation exposure that astronaut Kelly will experience during the "Year in Space" mission, you have to fly from Los Angeles to New York 5,250 times, the infographic read.