Washington, 22 Jumada I,1437 AH, 02 March,2016 , SPA -- US astronaut Scott Kelly returned to Earth on Wednesday after setting a US record by spending nearly a year in space aboard the International Space Station (ISS), dpa reported. Kelly returned at 10:26 am Wednesday (0426 GMT) along with two Russian cosmonauts, Mikhail Kornienko and Sergey Volkov of the Russian space agency. Kelly and Konienko spent 340 days aboard the ISS participating in experiments, doing repairs and going on space walks. The nearly year-long mission was part of a NASA study to learn about the impact of long duration space flights on the human body. Kelly presented a special opportunity for study because he is a twin. NASA scientists compared his health data with that of his twin brother, Mark Kelly, a former astronaut, to analyze the changes that occur in space flight on the human body. According to NASA, it is the first experiment conducted on two people with the same genetics in different space environments. -- SPA 11:36 LOCAL TIME 08:36 GMT www.spa.gov.sa/w