Washington, March 3-US President Barack Obama spoke on phone with NASA astronaut Scott Kelly on Wednesday, welcoming him back to Earth from his yearlong mission on the International Space Station (ISS), the White House said. Obama thanked Kelly "for his participation in important research about what it will take for us to make long journeys in space, and for inspiring a new generation of young people to pursue studies and careers in science, technology, engineering, and mathematics," Xinhua quoted the White House as saying. The US president also said Kelly's year in space would "provide critical data" to researchers trying to understand how to keep astronauts healthy during long space voyages and fulfill Obama's vision of putting American astronauts on Mars in the 2030s. "Thanks to Kelly's work, in addition to that of everyone at NASA and in the US space industry, the president believes the US will be successful in that journey to Mars," the statement added. Kelly landed in Kazakhstan on Tuesday with his Russian counterparts Mikhail Kornienko and Sergey Volkov after a 340-day mission aboard the International Space Station. It is the longest continuous stay in space for an American astronaut.