Cut-back crew for ISS launch
20 April 2017 Last updated at 15:30 BST
There was an empty third seat on the Soyuz capsule which blasted off from the Baikonur Cosmodrome in Kazakhstan on Thursday.
Nasa astronaut Jack Fischer, 43, and Russian cosmonaut Fyodor Yurchikhin, 58, lifted off at 1:13pm local time (0713 GMT).
But Russia is scaling back its staff on the ISS until a long-delayed space laboratory is sent to the outpost in 2018.