Video: Soyuz launcher ready for rollout

Soyuz TMA-15M commander Anton Shkaplerov, flanked on the left by flight engineer Samantha Cristoforetti and on the right by NASA astronaut Terry Virts, are scheduled for liftoff from complex 31 at the Baikonur Cosmodrome in Kazakhstan on Sunday.

The Dragon spaceship poised for launch Tuesday will carry more than 2.5 tons of equipment for the International Space Station’s six-person crew, making the first U.S. supply delivery to the orbiting research complex since the crash of an Antares cargo rocket in October.

Two NASA astronauts and an Italian flight engineer are sheltering in the space station’s Russian segment as mission control analyzes a possible leak of toxic ammonia coolant aboard the complex.