Photos: More Launch shots of Delta 375 rocket

NASA’s acting administrator said Tuesday he does not expect Russian cosmonauts to start launching to the International Space Station on U.S. commercial crew vehicles until next year. A proposed agreement with Russia to ensure the space station is always staffed with an international crew is awaiting U.S. government approval.

Sierra Nevada Corp. has booked at least six launches on United Launch Alliance’s new Vulcan Centaur rocket to carry Dream Chaser supply ships into orbit on cargo runs to the International Space Station beginning in 2021, becoming the first confirmed customer for ULA’s next-generation launcher.

Loaded with more than 6,000 pounds of supplies, experiments, and hardware, a SpaceX Cargo Dragon freighter docked with the International Space Station at 1:40 p.m. EST (1840 GMT) Monday, one day after taking off from NASA’s Kennedy Space Center in Florida. This was the first Dragon cargo mission to automatically dock with the space station.