Robotic Russian Supply Ship Arrives at Space Station

An unmanned Russian cargo ship arrived at the International Space Station late Monday (July 18), delivering tons of supplies even as yet another cargo ship launched toward the orbiting lab.

The Progress 64 cargo ship – operated by Roscosmos, the Russian space agency – docked automatically with the Pirs docking compartment of the space station at 8:20 p.m. EDT (0020 July 19 GMT) carrying a haul of food, supplies and fuel for the six astronauts on board.

The spacecraft launched into orbit on Saturday (July 18) from the Baikonur Cosmodrome in Kazakhstan. It traveled two days in orbit before reaching the space station as both craft were flying 250 miles (402 kilometers) over Santiago, Chile.

Meanwhile, another cargo ship is on its way to the space station. SpaceX successfully launched its Dragon spacecraft earlier Monday at 12:45 a.m. EDT (0445 GMT). It's carrying nearly 5,000 lbs. of cargo (2,267 kilograms), including a new docking adapter for the station to accommodate commercial space taxis for astronauts. The spacecraft will arrive at the station on Wednesday (July 20).

While Dragon can carry refrigerated supplies to space, the Progress spacecraft is used for carrying supplies, replacements for broken or used-up items on station, dried food and a small batch of fresh fruit.

Now that Progress 64 has docked at the station, the Expedition 48 crew can begin unloading the spaceship's 3 tons (2.7 metric tons) of supplies. Over the next six months, the spacecraft will remain docked to the station and serve as a trash can for any unneeded items. It will then undock in January and burn up in the Earth's atmosphere.

Besides Russia's Progress spacecraft and SpaceX, the other main suppliers for space station cargo is Orbital Sciences Corp., which operates the Cygnus spacecraft, and the H-2 Transfer Vehicles launched by Japan.

Follow Elizabeth Howell @howellspace, or Space.com @Spacedotcom. We're also on Facebook and Google+. Original article on Space.com.