The unmanned Russian Progress 48 spacecraft arrives at the International Space Station on Aug. 1, 2012. The cargo ship docked to the space station roughly six hours after it launched into orbit.
Credit: NASA TV
An unmanned Russian cargo ship arrived at the International Space Station tonight (Aug. 1), less than six hours after it launched into orbit. The successful maneuver marked the first time a same-day docking has ever been accomplished at the massive orbiting outpost.
The robotic Progress 48 cargo freighter automatically parked to the Pirs docking compartment on the Russian segment of the complex slightly ahead of schedule, at 9:19 p.m. EDT (0119 GMT Aug. 2), as both spacecraft flew over the Pacific Ocean. In addition to delivering fresh supplies to the space station, the spacecraft also tested the novel same-day rendezvous and docking procedure.
According to NASA officials, the docking test proceeded smoothly and the Progress vehicle's systems responded flawlessly throughout the shortened flight to the space station.
The Progress 48 launched into orbit atop a Soyuz rocket earlier today, at 3:35 p.m. EDT (1935 GMT), from the Baikonur Cosmodrome in central Asia. Roughly six hours later, the spacecraft arrived at the orbiting outpost.
Russia is aiming to eventually implement this same-day docking plan for future manned flights of Soyuz space capsules to the International Space Station.
"They're looking to eventually take this into the Soyuz phase," Dan Harman, NASA's space station manager of operations and integration, said in a news briefing last week. "If you can get the crew to orbit in six hours and onboard the International Space Station, that could be a tremendous benefit over the two-plus days it takes today." [Photos: Russia's 1st Same-Day Cargo Ship Flight to Space Station]
Shortening the orbital chase
Progress and Soyuz vehicles typically spend two days chasing the space station in orbit after launch. A quicker arrival to the orbiting complex could cut down the overall amount of consumables — such as food, water and fuel — needed for the onboard crew.
Docking to the station within hours of launch also minimizes the amount of time the astronauts spend inside the small Soyuz capsule, which could improve the comfort of the spaceflyers, said space station flight director Chris Edelen.
"The quicker rendezvous that you have, the less consumables you would need for the first day, and the better crew comfort in a small capsule," he said.
The idea of arriving at a destination on the same day as launch is not a new one. NASA first tested the same-day rendezvous procedures between spacecraft in the mid-1960s during the agency's Gemini program.
"This is actually old technology," Edelen explained. "Our first ground-up rendezvous on the Gemini program was a Flight Day 1 rendezvous, and the Russians have done this before, so it's sort of a back to the future."
Conducting same-day procedures, however, requires extremely precise calculations and also limits the flexibility of available launch times.
"It does impose more constraints on the geometry — the orbital mechanics — of the launch, because you have less time to catch up to the space station," Edelen said. "You've got to basically launch and be in the right spot, and the space station has to be in the right spot."
The Progress 48 spacecraft hauled 2 tons of food, clothing and supplies to the station for its Expedition 32 crew. There are currently six spaceflyers living and working aboard the orbiting outpost: Russian cosmonauts Gennady Padalka, Sergei Revin and Yuri Malenchenko, NASA astronauts Joe Acaba and Sunita Williams, and Japanese astronaut Akihiko Hoshide.
The hatch of the Progress 48 vehicle is scheduled to be opened on Thursday afternoon (Aug. 2), according to NASA officials.
The disposable Progress cargo ship is expected to remain attached to the station until December, before it is filled with trash and intentionally sent to burn up during re-entry into the Earth's atmosphere.