英语文摘:SpaceX Dragon spacecraft arrives at Int'l Space Station

WASHINGTON, July 20 (Xinhua) -- SpaceX's uncrewed Dragon cargo ship arrived at the International Space Station on Wednesday, carrying a crucial docking port for future American commercial spacecraft and a DNA sequencing device.

NASA astronauts Jeff Williams and Kate Rubins reached out with the station's robotic arm and grappled the spacecraft at 6:56 a.m. EDT (1056 GMT), as the orbital laboratory flew 252 miles (about 406 kilometers) over the Great Lakes, U.S. space agency NASA said.

Dragon carried almost 5,000 pounds (2,268 kilograms) of cargo for its ninth commercial resupply mission for NASA, including the first of two international docking adapters, which NASA said will set up the station for "a new era of human spaceflight."

The hardware is a ring weighing more than 1,000 pounds (454 kilograms) that will provide a standardized connection point for future crewed spacecraft to automatically dock with the station.

Its first users are expected to be the Boeing Starliner and SpaceX Crew Dragon, both now in development in partnership with NASA's Commercial Crew Program.

The station's robotic arm will retrieve the docking port from Dragon's uNPRessurized trunk and spacewalkers will complete the installation in August, said NASA.

The rest of the cargo included a miniaturized device that will allow DNA sequencing in space for the first time. The samples in this first test will be a mix of a common virus, a bacteria and mouse cells, in a bid to see how well the machine operates in microgravity.

Another interesting science experiment aboard this flight is an investigation that will study how microgravity changes the human heart, and how those changes vary from one individual to another.

Dragon was launched aboard a Falcon 9 rocket early Monday and will remain docked with the station until Aug. 29.