Expedition 61 Flight Engineers Christina Koch and Andrew Morgan on Sunday. (Twitter)

Two NASA astronauts have successfully wrapped up a seven-hour and one minute spacewalk, marking the completion of the first of the five spacewalks to upgrade the station's power systems this month.

Beginning the replacement of nickel-hydrogen batteries with newer, more powerful lithium-ion batteries on the far end of the station's port truss, Expedition 61 Flight Engineers Christina Koch and Andrew Morgan of NASA concluded their spacewalk at 2.40 pm EDT on Sunday, the US space agency said.

The astronauts were also able to accomplish get-ahead tasks, including the removal of an additional nickel-hydrogen battery, originally scheduled for the second spacewalk.

These new batteries provide an improved power capacity for operations with a lighter mass and a smaller volume than the nickel-hydrogen batteries.

On October 11, Mr Morgan and Ms Koch are scheduled to venture outside again for another spacewalk to continue the battery replacements on the first of the two power channels for the station's far port truss, NASA said.

The next spacewalks dedicated to the battery upgrades are scheduled on October 16, 21 and 25.

After completion of the battery spacewalks, the second half of this sequence of spacewalks will focus on repairs to the space station's Alpha Magnetic Spectrometer.

Dates for those spacewalks are still being discussed, but they are expected to begin in November.

Space station crew members have conducted 219 spacewalks in support of assembly and maintenance of the orbiting laboratory.

Spacewalkers have now spent a total of 57 days 6 hours and 27 minutes working outside the station.