Part one of battery-upgrading spacewalk, a success!

Two NASA astronauts had successfully finished the first wave of the series of extravehicular activity (EVA) intended for upgrading the laboratory's power system.

Changing the batteries is not an easy feat. Expedition 61 flight engineers Christina Koch and Andrew Morgan had to work in the space vacuum for more than seven hours—from 7:39 a.m. EDT (1139 GMT) to 2:40 p.m. EDT (1840 GMT). But Morgan still called the experience as "pretty awesome" after seeing the Earth below.

There are a total of eight solar array wings, with four on each side of the space station. Depending on the location of the station, it could either feed electricity to the system or charge the four large batteries mounted at the base.

Upgrading the power system is divided into five parts, with Koch and Margon's spacewalk as the first. The duo worked on the two older power storage units located at the left port.

The set of batteries they installed are lithium-ion batteries, which can hold twice as much as the previously used nickel-hydrogen batteries. With the size of 40 inches long by 37 inches wide by 19 inches height, it is about half the size of a refrigerator. It has arrived at the station on Sept. 28 through Japan's H-II Transfer Vehicle-8 (HTV-8).

The operation would not be a success without the assistance of NASA astronaut Jessica Meir, who was working inside the station. By using the Canadarm 2 robotic arm, she repositioned the pallet so that the duo can easily reach the replacement batteries.

The first battery was installed about 50 minutes after the old one was removed.

After getting a "go signal," the duo worked again to remove the second battery. And once done, they secured the nickel-hydrogen batteries before going back inside the space station's airlock.

"It has been a wonderful day," said Koch, who served as the EV1 (or the lead spacewalker) and has worn the Extravehicular Mobility Unit (EMU) spacesuit with red stripes. Her partner was identified as EV2 and has worn a suit without identifiers.

This EVA was both Koch's and Morgan's second spacewalks. 

Future plan

Four more batteries are planned to install. Koch, Morgan, and Meir will be taking turns on the first three—dated on October 11, 16, and 21. It is noted that the EVA on the 21st will be the first-ever all-female spacewalk, as Meir and Koch will be doing it. The last wave will take place on Oct. 25, with Meir and the Expedition 61 commander Luca Paramitano of Europe Space Agency (ESA).

After upgrading the power system, another EVA is scheduled on Oct. 31, led by Russian cosmonaut Aleksandr Skvortsov and Oleg Skripochka. Then in November, Morgan and Parmitano will pair up to repair the Alpha Magnetic Spectrometer (AMS) cosmic-ray detector.The space station began its operation in 1998, and space researchers have spent a total of 57.3 days working inside it. About 219 spacewalks—including the October 16th EVA—have been conducted since then.