Washington, Feb 3 (IANS): After 13 different astronauts conducted 14 spacewalks over several years, the primary power system of the International Space Station (ISS) has now been fully upgraded to lithium-ion technology, NASA has said.

The space station's primary power system originally used nickel-hydrogen batteries for storage, the US space agency said on Tuesday.

In 2009, the International Space Station Programme conducted a preliminary risk and feasibility study to evaluate the use of lithium-ion batteries to replace the power storage system.

In early 2011, the programme approved development of the new battery.

Production started in late 2014, and in December 2016, NASA began the process of replacing the aging batteries with new lithium-ion batteries.

Upgrades to the space station are designed to maximise the capability of the orbiting laboratory to support scientific research and technology development.

The station is also open for business, and serves as a base to continue the development of a robust commercial economy in low-Earth orbit.

In addition, the work being done to maintain the station and conduct research are helping prepare NASA for future long-duration missions to the Moon with Artemis, and eventually, to Mars.

The new batteries were provided by Boeing, who also worked with Aerojet Rocketdyne and others for certain components.

The space-grade lithium-ion cells were provided by GS Yuasa Lithium Power, NASA said, adding that one lithium-ion battery and corresponding adapter plate replaces two nickel-hydrogen batteries.