Watch live: Koch, Meir begin spacewalk to continue space station battery replacements

STORY WRITTEN FOR CBS NEWS & USED WITH PERMISSION


After an exceptionally busy few months, astronauts Christina Koch and Jessica Meir, making history’s second all-female spacewalk, floated back outside the International Space Station Wednesday to replace a set of aging solar array batteries.

After an exceptionally busy few months, astronauts Christina Koch and Jessica Meir, making history’s second all-female spacewalk, floated back outside the International Space Station Wednesday to replace a set of aging solar array batteries.

Floating in the station’s Quest airlock, the astronauts switched their spacesuits to battery power a 6:35 a.m. EST, officially kicking off the 225th excursion devoted to station assembly and maintenance. It is Meir’s second spacewalk and the fifth for Koch, who is wrapping up a record 328-day stay in space.

For identification, Meir, call sign EV-1, was assigned a suit with red stripes around the legs and helmet camera No. 11. Koch, EV-2, was assigned an unmarked suit and is using helmet camera No. 18.

NASA is in the process of replacing all 48 of the space station’s older-generation nickel-hydrogen batteries with 24 more powerful lithium-ion units, along with circuit-completing “adapter plates” to fill in for batteries that were removed but not replaced.

The new batteries are arranged in sets of six in integrated electronics assemblies, or IEAs, at the bases of the station’s four main solar array wings. Each wing is made up of two extendable blankets of solar cells and the electricity they generate is delivered throughout the station using eight electrical buses, or channels, two per IEA.

NASA astronaut Christina Koch works with a spacesuit on the International Space Station. Credit: NASA

In 2017, spacewalkers replaced the 12 right-side inboard solar array batteries with six lithium-ion units. In March 2018, the 12 left-side inboard batteries were replaced by another six LiOH batteries. NASA currently is working to replace the 12 left-side outboard batteries. The final set of lithium-ion batteries will be installed in the right-side outboard IEA later this year.

Koch and astronaut Drew Morgan installed three of the left outboard array’s six lithium-ion batteries and adapter plates last Oct. 6 and 11. But shortly thereafter, engineers discovered one of the three battery charge-discharge units in that circuit had failed after 19 years of service, sidelining one of the new batteries.

Koch and Meir staged the first all-female spacewalk last Oct. 18, removing the failed BCDU and installing a replacement. The faulty unit was returned to Earth earlier this month aboard a SpaceX Cygnus cargo capsule. The device will be refurbished and re-launched on a future resupply mission.

In the meantime, with the BCDU swap-out complete, NASA managers opted to press ahead with three higher-priority spacewalks by Morgan and Luca Parmitano in November and December to repair the cooling system in a $2 billion cosmic ray detector mounted on the solar power truss. A fourth spacewalk is planned later this month to verify the repairs and to re-install insulation.

Koch and Meir were assigned to complete the left-side outboard battery replacements during another two spacewalks, the first Wednesday and the second next Monday. During Wednesday’s excursion the astronauts plan to remove three nickel-hydrogen batteries, install two new lithium-ion units and one adapter plate.

If all goes well, Koch and Meir will finish the job Monday, removing three more old batteries and installing the final lithium-ion power pack.

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