Editor's Note: Updated at 18:00. EDT (2200 GMT) after the NASA Media Conference.
HISTORY FOR CBS NEWS AND USED WITH AUTHORIZATION
Two NASA astronauts will be taking part in the first women's space walk this week, a critical outing to help restore power failure after a device failure that occurred after replacing new batteries in the station's solar station during two previous spacewalks ,
Astronaut Christina Koch, making her fourth spacewalk (EVA), and Jessica Meir making her first spacewalk, will be floating outside the station Thursday or Friday to fix a faulty 19-year battery charge. Discharge unit (BCDU) at the left end of the station's current transformer and install a replacement for 233 kg.
Problems with the old unit controlling the charging and discharging of a newly installed solar array battery in the space station forced NASA to postpone three upcoming spacewalks for battery insertion, including a scheduled outing on Wednesday from Meir and the Astronaut Drew Morgan, until the engineers found out what had gone wrong.
Troubleshooting failed another BCDU earlier this year after an identical lithium-ion battery was installed in a different circuit. The station's power system includes 24 charge controllers, and there are only three spare parts available in orbit. Engineers want to make sure that there is no generic problem before proceeding with additional battery installations.
"There will be a lot of emphasis in the near future on understanding how we could operationally address any concerns. Install these new batteries and integrate them into these BCDUs in the future," said Kenny Todd, manager for Operation and integration of space stations.
"It is absolutely alarming at this point if you do not know what's going on," he said. "We're still scratching our heads and looking at the data, hopefully we can sort this out in a relatively short time."
Koch and Meir have already been assigned to one of the three remaining battery-change spacewalks, and both are generic It will be the first EVA of two women in the 54 years since the first spacewalk of the late Soviet cosmonaut Alexey Leonov in 1965. The cosmonaut Svetlana Savitskaya was the first woman In 1984, astronaut Kathryn Sullivan followed NASA astronaut David Leestma on a shuttle space walk and Meir will be the 15th, with the exception of Savitskaya, all are current or retired NASA astronauts.  Megan McArthur, an experienced spacewalker and deputy head of the Astronaut Office at the Johnson Space Center, told reporters that it would be useful to bring Koch and Meir together for the BCDU spacewalk.
"In any case, it will be an exciting event that we will certainly think about later," she said. "But in truth, in view of the upcoming workload, this was the right crew to accomplish these tasks." All our crew members are fully qualified for this, and the fact that there will only be two women reflects the fact that we have so many capable, qualified women in the office. … That's a big advantage for us all. "
Along with her experience on the spacewalk, Koch is in the process of recording the longest single space flight of a woman of any nationality. When she returns to Earth next February, she will have spent 328 days in space, just 12 days behind the US record of astronaut Scott Kelly.
NASA originally planned that chef and astronaut Anne McClain's first female spacewalk last March to install a different set of solar array batteries. However, the size of the available space suits of the station became a problem.
Only one of the four suits aboard the station was configured with a mid-sized torso section at this time. Suits can be resized in orbit. To change the fit of an upper body, the coolant lines and other components must be repositioned and the systems re-tested. This process takes about 12 hours.
McClain wore the mid-size suit during a first spacewalk with astronaut Nick Hague and initially planned to wear a larger suit for Koch's second spacewalk. But McClain decided after the first outing that she preferred the medium. Given the time required to change another suit in size, she decided to postpone her second outing until the mid suit was available again. As a result, Hague took her place in the all-female EVA.
Assignments for the current battery change EVAs were announced earlier this month, with Koch and Meir completing the fourth of five planned outings. Both women were expected to attend three EVAs each. It is not yet known when the remaining three battery-mounting space walks will be made.
Work on replacing the space station's solar batteries began with a first series of spacewalks in 2017.
The station is equipped with eight giant solar panels arrayed in pairs, four at each end of the truss. Each wing pair is equipped with an integrated electronics unit (IEA) that was originally equipped with 12 nickel-hydrogen batteries each to deliver power as the laboratory complex flies through the Earth's shadow.
For the station to operate at peak efficiency In the 2020s, NASA is currently replacing all 48 original batteries with 24 of the more powerful lithium-ion models, along with completed "adapter plates" replacing batteries that are removed. but were not replaced.  Each solar wing and each IEA feeds two of the station's eight electrical channels, and each channel has three components called battery charge-discharge units (BCDUs) that control the recharge in sunlight.
Located in the adjacent IEA For the batteries they control, the BCDUs also supply stored power when the lab is in the shadow of the earth, discharging the batteries. Each BCDU controls the charging / discharging of two nickel-hydrogen batteries or a lithium-ion battery / adapter plate.
A set of six lithium-ion batteries and adapter plates was installed in 2017, a second set was carefully installed in March of last year, the right and left inboard arrays of the space station. The third set of six will be installed on the left side of the truss, a segment called Port 6 or P6 for short. A last sentence will be installed for the rightmost arrays – S6 – next year.
"This is an on-going maintenance operation that we introduced a few years ago with the purchase of lithium-ion batteries and is now using the technology even more intensively," Todd said before the previous spacewalks.
"Just like your home rechargeable batteries, they will not charge so well over time, they will not hold so much charge. Throughout the life of the station, we knew this would happen and that the batteries would have to be replaced. "
During space walks October 6-11, Koch and Morgan removed six nickel-hydrogen batteries from the Channel 2B into the P6-integrated electronics assembly and replaced them with three lithium-ion batteries and three adapter plates. On three more space walks on October 16, 21 and 25, batteries and adapters for the 4B power channel should be installed.
However, after the second battery-change spacewalk last Friday, air traffic controllers noticed one of the three BCDUs in the electronics of the power channel 2B device malfunctioned. There was no immediate impact and no equipment needed to be shut down. However, the channel will produce 4 to 5 kilowatts less power than expected from a set of new batteries, and a subsequent failure could trigger at least some equipment shutdowns.
A similar error occurred in March last year after new batteries were installed in the inboard 4 IEA. In this case, the robotic arm of the station was used to install a replacement. The failure was considered a random incident at this time. However, since a second BCDU failed in a similar fashion, NASA managers want to make sure that they fully understand the problem before proceeding to install the battery.