NASA Spacewalkers Resume ISS Battery Upgrade
HOUSTON—Spacewalking NASA astronauts Jessica Meir and Christina Koch resumed efforts Jan. 15 to complete the replacement of aging batteries on the International Space Station’s solar panel truss—an activity that was interrupted three months ago by the failure of a battery charge/discharge unit (BC/DU).
Meir and Koch are to complete the overall task that was begun in October of replacing 12 of the 19-year-old nickel-hydrogen (NH) batteries with six more-efficient lithium-ion (Li) batteries during a Jan. 20 spacewalk.
The exchange was interrupted after six of the bulky NH batteries had been replaced during excursions on Oct. 6 and 11, when a power decline was detected in the 2B power channel. The drop was blamed on an aging BC/DU, which was replaced by Meir and Koch during an Oct. 18 spacewalk, the first ever by two women astronauts.
The failed BC/DU was returned to Earth aboard a NASA-contracted SpaceX Dragon resupply mission Jan. 7 to undergo analysis. After evaluating another ground-based BC/DU, ISS managers decided to proceed with the upgrade by thermally conditioning the BC/DU involved in remaining exchange activities to a warmer setting.
During the latest, 7 1/2 hour spacewalk, Meir and Koch removed four NH batteries and replaced them with two Li batteries and adapter plates on the 4B power channel. Three of the NH batteries were prepared for eventual disposal and one was reserved if needed as a power source in a contingency.
During the October spacewalks, Koch and NASA astronaut Drew Morgan removed six NH units and replaced them with three of the Li batteries along with adapter plates on the 2B power channel.
During the Jan. 20 spacewalk, Meir and Koch are to remove the last two NH batteries at the worksite on the most distant reach of the station’s port side solar power truss, known as P-6, and install a final Li. unit.
Similar ISS life extension battery upgrade campaigns were carried out with NASA spacewalks in March 2019 and January 2017. A final series of battery exchanges, planned for later this year, will complete the upgrade of eight solar power channels distributed along the orbiting science laboratory’s nearly 360-ft.-long solar power truss to ensure the flow of electricity to life support systems and research activities while the ISS is in darkness, which is about half of every 90-min. orbit of the Earth.
Meir and Koch completed their Jan. 15 spacewalk, the second ever conducted by two women, at 2:04 p.m. EST.
“Awesome job,” NASA’s Mission Control said.
After departing the station’s U.S. segment airlock, the spacewalkers made their way to P-6. While moving hand over hand, Koch’s spacesuit helmet light and camera assembly dislodged. After an unsuccessful attempt to re-attach the devices—which help illuminate worksites in darkness and provide flight controllers on Earth with imagery—resulted in a 30-min. delay, the spacewalkers were instructed by Mission Control to resume their activities but stay close to one another so Meir’s helmet light and camera could illuminate and monitor both astronauts.
If the Jan. 20 spacewalk goes as planned, European Space Agency astronaut Luca Parmitano and Morgan are to join for a spacewalk on Jan. 25 to complete an upgrade of the thermal control system for the $2 billion Alpha Magnetic Spectrometer, the large, nearly nine-year-old cosmic ray observatory attached to the station’s exterior to study dark matter and antimatter.
Work to equip the AMS with a new Upgraded Tracker Thermal Pump System (UTTPS) was also interrupted by the BC/DU issue after successful spacewalks by Parmitano and Morgan to complete most of the complex upgrade on Nov. 15, Nov. 22 and Dec. 2.
The final AMS excursion is to be focused on leak checks of the new UTTPS coolant pumps and eight carefully spliced liquid carbon dioxide coolant tubes, as well as the reinstallation of thermal protection blankets.
The AMS was developed by NASA and the U.S. Department of Energy with scientists from 56 partner institutions in 16 countries. The 15,250-lb. observatory was installed on the ISS starboard solar power truss by a space shuttle crew. It was initially expected to function for three years and not developed to be maintained with spacewalks.