Two NASA astronauts conducted a spacewalk outside the International Space Station (ISS) on Thursday, Dec. 22, to install a fourth new iROSA (ISS Roll-Out Solar Array). The Extra-Vehicular Activity (EVA) follows a previous one on Dec. 2 that installed the third iROSA.<\/p>\n
The second EVA of the pair was scheduled for Wednesday, Dec. 21, but was postponed at the last minute when controllers determined that a piece of Russian rocket debris would pass dangerously close to the ISS, necessitating a Predetermined Debris Avoidance Maneuver (PDAM) to move the station safely out of the way and delaying the spacewalk by 24 hours. The PDAM occurred at 13:42 UTC, Dec. 21, using the Progress MS-20 spacecraft\u2019s engines.<\/p>\n<\/p>\n
Installation of the new arrays marks a continued effort to install at least six iROSAs onto the space station as part of a power augmentation program that began in 2021.<\/p>\n
The first spacewalk on Dec. 2 primarily focused on the installation of an iROSA to the 3A power channel on the starboard truss of the ISS.<\/p>\n
However, an unrelated event on Nov. 23 on the 1B electrical channel added an element to this EVA.<\/p>\n
According to NASA, on Nov. 23, \u201cSequential Shunt Unit (SSU) 1B experienced two power on resets (POR) and then tripped off. Ground teams performed a Seamless Power Channel Handover (SPCH) of the loads on Channel 1B to Channel 1A to recover power to the Channel 1B loads.\u201d<\/p>\n<\/p>\n