Three spacewalks, scheduled to begin in the next several weeks, are an integral element of a larger effort to replace the ISS’s antiquated electrical infrastructure.
Large solar arrays on the ISS absorb sunlight and convert it into electricity that is then used for everything from keeping the station’s inhabitants alive and comfortable to maintaining contact with Earth and propelling the station out of harm’s way.
To date, the ISS’s power needs have been met by the original ISS power system, which consisted of eight solar arrays that extended from the station’s exterior like wings. This system generated an average of 84 to 120 kilowatts of electricity. Some of the arrays, however, were over 20 years old and had been built with a 15-year lifespan in mind, so they were beginning to exhibit symptoms of wear and tear.
Although the station has experienced power outages in the past, this does not mean that the aging arrays will suddenly stop working; rather, it indicates that their efficiency is declining. In addition, the station’s power needs are growing as more and more sophisticated scientific investigations are carried out there.
In a press conference, Anthony Vareha, spacewalk flight director for the forthcoming spacewalk on November 15th, said, “Those arrays are functioning wonderful for us and providing great science, but over time with regular wear and tear they get used up a little bit.” And some of the strings that produce power on such arrays just stop functioning. That’s something that’s been part of our electricity infrastructure for years.
The ISS’s electrical system has been upgraded on a regular basis to meet its growing demands for power, and batteries have been swapped out during prior spacewalks. The next series of spacewalks will focus on installing fresh arrays.
Six new arrays will be installed as part of the power system update; these will be positioned in front of the existing arrays at an angle so that energy can be collected from both. The previous arrays measured 112 feet in length and 39 feet in width; the new arrays, known as ISS Roll-Out Solar Arrays (iROSAs), are 60 feet in length and 20 feet in width. Technology advancements in solar panels, however, imply that the modern arrays can produce nearly as much electricity as the older ones.
NASA astronauts Josh Cassada and Frank Rubio will be making their first spacewalk.
However, creating new arrays is not a straightforward task. For an iROSA array to be installed, the station’s façade will first need to be outfitted with special frames known as mod kits. Installing the scaffolding and subsequent array were two separate steps outlined by Vareha. Two of the new iROSA arrays are currently placed on the International Space Station. With the upcoming spacewalk on November 15th, scaffolding will be constructed for the final two. NASA’s Josh Cassada and Frank Rubio are going on their very first spacewalk.
With the goal of having all six arrays placed and operational by the middle of next year, two additional spacewalks are tentatively slated for November 28th and December 1st to install two more arrays to the existing scaffolding.
According to SpaceX CRS-26 resupply mission manager Chris Mundy, fresh arrays will arrive folded up on a carrier in the upcoming November 18th SpaceX flight. The arrays must then be installed, connected to the grid, and put into operation. The arrays are rolled out like a blanket during the six- to 10-minute deployment phase.
The space explorers must connect the new and existing arrays to the power grid using Y cables. At that point, “we’ll be able to route power from the legacy array and the new iROSA array into the ISS power system,” Mundy said.
According to NASA, the new arrays are being tested for potential use in future missions like the Artemis Moon program, and for enabling the space station continue operations. There is still a lot of mystery surrounding the space station’s ultimate fate. Russia, another important partner, has repeatedly threatened to withdraw its assistance, placing the ISS in a precarious situation despite powerful new enhancements, despite NASA’s announcement at the end of last year that it wants to continue operating the ISS through 2030.
Fiona Turett, flight director for an upcoming spacewalk, remarked, “Every new array adds greater power.” More science is being conducted aboard the ISS, and more systems are now operational. With this extra juice, we’ll be able to keep ISS running strong for years to come.