The International Space Station’s iROSA (ISS Roll-Out Solar Array) solar panel upgrade, began in 2021, has finished its initial upgrade plan with the successful installation of the last two arrays this month. The arrays for the 1A and 1B power channels were dropped at ISS aboard the CRS-28 Cargo Dragon flight after which installed in a pair of EVAs by NASA astronauts Steve Bowen and Woody Hoburg.
The iROSA project was began as a result of the continuing degradation of the Station’s existing solar panels after years in low-Earth orbit. The unique solar array complement, finished in March 2009 with the installation of the S6 truss, was able to 240 kilowatts when recent. Nevertheless, the radiation environment in orbit has degraded the arrays to the purpose where they’ll now only generate 160 kilowatts.
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A NASA diagram of iROSA solar array installation progress on the outside truss segments on the ISS. (Credit: NASA)
Installation of six recent iROSA arrays, with each able to generating 20 kilowatts, and built by Redwire, would bring back much of the Station’s lost power generating capability, with the brand new set of arrays bringing ISS back to around its initial power generation capabilities.
This upgrade will serve the Station until the top of its life, projected to be in 2030, and a brand new pair of iROSAs are targeted to fly to ISS in 2025 to further augment the ISS power supply, as announced through the EVA-88 broadcast. This is able to bring the full of iROSA arrays installed on ISS to eight.
A prototype ROSA array was flown as much as the Station aboard CRS-11 in June 2017, and successfully tested on the top of the Station’s Canadarm2 for 12 days. The iROSA upgrade project for the Station began with spacewalks in February and March 2021 to put in the iROSA mounting kits to power channels 2B and 4B. Astronauts subsequently installed the primary pair on power channels 2B and 4B during a trio of EVAs in June 2021.
This was followed by a spacewalk in September 2021 and one other one in March 2022 to put in the following pair of mounting brackets for the iROSAs to be installed on power channels 3A and 4A. A pair of EVAs followed in December 2022 to put in those panels. As well as, an EVA in November 2022 together with three EVAs in early 2023 – January, February, and April – were needed to arrange the way in which for the ultimate iROSA installations in June.
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The location of the brand new IROSAs over the present Station solar arrays. (Credit: NASA/Boeing)
ISS US EVA-87 began on Friday, June 9, at 8:24 AM CDT (13:24 UTC) with the hatch opening on the Quest airlock module. Astronaut Steve Bowen, acting as EV1 with the red stripes on the spacesuit, began his ninth spacewalk, with EV2 Woody Hoburg following him as he began his first ever EVA.
The astronauts’ primary task was to put in the iROSA array for the 1A power channel, with the installation site on the S4 truss. The 2 iROSA arrays that were brought up on CRS-28 had been faraway from the Dragon’s trunk and installed on the Mobile Transporter prior to EVA-87.
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Astronaut Woody Hoburg on the Canadarm2 during EVA-87. (Credit: NASA)
The duo’s first task, after retrieving the tools they would wish, can be to release the array meant for 1A and transport it to the 1A mod kit worksite. Woody Hoburg was the astronaut at the top of the Canadarm2 carrying the array to the worksite, while Sultan AlNeyadi operated the arm from inside the Station.
The astronauts installed the array to the mod kit and bolted it down using the Pistol Grip Tool (PGT), originally developed by NASA for servicing the Hubble Space Telescope. Bowen and Hoburg also installed cables to attach the arrays to the ISS electrical system, and this needed to be done during orbital night to forestall electric shock as a result of stray current.
Once all installation activities were finished, the iROSA array was unfurled and the deployment succeeded without issues. Hoburg finished releasing two bolts to permit the tensioners to work, to release and to tighten the panel. Meanwhile, through the process to put in the array, controllers needed to take care of longer signal dropouts than usual as a result of Typhoon Mawar’s recent hit on Guam that affected a relay station.
With the deployment complete, and with the astronauts ahead of the timeline, Bowen and Hoburg worked on some get-ahead tasks for EVA-88. Bowen rotated beams that held the highest iROSA, to permit access to the underside iROSA on EVA-88.
He and Hoburg then worked to release the iROSA for power channel 1B from one end of its temporary fitting on the Station. This took around 245 bolt turns to finish, so ending this could definitely help the astronauts through the next EVA.
Bowen and Hoburg cleaned up their safety tethers, finished their EVA activities, and entered the Quest airlock. EVA-87 ended at 2:28 PM CDT (19:28 UTC) after six hours and three minutes, with Bowen’s spacewalk experience now totaling 60 hours and 22 minutes while Hoburg finished his first EVA.
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EVA-87 by the numbers. (Credit: NASA TV)
Sultan Al Neyadi and Francisco Rubio were the intravehicular (IV) crewmembers for this spacewalk, while CSA astronaut Jenni Sidey-Gibbons was the bottom IV crewmember that talked to the astronauts. Flight controller Megan Shutilka, lead spacewalk officer Brandon Lloyd, and Flight Director Diane Dailey also were on duty for this EVA.
EVA-87 was the fifth spacewalk of Expedition 69 and the seventh conducted from ISS to this point in 2023. The 264th EVA at ISS was a whole success, however the initial ISS solar array augmentation project was not yet finished.
Steve Bowen and Woody Hoburg were tapped to conduct EVA-88 six days later, with Astronauts Rubio and AlNeyadi being the on-orbit IV crew again. Astronaut Sidey-Gibbons was the bottom IV again, while Brandon Lloyd acted as flight director. Megan Shutilka became the lead spacewalk officer.
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Mission Control in Houston during EVA-87. Flight controller Megan Shutilka is seen here with Astronaut Jenni Sidey-Gibbons to her right. Brandon Lloyd is to Megan’s left. (Credit: NASA TV)
EVA-88 began at 7:42 AM CDT (12:42 UTC) on Thursday, June 15, with Woody Hoburg taking the EV1 designation and the red stripes for his second EVA, while Steve Bowen became EV2 with the all-white spacesuit for his tenth EVA.
The duo began their spacewalk by organising safety tethers and retrieving their tools as usual, and so they finished releasing the ultimate iROSA array from its carrier. The iROSA was moved to the ability channel 1B mounting kit, situated on the S6 truss, with Steve Bowen being on the top of the Canadarm2.
NASA astronaut Woody Hoburg holds the roll-out solar array in hand after successfully releasing it from Flight Support Equipment. The duo will now move on to relocating the solar array for installation. pic.twitter.com/5mQYIj1fkM
— International Space Station (@Space_Station) June 15, 2023
After the move was finished, astronauts Hoburg and Bowen installed the iROSA on its mounting kit in a fashion just like the method they used on EVA-87. That they had to attend to hook the brand new array to the ISS electrical system, as they were ahead of schedule and needed to perform the duty during orbital night.
The astronauts used the time to start out cleanup of their worksite as a “work-ahead” task. Once the Station moved into orbital night, Hoburg and Bowen attached the iROSA’s cables to the Station’s electrical system. During this task there was an eight minute data lack of signal, in addition to an unexpected voice lack of signal. As in EVA-87, typhoon damage in Guam was forcing a station in Canberra, Australia to take up some data relay duties.
The 18.2 meter long and 6-meter wide iROSA array unfurled successfully, despite an abnormality that just isn’t expected to affect power generation capability, and Bowen finished loosening two bolts to permit the array to be tensioned. After this task was done, the 2 astronauts finished cleansing up the worksite, conducted work-ahead tasks involving a connector and a foot restraint, and headed to the Quest airlock to complete out the spacewalk.
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The iROSA for the 1B power channel being rolled out during EVA-88. (Credit: NASA TV)
EVA-88 was accomplished at 1:17 PM CDT (18:17 UTC), after five hours and 35 minutes, with Steve Bowen’s total EVA time now set at 65 hours and 57 minutes, and Woody Hoburg’s total time now at 11 hours and 38 minutes. With this EVA, Steve Bowen has passed Drew Feustel because the third most experienced spacewalker of all time, while also tying the record for many spacewalks by a US astronaut. The ISS has now seen 265 spacewalks, including eight this yr and 6 for Expedition 69, with a complete time of 70 days, 3 hours, and 27 minutes.
This yr has seen two complex and involved ISS upgrade tasks, one for the ability system, and the opposite for the Nauka module addition to the Russian segment, accomplished successfully after multiple EVAs were done up to now two years. The iROSA solar array augmentation project has taken up 15 EVAs from 2021 to 2023, while outfitting the Nauka science module took 11 EVAs plus one other one to attach the Prichal module to Nauka and ISS during that very same time span.
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Cosmonauts Dmitry Petelin (left) and Sergey Prokopyev (right) by the experiment airlock on Nauka during EVA-58. (Credit: NASA TV)
The following EVA on the Station is scheduled for one week from EVA-88. Russian EVA-59 is scheduled for Thursday, June 22, with cosmonauts Sergey Prokopyev and Dmitry Petelin will activate the experiment airlock recently installed on Nauka. EVA plans for the US side of the Station beyond this month are usually not yet set.