NASA astronauts reveal the fourth gradient solar array during a spacewalk outside the space station
The International Space Station (ISS) has a new fourth solar array thanks to the work of two NASA astronauts on a seven-hour spaceflight.
Frank Rubio and Josh Casada, both flight engineers on the space station’s Expedition 68 crew, ventured back outside the orbital complex on Thursday (December 22) to install the ISS Roll-Out Solar Array (iROSA) system to augment the station’s power supply. . The spacewalk was almost a repeat of the extravehicular activity (EVA) that Rubio and Casada did nearly three weeks ago, but this time it focused only on an energy conduit located on the port side gear.
The two astronauts also reversed roles, with Rubio serving as cosmonaut (EV-1) for Thursday’s picnic. Rubio and Casada began the spacewalk at 8:19 a.m. EDT (1319 GMT), exiting the US Quest airlock and quickly getting to work on their assigned tasks. When Cassada installed a foot restraint at the end of the station’s Canadarm2 robotic arm, Rubio configured cables that would later be attached to connect the new array to the station’s 4A power conduit.
Related: NASA astronauts deploy a collapsible solar array during a spacewalk outside the space station
The two astronauts then worked together to free the iROSA from the pad it was launched on and temporarily stow it on the station. Like the array installed Dec. 3, the 4A iROSA was delivered to orbit by the SpaceX CRS-26 Dragon cargo spacecraft, which arrived at the International Space Station on Nov. 27.
After Rubio released the final bolt holding the array in place, Cassada, now at the end of the robotic arm, grabbed the assembly to move it to its installation site. NASA astronaut Nicole Mann was at the controls of Canadarm2, with Koichi Wakata of the Japan Aerospace Exploration Agency (JAXA) coordinating her work with Cassada overseas.
“Just head up, Koichi,” he said over the radio while taking a break between moves, “That last one pauses a bit quickly. If you see him ramping up the next one, can you give me a heads up? Cool.” Despite being weightless in the microgravity environment of space, the 750 lb (340 kg) mass still has significant lethargy when moved.
Rubio moved along the truss to meet the location of Cassada the P4. The two spacemen then unfolded the iROSA from its launch configuration and then secured the array over a mounting bracket mounted on an earlier EVA. Using a power tool specifically designed for astronauts to use on spacewalks, Rubio tightened the four screws on the right and left sides of the iROSA to hold the assembly open.
After waiting for the space station to be in a state of “eclipse,” or when it was in Earth’s shadow, so that the existing solar array wings would not produce electricity, Rubio and Casada then integrated iROSA into power channel 4A by connecting the cables connecting the new array to the station.
At that point, all that was left to do was let iROSA open up. With two bolts fired, the potential energy stored by the carbon composite booms caused the array to slide on its own to its full length of 63 feet (19 m) without the need for a motor.
“We can finally run this microwave we wanted to run,” Casada joked about the extra power from the new array.
The whole process took about 10 minutes. Casada tightened two of the screws to strengthen the array and the installation was complete.
ISS Roll-Out Solar Arrays are installed in front of, and partly overlaying, existing partially recessed solar panel wings. When used in conjunction and once all six iROSA systems are in place, the upgraded power system will increase the space station’s electricity supply by 20 to 30 percent.
Casada and Rubio completed the spacewalk by cleaning and inventorying their instruments before entering the airlock at 3:27 p.m. EDT (2027 GMT), seven hours and eight minutes after they began EVA.
Thursday’s flight was scheduled for Wednesday, but was delayed by a day because the space station needed to maneuver out of an approaching piece of Russian rocket debris. This was the third spacewalk for both Rubio and Casada. They have now logged 21 hours and 24 minutes in the vacuum of space.
The EVA was the twelfth of the year, the fourth for Expedition 68 and the 257th since 1998 to support the assembly and maintenance of the International Space Station.
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