Software patch fixes Canadarm2 anomaly, US EVA-48 postponed
NASA has postponed its planned Jan. 29, 2018, spacewalk to swap a latching end effector (LEE) on the International Space Station’s robotic Canadarm2 after robotics specialists devised a software patch to fix a communications anomaly with the recently-installed mechanism. While an exact date has not been set, the agency said it is targeting mid-February for the rescheduled outing.
Monday’s planned spacewalk was recently re-purposed to undo work performed during the Jan. 23, 2018, U.S. EVA-47, which saw the crew replace the original LEE-B “hand” at one end of the Canadian-built 57.7-foot (17.6-meter) robotic arm with a spare that was stored on the outpost in 2009. NASA said that during an initial power up of the new LEE-B, the spare effector didn’t communicate as expected on the primary string, but did so on the secondary communications string.
Because of that, on Jan. 26 the agency announced U.S. EVA-48 would be modified to re-install the original LEE-B in order to maintain system redundancy during critical operations, such as visiting vehicle berthings.
However, on Jan. 28, NASA said robotics specialists at the Canadian Space Agency developed a software patch that confirmed the communications anomaly was not hardware related and could be corrected through new software.
“A confidence test verifying the software upgrade was successfully completed Saturday night,” the U.S. space agency said in a statement.
Assuming all continues to operate nominally with the new LEE-B, the original tasks planned for U.S. EVA-48 are back on the timeline, albeit several weeks later.
When an exact date is officially set, the spacewalk will see two of the six Expedition 54 crew members—NASA’s Mark Vande Hei and the Japan Aerospace Exploration Agency’s Norishige Kanai—venture outside the outpost to move the old LEE-B from its current temporary location on External Stowage Platform 2, to the Mobile Base System (MBS) on the truss.
Additionally, the old LEE-A, which was replaced in a trio of October 2017 spacewalks, will be moved from its location on the MBS to the Quest airlock to be brought back inside the outpost. Eventually, LEE-A will be returned to Earth via a SpaceX Dragon capsule.
In the meantime, the two Expedition 54 Russian cosmonauts, Alexander Misurkin and Anton Shkaplerov, are expected to venture outside the outpost on a Russian segment-based spacewalk. The Feb. 2, 2018, excursion is planned to see the duo retrieve external science samples and install a high-gain antenna on the Zvezda service module.
Derek Richardson has a degree in mass media, with an emphasis in contemporary journalism, from Washburn University in Topeka, Kansas. While at Washburn, he was the managing editor of the student run newspaper, the Washburn Review. He also has a website about human spaceflight called Orbital Velocity. You can find him on twitter @TheSpaceWriter.