The final EVA to complete an upgrade to the Space Station’s robotic arm’s end effector is taking place. EVA-48 is being conducted by Expedition 54 Flight Engineers Mark Vande Hei of NASA and Norishige Kanai of the Japan Aerospace Exploration Agency. This EVA was delayed after the previous spacewalk, EVA-47, included a software issue that was set to result in the need to reverse the work conducted on the EVA before a software patch was developed.
The main task of these spacewalks is to replace Latching End Effector-B (LEE-B) on the Space Station Remote Manipulator System (SSRMS), prior to returning one inside the Station for a return on a future SpaceX Dragon.
The LEE allows the SSRMS to grapple onto objects, and the SSRMS has one LEE on each of its ends, in order to enable the SSRMS to relocate itself around the ISS via so-called base changes.
The LEE features three snares which close around a grapple pin on target objects, in the same way that the Space Shuttle’s robotic arm used to work. This enables the LEE to grapple any object which features a Flight Releasable Grapple Fixture (FRGF) interface.
However, the LEE also has some ...