NASA astronauts Mike Hopkins and Victor Glover have completed their second EVA (extravehicular activity, or spacewalk) outside the ISS in less than one week to continue upgrading the orbital outpost and accomplish miscellaneous tasks during US EVA-70.
The duo performed a previous spacewalk last week dedicated largely to communications upgrades for the European Space Agency’s Columbus module. Today’s spacewalk primarily focused on finishing a new battery replacement on the P4 truss that was leftover from the main effort to change out all the Station’s batteries from 2017 to 2020 as well as camera installations around the complex.
Hopkins and Glover officially took their Extravehicular Mobility Units (EMUs, or spacesuits) to battery power at 07:56 EST (12:56 UTC), officially beginning the day’s spacewalk.
The first task for the pair was to complete the final battery replacement on the P4 Truss, which brought to a close the effort, first begun in 2017 to replace all of the Station’s legacy Ni-H2 (nickel-hydrogen) batteries with modern Li-Ion (Lithium-Ion) batteries.
The batteries on the P4 Truss were replaced with new Li-Ion batteries in March 2019 via robotic operations; however, one of those batteries – on the channel 4A Integrated Electronics Assembly (IEA) – failed shortly after installation. The troublesome Li-Ion battery was subsequently removed, and an old Ni-H2 battery re-installed back in its place.
A new Li-Ion battery to replace the failed unit was flown up on SpaceX CRS-19 in December 2019 and stowed on External Stowage Platform-3 (ESP-3). Prior to EVA-70, the Special Purpose Dexterous Manipulator (SPDM), or “Dextre” robot from the Canadian Space Agency, removed the new battery from ESP-3 and installed it on the 4A Integrated Electronics Assembly.
Two old Ni-H2 batteries (one of which was removed in place of the new Li-Ion unit, and one which had been previously temporarily stowed) were transferred to ESP-3 for future disposal.
The task for the spacewalkers was to relocate an Adapter Plate from slot two to slot six on the 4A Integrated Electronics Assembly and connect the Adapter Plate to the new Li-Ion battery. The Adapter Plate is needed as one Li-Ion battery has the capacity of two old Ni-H2 batteries; however, since the Ni-H2s were installed together in pairs, the Adapter Plate is needed in order to essentially complete the circuit.
Whilst on the 4A Integrated Electronics Assembly worksite, the spacewalkers also broke torque on a bolt on a Direct Current Switching Unit (DCSU) in order to enable future robotic removal. They also removed an H-fixture – which is a small robotic interface used by Dexter – from the Beta Gimbal Assembly in preparation for the future installation of new solar arrays.
The pair then translated to Camera Port 3 (CP3) on the lower-outboard side of the S1 Truss and replaced a failed External Television Camera Group – which includes a camera, light, and pan/tilt unit. They then headed to CP13 on the Destiny laboratory and replace its camera with a new High Definition unit.
The final task of the EVA will be to replace a failed wrist camera on the Japanese Experiment Module Remote Manipulator System (JEM RMS), following which both spacewalkers will head back to the Quest airlock to conclude the spacewalk.
All told, the three camera units were installed successfully, with ground crews confirming good operations while the spacewalkers were still outside the airlock.
The duo also completed get-ahead tasks, including removal of a second H-fixture on the S4 truss.
This was the fourth spacewalk for Hopkins and the second for Glover. Hopkins was extravehicular crew member one (EV-1) using EMU 3006, which featured red stripes. Glover (EV-2) wore EMU 3009 (no stripes) during the excursion.
The EVA officially ended at 13:16 EST (18:16 UTC) after 05 hours 20 minutes.
Previous spacewalk – US EVA 69
Last week, Hopkins and Glover conducted a spacewalk on January 27 where they set up a cable and antenna for the Bartolomeo payloads platform, configuring a Ka-band communications terminal for linkage to European ground stations and removing grapple fixture brackets in preparation for future power system upgrades.
That's Victor Glover on the end of a massive Canadian Robotic Arm, a few hundred miles above the planet, traveling 17,500 mph, jettisoning an antenna cover.
Just your average Wednesday.
— Chris Bergin – NSF (@NASASpaceflight) January 27, 2021
As with US EVA-70, Hopkins was EV-1 using EMU 3006 while Glover (EV-2) wore EMU 3009 (sans stripes).
Following hatch open and egress from the Quest airlock, Hopkins began translating to the Columbus module in preparation for the start of the day’s tasks. At the same time, Glover ingressed the Space Station Remote Manipulator System – also known as Canadarm2 – and moved to the worksite.
This involved removing and reinstalling four bolts from the module’s exterior panels to allow for the placement of the terminal and then routing external wiring for power to the antenna.
This Ka-band antenna will link the module to the EDRS (European Data Relay System) network of satellites in geostationary orbit, thereby enabling faster uplink and downlink speeds between the European segment of the International Space Station and researchers on the ground.
ColKa will provide downlink speeds of up to 50 megabits per second and uplink speeds of up to 2 megabits per second. This will enable improved communications and data links in support of experiments being conducted in the orbital laboratory.
The antenna was designed and built by British, Italian, Belgian, Canadian, French, German, and Norwegian companies. Some components used for the system were qualified by the European Space Agency‘s Advanced Research in Telecommunications Systems (ARTES) program, and experience from ColKa will inform future development of the Lunar Gateway station.
European Space Agency astronaut Andreas Mogensen assisted Hopkins and Glover with the installation of the refrigerator-sized terminal by providing radio instructions from NASA’s Mission Control Center in Houston, Texas.
The next step for the crew was to release several clamps on the European Bartolomeo science payload platform holding lengths of cabling in place. Once the clamps were released, the cables were routed and installed on separate locations on the Columbus module, which will activate the Bartolomeo platform and its communications antenna.
The connectors proved to be an issue during the first part of the EVA, before good heater power was confirmed.
Bartolomeo was delivered to the Station via a SpaceX Dragon spacecraft in March 2020 and installed on the external forward side of the Columbus module the following month. Once online, Bartolomeo will house several commercial payloads externally for data collection.
Once the cable and antenna configuration was complete, Hopkins and Glover returned to the ColKa terminal and removed a cover, meant to protect the antenna inside during installation. This cover was then jettisoned overboard by Glover while on the Canadarm2, as it was no longer needed.
The two astronauts then returned to the Quest airlock to reconfigure their toolbags in preparation for the third and final task of the EVA, which involved the removal of grapple fixture brackets on the Station’s P6 (far port) truss. This will allow for the installation of future upgrades to the orbiting outpost’s solar arrays.
Following their removal, the fixture brackets were placed inside the astronauts’ toolbags and taken back inside the Station following completion of the EVA.
EVA-69 and 70 are the 233rd and 234th spacewalks in support of the International Space Station program and are scheduled to be followed by two other EVAs in the near future.
During a third spacewalk, Glover and fellow NASA astronaut Kate Rubins will work outside the ISS to prepare its power system to install six new solar arrays built by Deployable Space Systems and provided by Boeing. These panels will be transported to the station via three SpaceX Cargo Dragon vehicles and installed on later spacewalks.
Rubins and Japan Aerospace Exploration Agency (JAXA) astronaut Soichi Noguchi will continue upgrading Station components and performing maintenance for the fourth upcoming spacewalk. The dates for the third and fourth EVAs will be set at a later time.
Lead image credit: NASA