NASA astronaut Anil Menon and European Space Agency astronaut Sophie Adenot are preparing to return outside the International Space Station on Tuesday, Aug. 25, to complete the replacement of a space-to-ground communications antenna. The work continues an antenna replacement effort that the pair began during their Aug. 18 spacewalk.
Finishing the ISS Antenna Replacement
The main objective of the Aug. 25 spacewalk is to install a spare space-to-ground antenna on the station’s Z1 truss segment, located above the Unity module. The antenna supports high-speed communications between the International Space Station and mission controllers on Earth.
During the operation, Menon will ride on the station’s Canadarm2 robotic arm to retrieve the replacement antenna. Adenot will release the spare unit from an external storage platform before the astronauts work together to position it on the Z1 truss.
Once the antenna is mechanically installed, Menon and Adenot will make the electrical and data connections required to activate the system. These connections are a critical part of restoring the replacement antenna for high-speed data transmissions with mission control.
Work Continues From the Aug. 18 Spacewalk
The upcoming excursion follows a spacewalk on Aug. 18 during which Menon and Adenot began the antenna replacement work. The astronauts completed part of the planned maintenance but did not finish installing the spare antenna, requiring another excursion to complete the job.
The Aug. 25 activity is expected to begin at about 8:35 a.m. EDT and last approximately six and a half hours. NASA plans to begin live coverage at 7 a.m. EDT.
Menon will serve as spacewalk crew member 1 and will be identifiable by red stripes on his spacesuit. Adenot will serve as crew member 2 and will wear an unmarked suit.
Additional Navigation Hardware Could Be Replaced
If the astronauts complete the antenna work with sufficient time remaining, NASA plans a secondary “get-ahead” task involving replacement of a retroreflector on the forward port of the station’s Harmony module.
A retroreflector is designed to return incoming light toward its source and forms part of the navigation infrastructure used by spacecraft approaching the station. Replacing the device is intended to improve navigation data available to visiting vehicles.
Another Spacewalk Remains Under Consideration
NASA is also planning a fourth spacewalk for Tuesday, Sept. 1. That excursion would include connecting power-channel cables and data-relay systems as part of continuing station maintenance.
The exact objectives could change depending on the outcome of the Aug. 25 spacewalk. If Menon and Adenot are unable to replace the Harmony retroreflector, NASA said that task would become the primary objective of the Sept. 1 excursion.
The agency will determine whether the early September spacewalk is required after the space-to-ground antenna installation is completed.
Station Crew Prepares for Complex Robotics Operations
Preparation for the Aug. 25 excursion has involved other members of the Expedition 75 crew. NASA station commander Jessica Meir and flight engineer Jack Hathaway joined Menon and Adenot for detailed reviews of spacewalk procedures and robotic-arm operations.
Meir and Hathaway are expected to assist the spacewalkers while they enter and exit their spacesuits. During the excursion, Meir will monitor the astronauts outside the station and support Hathaway as he operates Canadarm2 with Menon attached to the robotic arm.
The crew has also coordinated the planned sequence with mission controllers on Earth, reviewing both spacewalking procedures and the robotic movements needed to transport the replacement antenna safely around the exterior of the station.
Science Continues Alongside Spacewalk Preparations
Despite the intensive preparations, Expedition 75 crew members continued scientific investigations and station maintenance. Meir participated in a study examining relaxation techniques intended to reduce stress and improve sleep during long-duration spaceflight.
Hathaway photographed growing three-dimensional colloidal crystal samples for a space manufacturing investigation, while Menon and Adenot performed maintenance on life-support and communications equipment.
Roscosmos crew members also continued research and maintenance activities. Anna Kikina completed a treadmill fitness assessment while electrodes monitored her heart rate and later assisted Pyotr Dubrov with Earth-observation equipment designed to acquire visible and near-infrared images of geographic features across Europe and Asia. Andrey Fedyaev worked on station plumbing and ventilation systems.
Maintaining a Critical Orbital Laboratory
The Aug. 25 spacewalk highlights the continuing maintenance required to keep the International Space Station’s communications, navigation and supporting infrastructure operational. Completing the antenna installation will restore the spare system for high-speed communications, while the optional retroreflector replacement could strengthen navigation support for spacecraft visiting the orbital laboratory.
The outcome of the excursion will also determine NASA’s plans for the proposed Sept. 1 spacewalk as Expedition 75 continues a combination of station maintenance, technology operations and scientific research in low Earth orbit.