The International Space Station (ISS) has multiple robotics systems in place, ranging from the robotics allowing for the solar panels to always face the sun to Canadarm2 that can help dock spacecraft. Robotics are important on the space station because they allow the station to continue to operate and supplies to be delivered from unmanned spacecraft. The most interesting robotics on the station are the robotic arms.
Canadarm2 is a robotic arm that is able to attach itself to other objects or to the station. Canadarm2 is able to do this because the end of the robotic arm contains cables that tighten to ensure a strong grip. This robotic arm is the successor to the Canadarm, which was used on the space shuttles.
Dextre is a multipurpose arm that is able to help astronauts on the space station. Dextre is able to do a variety of tasks such as inspect the surface of the space station, install and replace small pieces of equipment, replace batteries, and replace defective components on the station, along with other functions. Dextre can ride on Canadarm2 or be brought by the Mobile Base System to the required workspace.
Mobile Base System
The Mobile Base System travels up and down the main trusses of the ISS to help move Canadarm2 and Dextre around. It also pulls carts used to transport equipment to different worksites on the space station.
The Sterla cranes are cranes used on the Russian segment of the ISS that assist spacewalks and move objects. The cranes are large enough that they could span the entire Russian segment. These cranes are very similar to the cranes used on the Mir space station.
Japanese Experiment Module Remote Manipulator System
The Japanese Experiment Module Remote Manipulator System on the space station’s Japanese Experiment Module, called Kibo, consists of two robotic arms. The Main Arm is 10 meters long and handles large objects. The Small Fine Arm is two meters long and is used for smaller objects.
Docking Spacecraft With the Assistance of Robots
None of the U.S. spacecraft that currently go to the ISS have automatic docking (with the exception of the Dragon 2), meaning they have to basically park in front of the station and wait for a robotic arm to latch on and guide the spacecraft to dock with the station. However, with new more advanced spacecraft on the way, this feature of robotic arms may no longer be needed.
The use of robotics on the ISS enables many tasks on a variety of levels. Without robotics on the ISS, many spacewalks and repairs would not be possible, which is why it is important to have several different types of robotics on the station.
The SpaceX CRS 18 Mission and How It Used Robotics
On July 27, 2019, the Dragon spacecraft arrived in a parking orbit by the ISS. Canadarm2 was slowly brought toward the Dragon spacecraft and finally attached itself through the control of the astronauts onboard the space station. After Canadarm2 was connected to the Dragon, it directed the spacecraft to the ISS for docking.
The use of robotics on the ISS is the only way that cargo can be remotely brought to the space station until Starliner and Dragon 2, which will both have automatic docking, are in service.
How Astronauts and Robotics Interact
Robotics are an important part of the ISS that requires the work of the astronauts. In the case of SpaceX CRS-18, when the Dragon spacecraft came into a parking orbit with the space station, NASA astronauts Nick Hague and Christina Koch had to control the robotic arm and attach it to the Dragon spacecraft. Once there was a secure connection, the astronauts controlled Candarm2, pulling the spacecraft toward the hatch on the ISS. Once the Dragon was aligned, Hague and Koch brought it toward the hatch. When the Dragon was finally docked, the crew opened the hatch. Although the robotic arms on the ISS are advanced and are able to operate in the vacuum of space and grab onto spacecraft, they require astronauts to guide them to their target.
Learn more in additional posts in the “The ISS Engineering Feat” series on ISS design, power and cooling, and solar array repair.