Chapter 4: Mobile Servicing System

One of the robotic systems that may be found on board the International Space Station (ISS) is called the Mobile Servicing System (MSS). It was launched to the International Space Station in 2001, and it plays an important part in the assembly and maintenance of the station. It is responsible for moving equipment and supplies around the station, providing assistance to astronauts who are working in space, cleaning instruments and other payloads that are attached to the ISS, and doing maintenance on the outside of the station. Astronauts get specific training in order to equip them with the skills necessary to carry out these activities with the variety of systems that make up the MSS.

Three components make up the MSS, which are as follows:

On top of the Mobile Transporter cart that is given by the United States and that houses the MRS Base System, the system is able to move along tracks that are attached to the Integrated Truss Structure. Using the Ada 95 programming language, the control software for the system was successfully developed.

For the purpose of the Canadian Space Agency's contribution to the International Space Station, the MSS was designed and constructed by MDA, which was formerly known as SPAR Aerospace and includes units of MacDonald Dettwiler Associates that were formerly known as MDA Space Missions and MD Robotics.

SSRMS stands for the Space Station Remote Manipulator System, which is the official name for this unit.

The second generation arm of the Space Shuttle, which was launched on STS-100 in April 2001, is a larger and more improved version of the first Canadarm that was used on the satellite. When fully extended, Canadarm2 is 17.6 meters (58 feet) in length and is equipped with seven motorized joints. These joints include a hinge like an elbow in the middle, as well as three rotational joints at each of the wrist and shoulder ends. Titanium was used in its construction, and it weighs 1,800 kilograms (4,000 pounds) and has a diameter of 35 centimeters (14 inches). In addition to being able to assist with docking the space shuttle, the arm is designed to handle heavy payloads that can weigh up to 116,000 kilograms (256,000 pounds). Using a movement similar to that of an inchworm, it is able to move end-over-end and is capable of self-relocating to reach many different areas of the Space Station. During this movement, the only thing that can restrict it is the quantity of Power Data Grapple Fixtures (PDGFs) that are present on the station. Through either of the two Latching End Effectors (LEEs) that are positioned around the station, power, data, and video are transmitted to the arm by PDGFs that are located around the station. Through the utilization of the Mobile Base System, the arm is also capable of traversing the whole length of the space station truss.

It is possible for the arm to move any object that has a grapple fixture attached to it, in addition to moving itself around the station. In the process of building the station, the arm was utilized to move massive segments into their proper positions. It is also capable of capturing unpiloted ships such as the SpaceX Dragon, the Cygnus spacecraft, and the Japanese H-II Transfer Vehicle (HTV). These vessels are fitted with a conventional grapple mechanism, which the Canadarm2 employs in order to grab and dock the spacecraft. An additional function of the arm is to unberth and release the spacecraft after it has been employed.

When on-board operators glance at the three LCD panels that are located on the Robotic Work Station (RWS), they are able to see what they are doing. There are two RWS units on the MSS; one is located in the Destiny module, and the other is located in the Cupola. The MSS is only under the control of a single RWS at any given moment. Each of the two sets of control joysticks that are included with the RWS are referred to as the Rotational Hand Controller (RHC) and the Translational Hand Controller (THC). The Display and Control Panel (DCP) and the Portable Computer System (PCS) laptop are also included in this category.

In recent years, the majority of robotic operations have been commanded remotely by flight controllers located on the ground at the Christopher C. Kraft Jr. Mission Control Center or from the John H. Chapman Space Centre, which is operated by the Canadian Space Agency. When compared to on-board crew operators, operators are able to work in shifts to complete goals with greater flexibility, but at a slower pace. This allows for greater flexibility. During time-sensitive activities, such as visiting vehicle captures and extra-vehicular activity supported by robotics, astronaut operators are responsible for performing their duties.

A piece of orbital debris struck Canadarm2 at some point before to the 12th of May, 2021, causing damage to its thermal blankets as well as one of the booms located on the spacecraft. The functioning of the device appeared to be unaffected.

Additionally, Canadarm 2 will be of assistance in berthing the Axiom Space Station modules to the International Space Station.

There are two LEEs inside of Canadarm2, one at each end. The grappling fixture shaft is caught by three snare wires that are attached to a LEE. An additional LEE is now stationed aboard the Payload ORU Accommodations (POA) unit of the Mobile Base System. For the purpose of temporarily holding heavy ISS components, the POA LEE is utilized. Additional information is available on the Special Purpose Dexterous Manipulator (SPDM), which is often referred to as "Dextre" or "Canada hand." There have been six LEEs produced and deployed in a variety of locations across the International Space Station [citation needed].

Additionally known as "Dextre," the Special Purpose Dexterous Manipulator is a smaller two-armed robot that has the capability to attach to Canadarm2, the International Space Station, or the Mobile Base System. The arms and the power tools that come with them are able to perform delicate assembly jobs and change Orbital Replacement Units (ORUs), which are currently being handled by astronauts while they are on spacewalks. Despite the fact that Canadarm2 is capable of moving about the station in a "inchworm motion," it is unable to carry anything with it unless Dextre is attached to it. Testing was carried out in the space simulation chambers located at the David Florida Laboratory in Ottawa, Ontario, which is owned and operated by the Canadian Space Agency. The manipulator was brought to the station on STS-123 on March 11, 2008, when it was placed into orbit.

The Mobile Remote Servicer Base System, often known as the MBS, serves as a foundational environment for the robotic arms. During STS-111, which took place in June of 2002, it was added to the station. The Mobile Transporter, which was installed on STS-110 and was designed by Northrop Grumman in Carpinteria, California, is the platform that allows it to glide down tracks on the main truss of the station. The platform is put on top of the Mobile Transporter. In contrast to Dextre, which is unable to relocate on its own, Canadarm2 is capable of moving on its own but cannot carry at the same time. The MBS enables the two robotic arms to move to work areas all along the truss structure and to step off onto grapple fixtures along the way. This capability is made possible by the MBS. Together, Canadarm2 and Dextre have a total mass of 4,900 kilograms (10,800 pounds) when they are coupled to the MBS configuration. MD Robotics was responsible for its construction, and it has a minimum service life of fifteen years, just like Canadarm2.

A Power Data Grapple Fixture is installed in each of the four upper corners of the MBS, making a total of four Power Data Grapple Fixtures. It is possible to use any of them as a base for the two robots, Canadarm2 and Dextre, as well as for any of the payloads that they might be carrying. There are also two places on the MBS where payloads can be attached. The Payload/Orbital Replacement Unit Accommodations (POA) are the first type of accommodation. A device that is quite similar to the Latching End Effectors of Canadarm2 in both appearance and operation is being described here. It is possible to utilize it to park, power, and command any payload that is equipped with a grapple fixture, all while simultaneously freeing up Canadarm2 to perform another task. In addition to it, the MBS Common Attachment System (MCAS) is the other application location. An additional form of connection system that is utilized for the purpose of hosting scientific investigations is this one.

Extravehicular activities are another area in which the MBS provides assistance to astronauts. In addition to a camera assembly, it features foot restraints, handrails, and attachment points for safety tethers, as well as storage areas for tools and equipment. In the event that it become necessary, it is even feasible for an astronaut to "ride" the MBS while it is traveling at a maximum speed of around 1.5 meters per minute. There are translation aids for the crew and the equipment located on either side of the MBS. The MBS and these carts share the same rails for transportation. During extravehicular activities (EVAs), astronauts ride them so that they may transfer equipment and make it easier for them to travel around the space station.

A 15.24-meter (50-foot) boom that is equipped with railings and inspection cameras was added to the end of Canadarm2 on May 27, 2011, in order to facilitate its installation.

The Japanese Experiment Module Remote Manipulator System (JEM-RMS) was presented to the station as a second robotic arm during the Space Transportation System (STS)-124 mission. The primary function of the JEM-RMS is to provide maintenance for the JEM Exposed...