The Future of the Canadarm

The MSS .
The Canadarm's mechanical parts (MDRobotics)

The Space Station Remote Manipulator System (SSRMS) is a new generation Canadarm, the first component of the Mobile Servicing System (MSS) which is scheduled for launch on STS-100 early in the station's assembly sequence. Canadian Astronaut Col. Chris Hadfield will perform three EVA's or space walks to assemble the SSRMS on-orbit.

The station arm will have the new capability to move around the station's exterior like an inchworm. Each end of the arm is equipped with a specialized mechanism called a Latching End Effector (LEE) that can lock on one of many special fixtures, called Power Data Grapple Fixtures (PDGF), then detaching its other end and pivoting it forward. The range of accessibility of the SSRMS will be limited only by the number of PDGF's strategically installed on the station. The LEE is designed to provide power and data signals at both ends of the arm.

Unlike the Canadarm, the SSRMS stays in space for its useful life. This requirement necessitates an innovative design feature which allows astronauts to repair it on-orbit. The SSRMS is built in sections called Orbital Replacement Units (ORU's) which are easily removed and then replaced by either an astronaut or the Special Purpose Dexterous Manipulator.

The SSRMS is equipped with four TV cameras that feed wide and close-up views to the operators of the Canadian-built robotics, and an advanced vision system which has the ability to track payloads, and can sense various forces and moments to ensure smooth movement of payloads. The station arm also has a collision-avoidance capability. Two sets of cameras are mounted on the booms, one set on each side of the elbow joint. The remaining two sets of cameras are on the latching end effectors (one set on each LEE).

The Canadian Invention
Canadarm: one of Canada's greatest achievements (Spar)

Reprinted courtesy of MacDonald Dettwiler Space and Advanced Robotics Ltd.