Launch: Scheduled for 2008

Dextre is an essential tool for maintaining and servicing the space station. With its dual-arm design providing added flexibility, Dextre will remove and replace smaller components on the Station’s exterior, where precise handling is required. It will be equipped with lights, video equipment, a tool platform and four tool holders.

Dextre can perform dexterous tasks by sensing various forces and moments on the payload. In response, it can automatically compensate its movements to ensure the payload is manipulated smoothly.

With its two arms, Dextre will load and unload objects, use robotic tools, attach and detach covers and install various units of the Space Station. It will either be attached to the end of Canadarm2 or ride independently on the Mobile Base System and have Canadarm2 deliver equipment to it for servicing. It also has four cameras that will provide the crew inside the Station with additional views of the work areas.

Like Canadarm2 and the Mobile Base System (MBS), the Special Purpose Dexterous Manipulator will be controlled by the crew inside the International Space Station. This system will allow the crew to perform many of the tasks that would otherwise require an astronaut to perform during a demanding spacewalk.

Dextre is a sophisticated dual armed robot, which is part of Canada's contribution to the International Space Station (ISS). Along with Canadarm2, whose technical name is the Space Station Remote Manipulator System, and a moveable work platform called the Mobile Base System, these three elements form a robotic system called the Mobile Servicing System (MSS). The three components have been designed to work together or independently.

MD Robotics, located in Brampton, Ontario, is the main contractor of the Dextre. The technology behind Dextre is built upon the heritage of its predecessor, Canadarm2. Conceptually the two robots are similar and they both operate with the support of computers; however, their design and purpose are different.

Dextre is a complex robot designed to perform intricate maintenance and servicing tasks on the outside of the ISS. Dextre will carry out delicate work that, so far, could only be accomplished by astronauts during spacewalk activities. In other words, Dextre will provide an alternative to astronauts, considerably reducing the amount of time that they have to venture out of the ISS to perform demanding spacewalks and providing more time for them to perform science on the ISS.

Upon close inspection of Dextre, one notes its resemblance to the human shape: an upper body that can pivot at the waist with shoulders that support two identical arms. Each arm has a total of seven joints, providing an incredible amount of freedom when performing a task. However, Dextre is designed so that only one arm can move at a time in order to avoid self-collision, achieve greater stability and maintain operational similarity with Canadarm2. The greater stability is provided by the immobile arm, which is first commanded to anchor Dextre to an ISS stabilization point. At the tip of each arm, we find a "hand", known technically as the Orbital Replacement Unit/Tool Changeout Mechanism (OTCM). The OTCM consists of a set of parallel retractable jaws, which serve to grip payloads and tools. Each OTCM is also equipped with a retractable motorized socket wrench to mate and demate mechanisms on-orbit, as well as lights and a black & white camera. Dextre lower body is equipped with a pair of pan/tilt colour cameras that allow astronauts aboard the ISS, and engineers on the ground, to monitor the task, which is out of direct eyesight.

A variety of tasks will be performed by Dextre including installation and removal of small payloads such as batteries, power supplies and computers; providing power and data connectivity to payloads; and manipulating, installing, removing and inspecting scientific payloads. A typical task for Dextre is to replace a depleted (100 kg) battery, which involves bolting and unbolting operations as well as millimetre level positioning accuracy to properly align and insert the spare battery within its worksite and properly engage all connectors. This peg-in-the-hole type of task demands a great amount of precision and a gentle touch to avoid binding. To achieve this Dextre has a unique feature which complements its remarkable dexterity: precise sensing of forces and torques at the "hand" and automatic compensation to ensure the payload moves smoothly into its mounting fixture. To illustrate the level of performance of Dextre, here on Earth it could likely be used to insert an item as delicate as a videotape into a video recorder.

Dextre is a very versatile robotic tool. It can work solo, fixed to one of the base points (known as power data grapple fixtures) along the side of the Station or on the Mobile Base System. However, most of the time Dextre will do its work while attached to the free end of Canadarm2 which will manoeuvre Dextre into position next to the payload which requires maintenance along the main truss of the ISS. Astronauts aboard the ISS will operate all of the MSS components from a robotic workstation. As part of mission preparation, astronauts must undergo rigorous training to learn how to operate each component of the MSS. Canadian Space Agency engineers provide this training at the John H. Chapman Space Centre in Saint-Hubert, Quebec.

Dextre is currently going through final testing prior to its launch slated for 2008.