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The Canadarm robot has boosted national pride and showcased Canadian technology for more than two decades. In space, the arm emblazoned with a Canada logo and flag first twitched to life aboard a shuttle in 1981. We look back at the arm grabbing errant satellites, helping fix the Hubble telescope and shaking hands with its robotic cousin, Canadarm2.

MDA is involved in the area of satellite missions providing a variety of solutions to many customers around the world. MDA is currently developing Canada's next generation of SAR Earth Observation satellite RADARSAT-2. The company is increasingly getting involved in a new generation of low-cost, innovative small satellite missions providing high value operational systems to clients in areas such as earth observation, information delivery, surveillance of space and space science.

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MDA engages in extensive Research and Development to maintain and advance our leading position in space robotics. We undertake R&D in-house and through a network of relationships with universities and research institutions to provide our customers with innovative solutions at the leading edge of technology.

The Canadarm is a remotely operated appendage that can be used onboard any space shuttle to perform unique and difficult missions, that no human or humans could perform alone. So, like any invention, the Canadarm helps man to exceed his natural limitations. The Canadarm is currently onboard the space shuttle Columbia ( Oct. 16, 2000 ) where it will be used to carry out its usual tasks of launching satellites, capturing satellites in orbit for repair, and taking readings of the space shuttle itself to check for any problems before re-entry.

The Canadarm was designed and manufactured in Canada at Spar Aerospace Limited, based in Ontario. This company has a fine history of relations with NASA, in fact, the American space agency is contracting Spar Aerospace to construct several more appendages, just like the Canadarm. This contract can only serve to strengthen the bond between Canada and NASA, making it possible for Canada to make its' name known to the rest of the world as a pioneer in the endeavors of science.

The Canadarm was invented, like any other thing, to fulfill a need. The need or problem came from NASA, they needed a cheap, safe and effective way of maneuvering and manipulating large pieces of equipment and payloads, during missions, 200 km above the Earth. They turned to Spar Aerospace Limited ... and they weren't disappointed. The Canadarm made its' premier in 1981.

An artists' rendering of the Canadarm attached
to the International Space Station.
Note: The I.S.S. is due to be up and running in 2006.

The Canadarm is perhaps one of the most well-known Canadian accomplishments in space. Designed and built by the Canadian firm Spar Aerospace Ltd., the Canadarm was a gift from Canada to NASA's space shuttle program. The first Canadarm, technically called the SRMS (Space shuttle Remote Manipulator System), flew on the shuttle Columbia in 1981. NASA then bought Canadarms to equip the rest of the shuttle fleet.

Although the Canadarm flies on board the shuttle, its primary function involves satellites. The Canadarm has consistently and successfully been used to release satellites into orbit, retrieve them if they malfunction, and aid in their repair.

When the shuttle carries satellites into space, the Canadarm reaches into the Payload Bay of the shuttle and lifts the satellite out. After the satellite has been checked and confirmed ready for release, the Canadarm releases the satellite and the shuttle maneuvers away.

So that the Canadarm can grip the satellites, a special foot-long metal prong is attached to the satellite's bus (commonly known as the body of the satellite). This prong is called a grapple fixture. Inside the end of the Canadarm are three snare wires. Small motors constrict the wires, wrapping them tightly around the grapple fixture. The wires are then retracted, and the satellite is pulled snugly against the end of the arm. The Canadarm is unable to grasp older satellites because they were not fitted with grapple fixtures when they were originally launched.

Besides routine satellite launching jobs, the Canadarm is also used to repair satellites in trouble. The Canadarm has saved several very costly satellite projects from disaster.

The first on-orbit repair job was of NASA's $235 million Solar Max satellite. Solar Max was launched to study solar flares. After 10 months, three fuses blew in the satellite causing several of the satellite's instruments to fail.

On the space shuttle Challenger flight in 1984, astronaut George Nelson was supposed to recapture the satellite from a Manned Maneuvering Unit (MMU). When he reached Solar Max, however, he found that the special tool he had been given to grapple the satellite did not fit! Fortunately, Mission Commander Robert Crippen, with the last of the orbiter's maneuvering fuel, was able to bring the orbiter close enough to the satellite so that the Canadarm could grab it.

Once Solar Max was safely in the Payload Bay, the Canadarm once again came to the aid of the astronauts. By standing with their feet clamped to a work platform fixed to the Canadarm, astronauts could be moved easily and accurately to the parts of the satellite needing repair. This also left their arms free for doing repair jobs.

Thanks to the Canadarm, Solar Max could then be redeployed into orbit for several more years of profitable scientific research.

Since the Solar Max rescue mission, the Canadarm has been essential to many satellite repair jobs. For example, the Canadarm was twice used to recapture and then redeploy the Hubble Space Telescope. After extensive repairs in 1993 and 1997, the Hubble telescope was able to take clear and precise pictures of stellar phenomena vast distances away from the Earth.

The Canadarm is now routinely employed to make satellite launch, retrieval, and repair easier and more efficient tasks.

SPAR, one of Canada's leading advanced technology companies, is headquartered in Toronto and has 2,800 employees in North America, Europe and the Pacific Rim. It is building on its proud heritage as Canada's premier space company and is keenly focused on the profitable growth of its aviation and robotic services and space communications products businesses. SPAR is primed to become the absolute best space technology company around the globe.

After eight years of hard work, the Canadarm was first launched aboard STS-2, the second shuttle flight, on November 12th, 1981, as one of the most high-profile contributions to the NASA space shuttle program.

The first Canadarm nearly didn't make it into space on this flight. The shuttle vibrated so badly during the first launch that NASA had to find some way to keep the rocket boosters' shock wave from damaging the arm before it got off the Earth. A US $2-million dollar water-deluge system was set up at the base of the launch pad to spray more than a million litres of water into the rocket's exhaust, reducing the shock wave by 75%.

On Friday, November 13th, the arm was deployed for the first time.When it was first deployed, the arm displayed no power and no signal, but it turned out to be the astronaut, not the arm that was jinxed by the date . When astronaut Richard Truly went to check the switches, normally his feet were on the floor but this time his feet were on the ceiling and he was flicking switches in the wrong direction . The mistake was soon corrected, and the arm worked perfectly.

The arm was named 'the Canadarm' by Larkin Kerwin, head of the National Research Council, at the ceremony during which NASA officially accepted the arm. Larry Clarke, then president of Spar Aerospace, said that 90% of the arm is Canadian content, and at the initiative of Dr. Art Hunter (Canadarm Project Manager ) and Bruce Aikenhead (Deputy manager of the program) it was arranged that the arm should carry the word "Canada" as a symbol of its Canadian heritage.

The arm was successfully run through many tests on subsequent shuttle flights, including critical manoeuvres such as operation of the braking system and the deployment and replacement of a payload from the cargo bay. Arm operator Jack Lousma reported that the arm was "as close to perfect as it could be. If there are any surprises here, they're all pleasant. I am really impressed with that piece of machinery." His partner, Gordon Fullerton, added that the arm "performed exactly like they said it would. Every time there was a little doubt about how it would operate, it actually turned out to be easier or quicker or smoother... Canada should be proud of the technology that produced it."

MANIPULATOR ARMS FOR SPACE SHUTTLE AND ISS

The requirement for installation of a manipulator (grasping arm, derived from the Latin "manus" for hand) in the payload bay of the Orbiter was identified as far back as the preliminary stages of planning for the US Space Shuttle transport system. Only with the aid of such a mobile gripping device, at the time still referred to as a "crane", would it be possible to complete the planned tasks in orbit, i.e. the release and retrieval of satellites and also the provision of support for repair and assembly work.

It was not long before the functional requirements for such a Payload Deployment and Retrieval System (PDRS) were defined in more detail and a corresponding invitation to tender was issued. Despite all endeavours, none of the US companies active in the industry was able to even approach satisfying the conditions, so that the contract to develop the crane arm went to Canada, to Spar Aerospace Ltd. of Brampton, Ontario. This resulted in what was (and still is) a unique situation, in which one of the most critical subsystems of the US Space Shuttle system originated not from the USA but from another country.

A Space Robotics Division was established at Spar Aerospace especially for the project, and the company's engineers created a masterpiece in only a relatively short development and trial period. They created a 16-part manipulator system, henceforth better known under the name of Canadarm, that actually resembles an arm, with shoulder, upper arm, elbow, forearm, wrist and hand. The entire carbon fibre structure is 15.2m long, has a diameter of 38cm and, in its original form, was able to move loads of up to 29,484kg.

The Canadarm is attached at the "shoulder", on the left-hand side of the Shuttle Orbiter's loading bay. Two TV cameras, one at the elbow and one at the wrist joint, enable the responsible mission specialist to follow every movement and control the manipulator from the upper rear flight deck.

The manipulator in turn is controlled by means of two joysticks. The joystick commands are converted into commands by the general-purpose Orbiter computer, and feedback in response to control inputs is received back within 80ms. In this way the arm can be moved 6cm per second with a load and 60cm per second without.

The Canadarm's "hand" is not actually very hand-like even though the original idea had been to implement a grasping device that would be similar to a hand. However, it transpired during trials that, for example, it would not have been possible to securely grasp and move satellites weighing several tonnes with such a device. Finally, after several long series of tests, an "end effector" was developed, an ingenious device that yet functions in a quite simple manner.

The open end of the effector is placed over a grapple probe (knobbed pin) that is bolted onto the payload. When the probe comes into contact with a contact plate, three motor-driven steel cables draw together in the opposite direction so that the object is enclosed and thus locked in position. Release of the load entails the opposite procedure. For certain tasks, however, a special effector can also be mounted. For example, this might transmit electrical power to the target object.

Five Canadarms have been built and installed in the NASA Shuttles. Of these, one was lost in the tragic Challenger accident in January 1986. All the others have performed flawlessly since they were first deployed from the second Shuttle mission in November 1981, and have never even developed a single fault. In the meantime all the arms have been upgraded and can now convey loads of up to 266,000kg in zero-gravity.

The excellent experience that NASA astronauts have had using Canadarm has logically flown into the design of the successor system, which is to be installed on the International Space Station, under the name of "Canadarm 2". In this three-part manipulator, the Canadian engineers are delivering a veritable masterpiece.

Consisting of the Mobile Servicer Base System (MSBS), Remote Manipulator System (RMS) and Special Purpose Dextrous Manipulator (SPDM) subsystems, the multi-function arm will in future be able to move on rails in a direction transverse to the direction of travel, along the grid structure of the station, and thus to also reach points some way away.

However, the MSBS rail car will probably not be delivered to the station until ISS Assembly Flight UF-2 in April 2002, whereas the RMS arm has meanwhile already been installed on the US Destiny laboratory module, in April 2001. Finally, the SPDM is scheduled for October 2003 during mission UF-4, following which the manipulator system will be fully operational.

The designers attached particular importance to improving the manipulator on the future SPDM still further. As well as an improved end effector, this manipulator has additional claws enabling small objects to be held, plus two colour television cameras which take pictures directly of the site being worked on. Two additional cameras on the elbow of the RMS transmit pictures of the environment to the operator of the arm, who, once the station has been fully assembled, will have his workstation in one of the domes on the US Node 3 module.

This will enable the duty astronaut to carry out complicated assembly work even in locations which he cannot see directly. Thus, in the truest sense, Canadarm 2 is the extended arm of the station crew for the transport of large payloads, even if this is "only" along the grid structure at whose ends the enormous solar-powered booms of the station are attached.

From there, the 17.6m long arm can reach virtually every point of the station that it needs to reach, but not quite all. For this reason it will be supplemented by several small manipulators, such as the Russian Strela, the European Robotic Arm (ERA) and one American and one Japanese device. Each of these has a particular job to perform, but none of them is a patch on the Canadarm.

The people from NASA were skeptical. Should they entrust one of the most crucial aspects of the new shuttle program to a relatively untested engineering team from Canada? Their decision, in 1975, to do just that has meant that Canadians are responsible for one of the most significant advances in space engineering—the Canadarm.

Measuring 15.2 m (50 ft) in length with an earth weight of 410 kg (905 lbs), one of the Canadarm's most impressive engineering achievements is its ability to capture a free-flying payload in a zero gravity environment. The slightest contact with an object in space, regardless of size, will send it spinning away. The engineering team at Spar Aerospace developed a special grappling system for this unique environment. It consists of snares and a pin. The pin is attached to the payload and the snares then close around it, much like a high-tech lasso. The arm can then move the payload as required. This elegant design was created specifically for the arm and has been sold to the Americans and the Japanese.

The team also engineered a very sophisticated control system. Astronauts had to be able to control a 50-foot arm over a wide range of commands and for a wide range of payload sizes. Operating the Canadarm may mean moving it very accurately and slowly over a distance of millimetres or it may mean moving it precisely over several metres at a very high speed. This isn't possible if the arm and its joints have too much flex so the team designed an anti-backlash device within the joints which has resulted in zero backlash.

Safety is preeminent in the minds of SPAR's engineers. There is no room for error in space. Virtually every system in the Canadarm has built-in redundancy while the arm itself automatically performs built-in safety checks. This has all been done without increasing its weight or size. During more than 50 missions and after 7,000 orbits around the earth, the Canadarm has never malfunctioned. Indeed, it is used to help solve other problems on the shuttle, everything from knocking ice off the fuselage of the Orbiter to fixing the Hubble Space Telescope. And of course, it is instrumental in assembling the new international space station. The Canadarm is truly one of the greatest Canadian engineering achievements.

Hubble Telescope and the Canadarm

By Lisa Cavion

The Hubble Space Telescope was one of the most ambitious and exciting space observation projects ever launched. At the same time, it was also one of NASA's greatest embarrassments.

Deployed by the Canadarm in April, 1990, Hubble Space Telescope was heralded as a huge step forward in the scientific understanding of the universe around us. Unfortunately, Hubble first had to teach us a lesson in optics.

The largest on-orbit astronomical observatory ever built, Hubble was constructed to answer questions about the origin of the universe, the evolution of galaxies, and the existence of other planets. Scientists believed that Hubble would be able to produce images of objects 14 billion light years away. Unclouded by earth's atmosphere, it should have been able to peer into distances up to 10 times greater than earth-based telescopes.

That is, of course, if it had been able to see at all.

Not that the satellite was exactly blind as a bat. Unfortunately, Hubble's first pictures were dismayingly blurry. Despite its lofty position, the space telescope could see no better than its earth-bound cousins.

The telescope’s myopia came as a shock to everyone. What could possibly be done with a telescope that can't see? Well, you fix it.

The Canadarm was called on for every aspect of the rescue and repair effort -- capturing the satellite, securing in the shuttle cargo bay, ferrying around the astronauts who repaired it and, finally, redeploying it into space. As it has done on many other occasions, the Canadarm became an essential support player, once again providing the means for human ingenuity to salvage a major triumph from the threat of disaster.

Hubble looks like an aluminum foil-wrapped, rail-road-car sized cylinder, with "wings" (the solar arrays that collect energy from the sun) and antennas extending from the body of the telescope. Outside the satellite itself is the support systems module, which contains the spacecraft and antenna controls and houses the electrical power and tool support systems.

Hubble also contains several advanced scientific instruments including a Wide Field/Planetary Camera, a Faint Object Camera, a Goddard High Resolution Spectrograph, a High Speed Photometer, and the three fine guidance sensor systems. These instruments, which are capable of peering into deep space, are used to search for planetary systems, quasars and black holes; they are also able to measure ultraviolet radiation emanating from distant objects and the changing position of heavenly bodies.

Hubble also contains the mirrors that allow it to "see" distant objects. Its 2.4-metre primary mirror, made of precision-ground glass and aluminum, is housed in the main body of the telescope.

Light travels from outer space into the telescope and hits the primary mirror, which reflects the light to a 32.5-cm secondary mirror. From there, the light beam narrows and intensifies before being passed back through a hole in the centre of the primary mirror onto the scientific instruments.

Unfortunately, by June, 1990, just two months after a picture-perfect launch, a flaw was discovered in Hubble's primary mirror -- it was suffering from "spherical aberration", an optical defect that made it impossible to focus starlight sharply. Hubble produced fuzzy halos and blurred objects instead of sharp, clear images.

The two mirrors must be in precise alignment for the images to be in focus. Without properly-focused mirrors, Hubble is a little like a giant, orbiting handy-man without glasses -- it's got plenty of great equipment, but can't quite see what it is supposed to be working on.

The primary mirror, supposedly the smoothest large mirror ever made, was too flat at the edge by an amount equal to 1/50th the width of a human hair. Although this sounds insignificant, it is a huge defect in optical terms. As it turned out, the company manufacturing Hubble's primary mirror had ground the mirror into the wrong shape, using an incorrectly assembled testing device.

Of course, once launched, the mirror couldn't be replaced or repaired. Fortunately, engineers at the Space Telescope Science Institute in Baltimore, Maryland, came up with an alternate solution. They decided to remove one of the telescope's instruments and install a box containing a mechanical arm holding coin-sized corrective mirrors between the primary mirror and the instruments. In short, Hubble would become the first telescope to get a pair of eye-glasses!

The optical correction device, known as COSTAR, remedies the focus problem for three of Hubble's five main scientific instruments. Luckily, by the time the repair mission got underway, many of Hubble's other instruments, which had been designed for in-flight maintenance, were coming to the end of their natural life-spans. They were simply replaced with instruments designed to take into account the main telescope's defect.

Even though Hubble was designed for maintenance in space, the repair effort was still one of the most challenging repair missions NASA had ever attempted. The task required an unprecedented five spacewalks totalling 30 hours and involved a series of the most complex tasks ever undertaken in orbit.

Once the shuttle Endeavour was in position, the Canadarm reached out to grab the 12.5 ton satellite, as it had done before with other satellites and place it on a rotating service platform at the rear of the ship's cargo bay. Over the next five days, the Canadarm was used extensively as a work platform, moving the arm-mounted spacewalkers and supporting them in position while they installed the COSTAR, the new solar arrays, the pointing system, one of Hubble's two main cameras, and even new fuse plugs.

The crew, which collectively had logged 400 hours training for the spacewalks in deep-water tanks and virtual reality simulators on earth, performed all the necessary repairs quickly and thoroughly, proving that the Hubble could be serviced on-orbit.

The mission was essential to repair not only the telescope but also NASA's image. "Hubble represents a success that everybody involved takes great pride in. It rejuvenates NASA and makes us feel better about ourselves," said Hubble mission director Randy Brinkley.

Restoring Hubble’s scientific capabilities and the reliability of the satellite, "going to go a long way toward restoring confidence in NASA," said Lori Garver, director of the National Space Society.

Three and a half years ago, I really didn't' believe this thing would ever be pulled off," added Hubble program scientist Edward Weiler.

Thanks to thousands of hours of preparation and training, they did manage to pull it off. Hubble was redeployed by the Canadarm and was back on the job of solving the mysteries of deep space within a few months.

Scientists responded enthusiastically to the telescope's high quality imagery. A December, 1995, National Geographic article described the repaired Hubble telescope as "the modern equivalent of the one Galileo used to prove that the earth revolves around the sun -- a brilliant new device".

"I feel fortunate to have been around at this moment," said C. Robert O'Dell, an astronomer at Rice University in Houston, Texas, who used images taken by Hubble to examine the Orion nebulae.

Hubble is finally doing what it was intended to do; answering -- and asking -- questions about our universe.

The Shuttle Remote Manipulator System -- The Canadarm

MANIPULATOR ARMS FOR SPACE SHUTTLE AND ISS