Education Robot

Following the remarkable successes of the Apollo Moon landings and the Skylab space station program, many space experts began reconsidering the role of humans in space exploration. In a healthy debate on exploration strategies, some experts concluded the goals of the future would be best served by robotic spacecraft. Human space travelers require extensive life support systems. With current propulsive technologies, it would just take too long to reach any destination beyond the Moon. 

Robots could survive long space voyages and accomplish exploration goals just as well as humans. Other space experts disagreed. Humans have an important place in space exploration, they contended. Robots and humans are not interchangeable. Humans are far more adaptable than robots and can react better to the unexpected. When things go wrong, humans can make repairs. This, they pointed out, was demonstrated conclusively during Skylab, when spacewalkers made repairs that saved the mission.

Today, new exploration strategies are at work. The goal is no longer humans or robots. It is humans and robots working together. Each bring important complimentary capabilities to the exploration of space. This has been demonstrated time and again with the Space Shuttle Remote Manipulator System (RMS) robot arm. The arm, also called Canadarm because it was designed and constructed by Canada, has been instrumental to the success of numerous space missions. The 15-meter-long arm is mounted near the forward end of the port side of the orbiter’s payload bay. It has seven degrees of freedom (DOF).

In robot terms, this means that the arm can bend and rotate in seven different directions to accomplish its tasks. Like a human arm, it has a shoulder joint that can move in two directions (2 DOF); an elbow joint (1 DOF); a wrist joint that can roll, pitch, and yaw (3 DOF); and a gripping device (1 DOF). The gripping device is called an end effector. That means it is located at the end of the arm and it has an effect (such as grasping) on objects within its reach. The RMS’s end effector is a snare device that closes around special posts, called grapple fixtures. The grapple fixtures are attached to the objects the RMS is trying to grasp.

On several occasions, the RMS was used to grasp the Hubble Space Telescope and bring the spacecraft into the orbiter’s payload bay. After the spacecraft was locked into position, the RMS helped spacewalking astronauts repair the telescope and replace some of its instruments. During operations, the RMS is controlled by an astronaut inside the orbiter. The RMS actually becomes an extension of the operator’s own arm. Television cameras spaced along the RMS permit the operator to see what the arm is doing and precisely target its end effector. At times, during the Hubble servicing, one of the spacewalkers hitched a ride on the end effector to gain access to parts of the telescope that were difficult to reach. The arm became a space version of the terrestrial cherry picker.