1.2 Unique Requirements of Space Telerobotics

	the Surveyor 3, 5, 6, and 7 missions in 1961 and 1968.
	the Viking 1 and Viking 2 missions in July and September of 1976.
	the Soviet Lunakhod 1 and 2 missions in 1969 and 1970.
	the Space Shuttle Remote Manipulator System (RMS) first flown in 1981.

A comparison between these devices and state-of-the-art terrestrial telerobots reveals the challenges inherent in space deployment and operations of advanced telerobotic systems. Current terrestrial robotics can be characterized as:

	limited to industrial manufacturing
	preprogrammed control
	precisely structured environments
	single, highly repetitive tasks
	heavy, rigid devices.

Teleoperators, systems in which a human exercises direct manual control of manipulators, have an advantage over robots in other situations because of the difficulty of preprogramming reactions to all of the contingencies that may occur during a task. Current terrestrial teleoperation can be characterized as:

	developed for use in undersea and nuclear environments
	limited to real-time manual control
	used in semi-structured environments that are hostile to humans
	non-repetitive tasks
	limited maintainability and considerable backlash.

Terrestrially, teleoperators are currently the choice for tasks which are not done sufficiently often to amortize the cost of programming a robot, tasks in which the environment cannot be sufficiently controlled to permit robot operation, tasks in which sufficient manual dexterity, sensing, and artificial intelligence is not yet available in robots, and tasks in which a human operator is warranted because of the cost of a possible failure of a robot is too high.

By comparison, space telerobotics technology requirements can be characterized by:

	need for both teleoperation and automated control
	semi- to unstructured environments
	non-repetitive tasks
	incomplete model of the task environment
	variable time delay between operator and manipulator
	dexterous, lightweight, and flexible manipulators
	complex kinematics and dynamics
	new locomotion mechanisms
	minimal and simple servicing of the device
	hostile environment of thermal gradients, radiation, vacuum, variable lighting, and incomplete data to visualize the task
	need to recover from unplanned events, including system faults and errors.

In summary, the next generation of space telerobotics must be far more flexible in responding to unforeseen events than the current generations of terrestrial robots and teleoperators.

To advance the state-of-the-art of space telerobotics to be equivalent to, and even surpass, terrestrial teleoperators and robots is a significant challenge. The concept of telerobotics encompasses both robotics and teleoperation, seeking to unify these two technologies in such a way that the advantages of both are magnified and the limitations of both are minimized. Thus a telerobot is more capable than either a robot or a teleoperator, and is able to perform a larger class of tasks than can be accomplished by either.

This added power and flexibility is needed to free scarce human time from a myriad of space operations tasks that are dangerous, repetitive, or simply non-interesting. It is important to note that the emphasis of this program, however, is not on eliminating or minimizing the need for humans in space exploration, but rather to find the right cooperative mix of human and automated agents for any given set of mission goals.

Space operations require the ability to work in an environment which is not well defined and which is not controllable, unlike a factory environment. Therefore, telerobotic systems with local and remote teleoperation capabilities are attractive approaches to providing remote manipulation and mobility to augment the capabilities of space suited astronauts. Remote space operations often involve some communications time delay so that terrestrial teleoperation techniques are inadequate. In addition, the scarcity of human resources in orbit makes the full automation of routine manipulative tasks attractive. Also, robotic control of some aspects of tasks (such as keeping a sensor an exact distance from a surface being inspected) is far superior to human control capabilities with teleoperation. Thus, telerobotic systems with robotic capabilities present advantages to certain applications.

The Telerobotics Program is designed to develop a suite of telerobotic capabilities for remote mobility and manipulation, by merging robotics and teleoperations capabilities and creating new telerobotics technologies. To instill potential user confidence in telerobotics, the program actively supports the conduct of a number of terrestrial demonstrations leading to promising space applications. These demonstrations, which are important milestones within individual program tasks, demonstrate the developed capabilities in realistic terrestrial scenarios simulating space conditions. Such demonstrations are also used to identify the telerobot's role in the entire mission, the tradeoffs with alternative solutions, and the technological limitations in achieving required performance.

Applications of space telerobotics technology which have been identified as opportunities for the program include satellite and space system servicing, remote operations on planetary and Lunar surfaces, and robotic tending of scientific payloads. The program is structured to support these types of applications and has selected sets of capabilities to be targeted for development and demonstration to prove the utility of telerobotics in these applications.