Robotics Technology

Robotics Technology

The word "robot" was coined in 1934 by the Czech playwright Karel C apek from the Czech word robota, meaning "compulsory labor." While this original meaning still applies to most Earth-bound robots, robots in space have broken through the tedium to become great explorers. They work in environments that may be harmful to humans or in situations where sending a human crew would be too costly. They have been sent as advanced guards to measure the temperature, evaluate the atmosphere, and analyze the soil of other worlds to determine what human explorers can expect to find.

What, exactly, is a robot? A broad definition considers any mechanism guided by automatic controls to be a robot; a very narrow definition requires a robot to be a humanoid mechanical device capable of performing complex human tasks automatically. Robots in space have fallen somewhere in between these extremes. They generally involve a mechanical arm—resembling part of a human, at least—attached to a stationary planetary landing module or to a mobile rover that must perform complex tasks, such as recognizing and avoiding dangerous obstacles in its path. But the evolution to humanoid robots is well under way with the Robonaut being developed by the National Aeronautics and Space Administration (NASA).

Early Space Robots

The first robot in space was a motor-driven mechanical arm equipped with a scoop on the Surveyor 3, which landed on the Moon on April 20, 1967. Acting on signals sent from engineers on Earth, the arm extended and the scoop dug four trenches in the lunar soil, up to 18 centimeters (7 inches) deep. It then placed the samples in front of a camera for scientists on Earth to see. Later Surveyor missions carried analytical instrumentation to determine the chemical composition of the soil samples.

Following the successful human Moon landings that began in 1969 with Apollo 11, NASA began to prepare for piloted missions to Mars. They launched two spacecraft called Viking 1 and Viking 2, which landed on Mars in 1976 on July 20 and September 3, respectively. The Viking landers transmitted pictures of the rock-strewn, rusty-red landscape of Mars back to Earth for the first time. Because there had long been speculation about life on Mars, the Viking landers carried three biological experiments onboard. When the robotic arm of Viking 1 put a sample of the Martian soil into one of the experimental chambers, an excessive amount of oxygen was generated—a possible indication of some form of plant life in the soil. But, to the dismay of the scientists, when the same experiment was performed by Viking 2, no signs of life were found. The question of whether there is life on Mars remains unanswered.

A different type of robot called an "aerobot" was used by Soviet and French scientists to analyze the atmosphere of Venus as part of the Vega balloon mission in 1985. Two Teflon-coated balloons (aerobots) carrying scientific instrumentation floated through the thick Venusian atmosphere for forty-eight hours while researchers recorded temperature, pressure, vertical wind velocity , and visibility measurements. Separate landing modules carried analytical instrumentation to determine the composition of the atmosphere and of the surface on landing. More advanced aerobot technology is being developed for NASA's Mars Aerobot Technology Experiment, scheduled for April 2003.

Space Shuttle-Era Robots

The space shuttle was developed as a reusable spacecraft to replace the costly one-time-use-only vehicles that marked the Apollo era. On its second mission in November 1981, astronauts aboard the space shuttle Columbia tested the Remote Manipulator System (RMS), a robotic arm located in the cargo bay. The RMS is 15 meters (50 feet) long 38 centimeters (15 inches) in diameter and weighs 411 kilograms (905 pounds). It has a shoulder (attached to the cargo bay), a lightweight boom that serves as the upper arm, an elbow joint, a lower arm boom, a wrist, and an "end effector" (a gripping tool that serves as a hand) that can grab onto a payload . The RMS was designed to lift a satellite weighing up to 29,500 kilograms (65,000 pounds) from the payload bay of the shuttle and release it into space. It can also retrieve defective satellites in orbit for the astronauts to repair. Perhaps the greatest achievement of the RMS has been the retrieval and repair of the Hubble Space Telescope (HST), whose initially flawed primary mirror produced blurry pictures. After it was hauled in by the RMS and repaired using corrective optics in 1993, the HST began delivering the high-quality photographs that astronomers had long awaited.

After two decades of debate about the need to explore Earth's nearest neighbor in the solar system, the Mars Pathfinder landed on the Red Planet on July 4, 1997, and deployed a six-wheeled robotic rover called Sojourner to explore the terrain. Standing only 30 centimeters (1 foot) tall and resembling a rolling table with its flat solar panels facing skyward to soak up energy from the Sun, Sojourner roamed short distances to take pictures of interesting rock formations. It used two stereoscopic cameras mounted on its front to see the terrain in three dimensions, just like we do with our slightly separated stereoscopic eyes. A laser beam continuously scanned the area immediately in front of Sojourner to avoid collisions with objects the cameras might have missed. Sojourner analyzed the chemical composition of fifteen rocks using its alpha proton X-ray spectrometer . NASA plans to land a pair of advanced rovers on Mars in 2003.

Robonaut and Beyond

Engineers are starting to think of robots on a more human scale again. Since the space shuttle and the International Space Station are designed on a human scale, having robots built to the same scale would be advantageous in working on these spacecraft. NASA is currently developing the Robonaut, a humanoid robotic astronaut about the size of a human astronaut, with a head mounted on a torso, a primitive electronic brain that allows it to make decisions relating to its work, four cameras for eyes, a nose with an infrared thermometer to determine an object's temperature, two arms containing 150 sensors each, and two five-fingered hands for dexterous manipulation of objects. It will work alone or alongside human astronauts on space walks to build or repair equipment.

Robotics engineers are also working on a personal satellite assistant, which is a softball-size sphere that would hover near an astronaut in a spacecraft, monitoring the environment for oxygen and carbon monoxide concentrations, bacterial growth, and air temperature and pressure. It will also provide additional audio and video capabilities, giving the astronaut another set of eyes and ears.

see also Exploration Programs (volume 2); Robotic Exploration of Space (volume 2).

Tim Palucka

Bibliography

Asimov, Isaac, and Karen A. Frenkel. Robots: Machines in Man's Image. New York:Harmony Books, 1985.

Masterson, James W., Robert L. Towers, and Stephen W. Fardo. Robotics Technology. Tinley-Park, IL: Goodheart-Willcox, 1996.

Moravec, Hans. Robot: Mere Machine to Transcendent Mind. New York: Oxford University Press, 1999.

Thro, Ellen. Robotics: The Marriage of Computers and Machines. New York: Facts on File, 1993.

Yenne, Bill. The Encyclopedia of U.S. Spacecraft. New York: Exeter Books, 1985.

Internet Resources

Aerobot. National Aeronautics and Space Administration. <http://robotics.jpl.nasa.gov/tasks/aerobot/background/when.html>.

Robonaut. National Aeronautics and Space Administration. <http://vesuvius.jsc.nasa.gov/er_er/html/robonaut/robonaut.html>.

2003 Mars Mission. National Aeronautics and Space Administration. <http://mars.jpl.nasa.gov/missions/future/2003.html>.