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A robot is defined as a self-controlled device consisting of electronic, electrical or mechanical units that can function in place of a living agent.
Robots play a vital role in exploring the hostile environment of outer space. Besides the Earth, the Moon is the only celestial body that humans have stepped on. However, advancements in research are making it possible for robotic missions to reach space faster and gather more information than humans. Robots don’t get tired, can operate in airless environment and do not get bored or distracted, making them superior to humans in a lot of ways.
Space robots are of various sizes and shapes, which include robot arms, (e.g. the Space Shuttle Remote Manipulator System; rovers - Sojourner; landers - Mars Pathfinder; atmospheric probes - Huygens Titan probe; orbiters - Galileo; and planetary flyby probes - Voyagers 1 and 2).
In general, all space robots have the same components that include a power supply, controller, actuators, sensors and radio communication unit. These sensors collect information about the robot and its environment, the controller processes the information and control instructions, and transmits the command signals to the actuators. The actuators in turn convert the signals and execute the operation.
Autonomous robots are operated independently as the long transmission ranges of radio waves prevent the remote control of such robots in real-time. Rovers that encounter craters, cliffs, rocks and other dangers are operated based on this concept.
Types of Space Robots
Remotely operated vehicles (ROV) and remote manipulator system (RMS) are the two major types of space robots.
A typical ROV can be a rover moving over the terrain upon landing, a lander operated from a stationary point and is in contact with an extra-terrestrial plain or an unmanned spacecraft. Besides being used by space researchers for terrain exploration in space, ROVs are used by bomb squads to detect potentially hazardous materials, in nuclear facilities and subsea.
RMS is the most common robotic device used in industry and manufacturing. It is more like a robotic arm that recreates various movements of the human arm including up-and-down, side-to-side and 360 degree circular motion. It can be either computer-operated or manually controlled.
So far, RMS has performed various functions on NASA space missions, by acting as a positioning and anchoring device, remote assembly device and grappler.
History of Unmanned Space Robots
Robotic spacecrafts are mainly used for space exploration activities taking place where the distance and hostility deems the mission too unsafe to send humans. From 1966 to 1968, a series of Surveyor spacecraft were sent to the Moon.
The surveyors triggered by remote control signals sent a number of images back to Earth and analyzed solid samples collected using an extendible claw. The US then planned its manned Apollo Moon missions based on this information.
The first mobile robot to investigate an extra-terrestrial region was the Soviet Lunokhod 1 lunar rover. This rover landed in the surface of Moon in 1970, and it was remote-controlled by the Soviet Technologists. One of the important functions of this robot was its ability to autonomously detect an event of turn over and stop and wait until it received signal from the Scientists.
Another interesting and practical application of ROVs is the unmanned deep space probes. For instance, the Voyager 2 is programmed to automatically adjust its operations without requiring any direct human interaction. Launched in 1977, the Voyager 2 has proved itself as one of the greatest unmanned space missions by enabling the Scientists to view Neptune, Uranus, Saturn and Jupiter, the planets that humans are unable to collect information from.
Recent Unmanned Space Missions
One cutting edge use of unmanned space robotics is NASA’s Dawn spacecraft, launched in 2007 to investigate the giant protoplanet Vesta and the dwarf planet Ceres. It is the first mission to orbit an object in the asteroid belt between Mars and Jupiter, and the only spacecraft ever to orbit two destinations beyond earth. Dawn orbited Vesta in 2011-12 and is currently orbiting and investigating Ceres.
Dawn is the first spacecraft to use ion propulsion, an extremely efficient propulsion system which uses an electrical charge to accelerate ions from xenon fuel to speeds of 7-10 times conventional chemical engines. The ion propulsion system will provide around 2,000 days of thrust over the course of the mission.
Another ground-breaking use of space robotics is the Rosetta spacecraft, a 10 year mission launched in 2004 to intercept a comet and land a probe on. The mission would take Rosetta into deep space, over five times the Earth’s distance from the Sun. This mission achieved many historic firsts, such as being the first spacecraft to orbit a comet’s nucleus and take images and the first touchdown on a comet.
Upon reaching the comet, the Philae lander unexpectedly bounced twice before landing and came to a stop in the shadow of a cliff, losing solar power. Rosetta made a final planned plunge into the comet as it headed out of the solar system, the mission providing pioneering information on the composition of comets.
Manned Space Robots
A manned spacecraft carries Astronauts to space. Unlike an unmanned probe, the manned spacecraft consists of a crew compartment and life support systems.
This type of spacecraft can either be reused as in the case of Space Shuttle or designed for one-time use as in Soyuz.
The latter model includes a re-entry module for accommodating the crew and a service module that includes life support systems, power supply and propulsion system. After the completion of the space mission, the re-entry module returns to Earth alone.
The first manned spaceflight was launched by the Soviet Union in 1961 as a part of the Vostok program. At present, only China and Russia maintain manned spaceflights. The first private human spaceflight was launched in 2004, when SpaceShipOne conducted a suborbital flight. NASA has also designed a private spaceflight via Commercial orbital transportation services and Commercial crew development.
Wider Benefits of Space Robots
Many technologies developed for space robotics have proved vital in other industries:
- Based on the technology used in the fuel pumps of space shuttle, a miniaturized ventricular-assist pump has been successfully developed for implantation in heart failure patients.
- Properties of metal alloys such as shape memory alloy investigated for the space station program has been used for designing golf club inserts, helicopter blades, medical equipment, etc.
- Blanket insulation kits for use in automobiles including race cars have been created using the NASA space shuttle thermal protection system materials to insulate heat-generating regions of cars.
- With the help of cutting edge three-dimensional (3D) virtual reality technology used in the development of planetary explorer vehicles, it is possible to develop powerful tools that graphically represent complex devices in a 3D environment.
Space robots are the most effective tool in space exploration. The most famous robots in space include orbiters, rovers and landers. Robots are widely being used wherever there is a need for better use of tools and data collection in space. The future of deep space exploration, with transit times in the order of decades will surely be carried out by unmanned robots
Robonaut, a humanoid robot developed by NASA, is another example that helps Scientists to explore deep space and distant celestial objects.
Sources and Further Reading