30-12-2010, 04:45 PM
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Nanotechnology is regarded world-wide as one of the key technologies of the 21st Century which is defined basically as Nanotechnology is the engineering of functional systems at the molecular scale. This covers both current work and concepts that are more advanced .The term nanotechnology usually refers to broad collection of most disconnected fields .Nanotechnology, or, as it is sometimes called, molecular manufacturing , is a branch of engineering that deals with the design and manufacture of extremely small electronic circuits and mechanical devices built at the molecular level of matter. The nanoscale is one billionth
Nanotechnological products and processes hold an enormous economic potential for the markets of the future. The production of ever smaller, faster and more efficient products with acceptable price-to-performance ratio has become for many industrial branches an increasingly important success factor in the international competition. The technological competence in nanotechnology will be a compelling condition to compete successfully with better procedures and products on high technology markets in the future. Due to its interdisciplinary cross section character, nanotechnology will affect broad application fields
Within the ranges of chemistry/materials ,medicine life sciences ,electronics/information technology ,environmental and energy engineering in various ways.
In space technology a high potential for nanotechnological applications is postulated. The increasing commercialisation of manned and unmanned space travel as well as ever more ambitious missions for the scientific investigation of the solar system and far space, requires the development of more efficient, more economical and more resistant space technologies and systems in the future. Nanotechnology could contribute significantly to solutions and technological breakthroughs in this area
Various applications of nanotechnology in space technology appear to be feasible in a short to medium-term time horizon, which could lead to major improvements in the area of lightweight and strong space structures, improved systems and components of energy production and storage, data processing and transmission, sensor technology as well as life support systems. Appropriate research and development projects have already been performed on various applications of nanotechnology in space technology appear to be feasible in a short to medium-term time horizon, which could lead to major improvements in the area of lightweight and strong space structures, improved systems and components of energy production and storage, data processing and transmission, sensor technology as well as life support systems. Appropriate research and development projects have already been performed
History:
The first time the idea of nanotechnology was introduced was in 1959, when Richard Feynman, a physicist at Caltech, gave a talk called "There's Plenty of Room at the Bottom " and disclosed we can arrange the atoms the way we want; the very atoms, all the way down .Though he never explicitly mentioned "nanotechnology," Feynman suggested that itwill eventually be possible to precisely manipulate atoms and molecules.
Feynman, There's plenty of Room at the Bottom In 1979, Eric Drexler encountered Feynman's talk on atomic manipulation and "nano-factories." The Caltech physicist's ideas inspired Drexler to put these concepts into motion by expanding Feynman's vision of molecular manufacturing with contemporary developments in understanding protein function. Drexler spent the next ten years describing and analyzing these incredible devices, and responding to accusations of science fiction. As a result, though the term was yet to be coined, the field of nanotechnology was created Drexler is credited as being the first person to use the word nanotechnology to describe engineering on the billionth of a meter scale .Drexler presented that if atoms are viewed as small marbles, then molecules are a tight collection of these marbles that "snap" together, depending on their chemical properties. When snapped together in the right way, these molecules could represent normal-scaled tools such as motors and gears. Drexler suggested that these "atomic" tools and machines would operate just as their larger counterparts do. From these principles, he sensationally proclaimed in his book that nanotechnology, through the molecular manufacturing of "universal assemblers," would revolutionize everything from biological science to space travel. Thus, with both his 1981 publication and his 1986 book, Drexler presented nanotechnology as a scientific field that solely revolved around his own expanded vision of Feynman's molecular manufacturing.
Needs of nanotechnology:
Reliable and durable materials are used for the manufacture of space vehicles are crucial for successful exploration missions of long duration in harsh environment .Future crew exploration vehicles ,habitats ,microcrafts , space suits,and other space systems will be constructed using high performance ,smart materials nano materials will be developed that are capable of serving several functions,including tolerating high mechanical stress/strains ,monitoring vehicle conditions as well as storing and delivering electric power.
Also ,high performance materials will be crucial because space resource are ,in particular ,there will be limited need for light weight and low density materials for future space and aeronautics system such as ultra large apertures and solar sails’ and there will be a need for materials with high strength per mass for launch vehicles and human space habitats.
At the nano scale many properties of matter are different from the properties at macro scale .As an example gold nano particles posses entirely different chemical, physical, electrical , magnetic ,and collective properties than bulk gold. The understanding and control of such unique properties enables nanofabrication.
Micro technology implemented devices are large in size but nanotechnology implemented devices enables them to be compressed to such an extent that they behave efficiently and accurately.
Construction:
Definitions aside, there are two different schools or approaches for “creating” nanotechnology material. These are the “top down” and the “bottom up” approaches. The top down approach involves reducing the structure sizes of microscopic objects to the nanometer scale using machining or etching techniques, the motivation for which is determined by microelectronics where sub-micrometer processes are being developed to move toward nanoelectronics for the next generation of electrical components. The bottom-up approach uses the controlled assembly of atomic and molecular elements to create larger systems. The bottom-up method has led to the development of several self-assembly.
Applcation nanotechnology in space:
Nanotechnology finds different application in space. Nanotubes are used for various application such as satellite protection. Satellites in space will be in harsh environment also subjected directed energy weapons. Nanotubes are used to provide efficient protections to satellites.
Nanotechnology based nanotubes are used in astronaut suits which give protection from HZE particles and radiation.
Nanotechnology is used to improve solar pannels of satellites. Using nanotechnology we can have solar cells for efficient utilisation of solar energy.
Carbon nanotubes are also used in improvement of batteries used in satellites. Electric rocket thrusters that uses a nanoparticle electric propulsion system enables space craft to travel faster with lesser propellant consumption.
Carbon tube nano wires can be used to reduce the sizes and weight satellite because the copper wirings form one fifth of overall weight of satellite Using nanotechnology we can have better sensors , computing system and instrumentation. Nanostructured heat insulating layers for rocket engines by means of Pulsed Laser Deposition.
IMPLEMENTATION:
Carbon-base materials are ideal as molecular building blocks for nanoscale systems because carbon exists in a variety of forms and provides the basic shapes needed to build complex molecular-scale architectures (i.e., planar sheet, rolled-up tubular, helical spring, rectangular hollow box, conical, etc.). One of the structures most commonly identified with nanotechnology is the carbon nanotube. First discovered in 1991, carbon nanotubes have spawned science and engineering research devoted entirely to carbon nanostructures and their applications due in large part to the combination of their structural perfection, small size, high stiffness, high strength, and excellent electronic properties. Carbon nanotubes are tubular structures of carbon, in which each carbon atom is positioned in a lattice that wraps into a hollow pipe with a diameter from a few to tens of nanometers and can be either single-wall or multi-wall. Single-wall carbon nanotubes are
best described as a rolled-up tubular graphene sheet composed of benzene-type hexagonal rings of carbon atoms. Multi-wall carbon nanotubes are multiple concentric single-wall carbon nanotubes. These two structures offer several interesting properties. First, single-wall carbon nanotubes can be either metallic or semi-conducting, depending on the chiral vector, or amount of twist, of the lattice structure.35 A carbon nanotube is metallic if electrons can freely move to the conduction band. A semi-conducting carbon nanotube requires additional energy before electrons can move to the conduction band. This has made them a candidate material for potential applications such as nanoscale devices and quantum wires. Researchers have demonstrated working carbon nanotube transistors which are a hundred times smaller than the 130-nanometer transistor gates currently found in computer chips and collections of nanotube transistors working together as simple logic gates.36
Carbon nanotubes conduct electricity better than metals because electrons traveling through carbon nanotubes follow quantum mechanical rules. Electrons exhibit ballistic transport, essentially behaving like a wave traveling through a smooth channel with no atoms to interfere
with their motion. Ballistic electron transport, supported by many studies, is considered one of the reasons that nanotubes exhibit high current density when compared with other materials at similar nanoscale. This has resulted in considerable enthusiasm over the possibility of using carbon instead of silicon in the field of nanoelectronics. Multi-wall carbon nanotubes can pass a very high current density, from 106 to 108 amperes/cm2, without suffering adverse effects. However, long-term stability while operating at these current densities remains a question. As conventional CMOS electronics will soon reach economical and physical limits, nanoelectronic technologies may provide the basis for continued scaling of electronics into the next decade, following Moore’s Law, and may provide the potential for hybrid architectures combined with traditional electronics.40
Nanotechnology could make a major contribution to human space flight as radiation shield. The risks of exposure to space radiation are the most significant factor limiting humans’ ability to participate in long-duration space missions. A lot of research therefore focuses on developing countermeasures to protect astronauts from those risks. To meet the needs for radiation protection as well as other requirements such as low weight and structural stability, spacecraft designers are looking for materials that help them develop multifunctional spacecraft hulls. Advanced nonmaterial’s such as the newly developed, isotopically enriched boron nanotubes could pave the path to future spacecraft with nanosensor-integrated hulls that provide effective radiation shielding as well as energy storage. Space radiation is qualitatively different from the radiation humans encounter on Earth. Once astronauts leave the Earth's protective magnetic field and atmosphere, they become exposed to ionizing radiation in the form of charged atomic particles traveling at close to the speed of light. Highly charged, high-energy particles known as HZE particles pose the greatest risk to humans in space. A long-term exposure to this radiation can lead to DNA damage and cancer. One of the shielding materials under study is boron 10. Scientists have known about the ability of boron 10 to capture neutrons since the 1930s and use it as a radiation shield in geiger counters as well as a shielding layer in nuclear reactors.
