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Interstellar space travel is unmanned or manned travel between stars. The concept of interstellar travel in starships is a staple in science fiction. Interstellar travel is tremendously more difficult than interplanetary travel. Intergalactic travel, the travel between different galaxies, is even more difficult.

Many scientific papers have been published about related concepts. Given sufficient travel time and engineering work, both unmanned and generational interstellar travel seem possible, though representing a very considerable technological and economic challenge unlikely to be met for some time, particularly for crewed probes. NASA has been engaging in research into these topics for several years, and has accumulated a number of theoretical approaches.

The main difficulty of interstellar travel is the vast distances that have to be covered and therefore the time it takes with most realistic propulsion methods - from decades to millennia. Hence an interstellar ship would be much more severely exposed to the hazards found in interplanetary travel, including hard vacuum, radiation, weightlessness, and micrometeoroids. The long travel times make it difficult to design manned missions, and make economic justification of any interstellar mission nearly impossible, since benefits that do not become available for decades or longer have a present value close to zero.

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Credit: United States Air Force

Gas metal arc welding (GMAW), sometimes referred to by its subtypes, metal inert gas (MIG) welding or metal active gas (MAG) welding, is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode and a shielding gas are fed through a welding gun.

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Christopher Columbus Kraft, Jr. (born February 28, 1924) is a retired NASA engineer and manager. After graduating from Virginia Polytechnic Institute and State University in 1944, Kraft was hired by the National Advisory Committee for Aeronautics (NACA), the predecessor organization to the National Aeronautics and Space Administration (NASA). He worked for over a decade in aeronautical research before being asked in 1958 to join the Space Task Group, a small team entrusted with the responsibility of putting America's first man in space. Assigned to the flight operations division, Kraft became NASA's first flight director. He was on duty during such historic missions as America's first spaceflight, first orbital flight, and first spacewalk.

At the beginning of the Apollo program, Kraft retired as a flight director in order to concentrate on management and mission planning. In 1972, he became director of the Manned Spacecraft Center (later Johnson Space Center), following in the footsteps of his mentor Robert Gilruth. He held the position until his retirement from NASA in 1982. During his retirement, Kraft has consulted for numerous companies including IBM and Rockwell International, and he published an autobiography entitled Flight: My Life in Mission Control.

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