Chemistry in Improving Conditions for Space Travel
As technology advances and the urge to discover the Universe and search for other civilizations becomes more and more pertinent, researchers have been discovering ways to improve conditions for space travel so that astronauts are accessible to travel further in a smaller amount of time. Scientists think that Nuclear Rockets could be a reality to utilize for space exploration. NASA is investigating and researching many technologies for nuclear rocket propulsion and nuclear power for bases on the Moon and Mars. The nuclear rocket system will use electricity generated by a nuclear reactor to power an electric ion drive system. The new generation of space-craft will be capable of taking man to the outer reaches of the solar system that no one has explored before. The concept of nuclear rockets is, in fact, 50 years old. Between 1957 and 1972 several nuclear rocket designs were proposed, but only a few were partially tested. A major problem with the chemical rocket systems is weight. Chemical fuels are heavy and add much weight to the launch vehicle. In addition to electricity and thrust, the early designs exhibited a couple of design flaws that were never fully resolved by the program for Chemical Rockets’ end. They mostly rattled and vibrated enough to crack the fuel bundles, making the rockets useless. The rockets also became so hot that the heated hydrogen steam eroded the walls of the reactor.
In 1998, NASA launched Deep Space 1 and Deep Space 2, and they successfully demonstrated that an electrostatic ion engine could propel a spacecraft. Both spacecrafts were able to successfully follow comets and report back photographs. Deep Space 2 successfully reached Mars but the surface probes failed to function. In both cases, the electrostatic ion engines performed better than expected. The way the engine works is that it is bombarding a gas with a beam of electrons. This action knocks electrons off the atoms of the gas and creates a positively charged ion. There are high voltage metal grids at the back of the engine chamber which accelerate the positive ions toward the grid. As the ions pass the grid, they reach speeds of over 30 km/s and are focused into an ion beam before being exhausted out the back of the engine. Lastly, a neutralizer collects excess electrons and injects them into the ion beam to prevent a build-up of negative charge on the spacecraft, which could have a negative effect on the spacecraft and result in failure. Plutonium-238 is a valuable commodity for deep space exploration where insufficient amounts of sunlight render solar panels useless. NASA's radioisotope thermoelectric generators (RTG) that most of power these missions instead run on a nugget of Pu-238. While plutonium is a poor conductor of electricity, its emission of alpha particles as part of its decay process generates a terrific amount of heat to run the RTGs.
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