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NASA ending stocks of plutonium-238
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High Flux Isotope Reactor at Oak Ridge National Laboratory for NASA produces a small amount of plutonium-238, enriching neptunium-237 i>
Sluggish production of nuclear fuel threatens NASA plans to launch a spacecraft nuclear engines. If the problem can not solve, it is necessary to restrict solar energy.
The ideal fuel for nuclear engine is plutonium-238 (Pu-238). Four kilograms of fuel is enough to ensure that the ship energy for decades. NASA in its history, has spent 140 kilograms of plutonium, including experiments in the framework of the "Apollo" on a mission "Galileo" to Jupiter to send a series of devices "Pioneer" and "Voyager". Right now plutonium gives heat and electricity rover Curiosity, orbital station "Cassini" Saturn, the spacecraft "New Horizons", flown away to the Kuiper Belt.
The plutonium would be very useful for robotic probes that can dive to the depths of the ice moons in the solar system, where there is underground ocean of water. For aircraft that will fly in the atmospheres of other planets and explore new territory. For ships that travel the lakes and rivers of liquid methane and ethane on Titan's surface. For a variety of other missions. But plutonium is over and there is a suspicion that by nuclear engines will have to give up if you do not take resolute political decision.
In the US the production of the isotope plutonium-238 was stopped in 1988. US Department of Energy signed in 1992 a five-year contract to purchase the isotope from Russia in the amount of 10 kg and the possibility of increasing the supply of no more than 40 kg. The contract consisted of several contracts, the agreement was extended. In 2009, deliveries were interrupted due to the restructuring of the Russian nuclear industry, and now NASA was in a quandary, пишет the magazine Scientific American.
Attempts to establish the Department of Energy enrichment of Pu-238 in the Oak Ridge National Laboratory does not give an acceptable result: production of isotopes of neptunium-237 is too low.
Now NASA has left stocks of 35 kilograms of Pu-238, and radioactive decay of 35 to 18 kg is too weak to be used in existing thermoelectric generators NASA. According to experts, 17 kg of propellant enough only four generators, one of which is already reserved for the rover in the mission "Mars 2020».
In 2013, after twenty-five break US Department of Energy has resumed production of plutonium-238 in the Oak Ridge National Laboratory, but the project ran into technical difficulties and is already behind schedule, so it is unlikely to reach the planned capacity of 1, 5 kg of plutonium per year by 2021. Instead, the engineers say about the production of 0, 5 kg per year by 2019.
Repeatedly raised the issue in Congress, trying to extract information from NASA about the current situation, the number of necessary plutonium and possible ways to get it, but the National Space Agency silent. There was also an attempt to pass a law Efficient Space Exploration Act for the planning of material support of NASA, but he too is stuck in parliamentary committees.
In other words, now at NASA's no plan and a clear understanding of what to do next, says Scientific American. Independent experts have criticized the position of NASA, which states there is no need for additional stockpiles of plutonium. Mol, and the current stock is sufficient for the planned missions. But this is a classic example of the vicious circle. Current reserves enough because few planned missions. Few missions planned, because not enough plutonium. If fuel was more, it certainly would have found much use.
For example, for several decades, scientists have dreamed of going to Europe, the probe, the satellites of Jupiter, where under the ice could theoretically support life. But these plans are constantly delayed due to the large amount of plutonium required. For the last project Jupiter Europa Orbiter demanded 17, 6 kg of Pu-238, which is more than has left NASA.
The problem is compounded by the fact that in 2013, Congress and the White House shifted to NASA's costs of restarting the production line for the job of plutonium and research laboratories. Now, these costs amount to $ 50 million a year. As costs fell on the shoulders of NASA, then had to cut funding for certain scientific and technical programs, including programs for the development of new types of generators that can reduce the consumption of plutonium. Again a vicious circle.
Engineers are trying to solve the problem differently. For example, there is an idea to launch a probe to Europe not plutonium, and the orbiter on solar energy, which will perform a number of ingenious maneuvers, approaching the surface at close range.
In some respects, the solar panel even outperform thermoelectric generators: they weigh less, are deployed on the desired capacity, depending on the needs of the unit. So, for a mission to Europe will need solar panels of 50 m 2 sup>. Batteries of this type will be tested on the machine Juno, who will arrive to Jupiter in July 2016.
Faced with a shortage of plutonium, the engineers have to rely on solar energy and improved technology: increase the efficiency of solar cells by using concentrators and mirrors, panels, new designs.
But no matter how hard the engineers, there are missions that are essentially impossible to provide solar energy. Anyway, if you think the same lander "Philae" is continuing to work on the comet 67P / Churyumov-Gerasimenko, if it stood on the nuclear engine, rather than solar panels. In general, it is necessary, or to negotiate with Russia, or to take a political decision on the resumption of its nuclear program, which stopped with the end of the Cold War.
Source: geektimes.ru/post/262544/
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