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The shortage of inventory of plutonium-238 jeopardizes space exploration
Fiction | The shortage of inventory of plutonium-238 jeopardizes space exploration
In 1977, the spacecraft “Voyager 1” left the Earth for five-year mission to study Jupiter and Saturn. Thirty-six years later, probe the size of a car is still exploring space, sending data back home. Between him and the Sun – 19 billion kilometers. Last week, NASA announced that the “Voyager 1” became the world’s first starship .
The distance to this star was “car” unimaginable. It is so far that the signal from the probe reaches the Earth for 17 hours. On the way, “Voyager 1” is sent to scientists first intimate images of Saturn, the first images of the rings of Jupiter, has opened many moons circling around these planets, and also found that Jupiter’s moon Io is full of active volcanoes. Now the spacecraft exploring the solar system boundary, passing through the remains of the heliosphere, where the Sun’s influence is still felt, and the heliopause, where the cosmic currents are struggling with the solar wind.
It is assumed that the “Voyager 1” will last until 2025, then the battery will sit down and finish shot in the locker.
Hardly anything of the above would have been possible without the three batteries spaceship filled with plutonium-238. A large part of what mankind knows about the outer planets, it was revealed by the power of plutonium. The current study Saturn probe “Cassini” journey “Galileo” to Jupiter, the work of “Kyuriositi” on the surface of Mars and Pluto fly-unit New Horizon in 2015 will also be plutonium. Features of the radioactive decay of the metal make it sverhtoplivom. More importantly, there is no viable alternative. Solar energy is too weak, short-lived chemical battery systems, nuclear fission is too heavy.
We are highly dependent on plutonium-238 – fuel, which is largely produced as a by-product of the manufacture of nuclear weapons. But there is a problem.
Reserves are almost exhausted.
“We have enough to make it to the end of this decade. That’s it, “- said Steve Johnson, a nuclear chemist from the Idaho National Laboratory. And it’s not just American reserves. Stocks ran almost the entire planet.
This makes plutonium-238
Scientific reserves the U.S. at the moment is about 16 pounds. To understand the perspective, consider: battery, which powers the rover “Kyuriositi” currently exploring the surface of Mars contains about 5 kg of plutonium. And what is left, is also distributed. The consequences for the space program terrifying: we need to explore the solar system, 99%, and plutonium-238 is not. Why then spend half a billion dollars a year in the study of the planets? More precisely, the study of the planets, if there is no one to learn? The nuclear crisis is so bad that the researchers call it a “problem.”
It should not be. The raw materials, reactors and infrastructure for the production of plutonium-238 (which, unlike plutonium-239 can not be used to make a nuclear bomb) – you’re done. Moreover, the U.S. government has recently approved spending $ 10 million a year to restore production, collapsed almost 20 years ago. In March, the Ministry of Energy has made even a small amount of fresh plutonium for a nuclear reactor in Tennessee.
A great start, but the crisis is far from resolved. Political ignorance and shortsightedness States, along with the false promises of Russia, as well as small-minded management, which is famous for NASA, all this prevents the production of plutonium-238. The result? Exploration of the solar system is on the brink of the abyss. One ambitious space flight can drain the remaining stockpiles of plutonium, and any deviations in the supply chain of the future can rip any of the upcoming missions.
The only natural source of plutonium-238 has dried up even before the Earth was finally formed, about 4.6 billion years ago. Silver metal produced exploding stars, but during his life, or the time required for 50 percent disappearance of the material is less than 88 years old.
Fortunately, we figured out how to make it yourself and use to create a highly reliable source of energy. Like other radioactive materials, plutonium-238 decays because its atomic structure is unstable. When the nucleus decays spontaneously, it fires a helium core at high speed, leaving a uranium atom. These bullets helium called alpha radiation, bulk face nearest piece atoms within plutonium – material which is twice as thick lead. This energy can heat the plutonium pucks to 1260 degrees Celsius. To convert this energy into useful power, you wrap it in the washer thermoelectrics, which convert heat into electricity.
Voila. We have a battery that can power spacecraft for decades.
“It’s a magic isotope. Just perfect, “- said Jim Adams, NASA Deputy Chief Technologist and former deputy director of planetary science.
In the U.S., production is carried out in two nuclear labs that produce plutonium-238 as a by-product from the production of “a more useful state” of plutonium-239. Hanford Site in Washington State throws plutonium-238, along with a cocktail of nuclear waste. Savannah River Site in South Carolina, it is worth noting learned and processed more than 180 pounds during the Cold War to provide food spy satellites and dozens of small space ship NASA.
By 1988, when the Iron Curtain began to shine holes, the United States and the Soviet Union began to dismantle the military nuclear facilities. Hanford and Savannah River stopped producing plutonium-238. But Russia has continued to produce material by processing nuclear fuel at the nuclear industrial complex “Mayak”. Russia sold the first batch of plutonium, weighing in at 18 pounds, U.S. in 1993 at the price of more than 1.5 million dollars per kilogram. Russia has become the sole supplier of the planet, but soon stopped taking orders. In 2009, she refused to sell 11 kilograms of the United States.
Whether there was anything in Russia and whether it can do more – is unknown.
“What we know for sure is that they do not want to sell more plutonium,” – said Alan Newhouse, a former consultant on nuclear power, which was headed by the first purchase of the stock of plutonium-238 from Russia. – “I have heard that they have nothing else to sell.”
By 2005, according to the report of the Ministry of Energy, the U.S. government has 40 kilograms, of which two-thirds were for projects of national security is likely to deep-espionage equipment. Wired reports that the Department of Energy did not disclose how much fuel is left today, but scientists say that NASA is left only 18 pounds.
That’s enough, the space agency has launched several small space missions until 2020. The twin rovers’ Kyuriositi “should go to Mars in 2020, and it will require a third of stocks. After that interstellar research program NASA will be left with nothing – especially the most voracious, like “Orbiter”, which was supposed to fly to Europe. To look for signs of life on the icy moons of Jupiter, the spacecraft will need more than 25 kilograms of plutonium.
Advanced Test Reactor
“The situation with supplies already affecting the planning of missions”, – said Alice Caponiti, a nuclear engineer from the Department of Energy, whose tasks is restart production of plutonium-238. – “If you are planning a mission that will take eight years, the first thing you need to find – it’s fuel.”
Many of the eight deep space missions that NASA wants to implement in the next 15 years has already been canceled or delayed. Other missions – some of which have not yet offered – do not even open his mouth, looking at poverty in terms of NASA-grade plutonium. Since 1994, scientists have pleaded with the powers to restart production. The Department of Energy believes that even a modest 10-20 million annual funding for 2020 will be able to give us a half to five pounds of plutonium-238 in a year. It’s enough to make the spacecraft could safely “breathe.”
In 2012, a single line in the 17-billion NASA budget was 10 million on an experiment to create a small amount of plutonium-238. Objectives: To estimate how much can be done at all, to assess the cost of a full-scale production, to prove that the U.S. could start production again. It was half the money requested by NASA and the Department of Energy (law prohibits NASA to produce plutonium-238). The experiment may last for seven years and do about 85-125 million.
At Oak Ridge National Laboratory in Tennessee nuclear reactor, the researchers used a High Flux Isotope, to make a few micrograms of plutonium-238. Completely revamped program for the production of plutonium has been described in terms of the Department of Energy, released last week, and it will also involve a second reactor west of Idaho Falls, called Advanced Test Reactor.
This facility is located at the ranch Idaho National Laboratory. Sun roasts well this desert area. Armed guards stopped and checked vehicles at roadside outpost. Everything is closed with barbed wire and electrified fences.
Over the last checkpoint security hidden room the size of a small warehouse with a concrete floor. Paul striated yellow lines that secrete a small pool, covered by a metal lid. For her – 18 meters of water, which absorbs radiation. Halfway to the bottom of the reactor core is stored in a two-meter four-leaf clover shape dictated by the wedge-shaped pencils uranium.
“That’s where it hides neptunium,” – says a nuclear chemist Steve Johnson, pointing to a diagram of the radioactive clover.
Neptunium, plutonium direct neighbor in the periodic table and stable by-product of the era of the cold war, nuclear reactors, is the material from which it is easiest to make plutonium-238. In the place where indicated Johnson, engineers take rolls of neptunium-237 and drop them into the reactor core. Neptunium-237 atom absorbs a neutron emitted by decaying uranium nucleus, loses an electron and becomes plutonium-238. After a year or two – after disappear harmful isotopes – machinery rolls bathed in acid to remove the plutonium and neptunium are sent to new revisions.
The inevitability of decay and the limited space of the reactor means that you may need five to seven years to make half a kilogram clean and ready to use plutonium. Even if it is running full production, NASA will squeeze every last watt from the fact that there will always be a fairly small margin.
Standard power supply, which is called multi-purpose thermoelectric generator – the one that feeds “Kyuriositi” – will not take it into account for future research.
“They are reliable, but use a hell of a lot of plutonium,” – says Johnson.
In other words, NASA does not just need a new plutonium. The agency needs a new battery.
In the confusion of the basement NASA Glenn Research Center in Cleveland hidden metal cage and a clear plastic box with a buzzing devices. Many of them look like stainless steel rod about a meter long, entangled in wires, while others resemble the white boxes the size of two small tables.
This “zoo” of machines consists of a prototype next-generation nuclear energy systems NASA called “advanced Stirling radioisotope generator» (Advanced Stirling Radioisotope Generator). It promises to be an extremely efficient nuclear battery, surpassing any before it.
Outside the vehicle stationary. Inside is a barrage of traffic Stirling cycle, developed in 1816 by the Scottish clergyman Robert Stirling. Gasoline engines burn fuel for the rapid expansion of air that pushes the pistons, but the Stirling converters only thermal gradient. The greater the difference between the hot and cold parts of the Stirling engine, the faster the pistons. When the heat warms one end sealed chamber containing helium gas expands, pushing the piston magnet loaded the pipe with wire helix to generate electricity. The cold gas is returned to the hot side, sucking the piston back again to restart the cycle.
“Nothing with nothing touching. That’s the beauty converter “- said Lee Mason, one of several engineers, NASA, gathered in the basement. Their pistons swim like an air hockey puck in, only helium.
For every 100 watts of heat generated, Stirling generator converts more than 30 watts in electricity. This is almost five times better than that of a nuclear battery, power supply, “Kyuriositi.” The generator may use one-fourth of plutonium, while electric power will increase at least 25%. Less plutonium – so these motors will weigh two-thirds less than a 50-pound pack “Kyuriositi.” An important difference to the spacecraft, which will go a long distance. “Kyuriositi” was the big heavy machine NASA, which the agency sent to Mars, and the vast majority of the mass of it was devoted to a safe landing, not a science. Reducing weight increases the ability to add interesting tools in future flights.
However, the technology is relatively complex Stirling generator that bothers people who design flying in deep space.
“People are worried about the fact that this device has no moving parts,” – said John Hamley, Program Manager of Nuclear batteries NASA. The movement can interfere with the spacecraft instruments that need to be sensitive enough to map the gravity, electromagnetism, and other subtle phenomena in space.
As a solution to the problem, each generator uses a Stirling two transducers facing each other. On-board computer continuously synchronizes their movements to compensate mutually interfering vibration. To detect and correct design flaws, engineers have pushed their generators in vacuum chambers, put on the shaking table and threw powerful bursts of radiation and magnetism.
The first prototype of the advanced Stirling radioisotope generator
Usually NASA tests new technologies and a half times longer than necessary before running them into space. Stirling generator will need 25 years. The tests began in 2001, reducing the delay of up to 13 years – but it’s more than NASA can not wait. In 2008, only one of the 10 nuclear missions involved devices. By 2010, seven of the eight missions planned until 2027, it took generators.
To expedite the process, Hamley and his team are working with ten different units simultaneously. The oldest unit runs almost continuously for 10 years, and the new design was launched in 2009. The total number of data generators Stirling recorded for 50 years, which is sufficient to model the fast-forward and active testing. Hamley says that everything is stable. Currently, his team is building two poletosposobnyh generator, the third will be tested on the ground.
But for all the promise of technology, it is “not solve the problem,” says John. Even with the use of the Stirling generator of plutonium-238 will only last until 2022.
Any delays in the financing program for the production of plutonium-238 will deliver the planetary science to a standstill or strangle built on nuclear fuel mission. The views of scientists and optimistic at the same time, and sad.
Why? It took a lot of scientists and lobbyists to 15 years to attract at least some attention to the board. Sad to report on the “problem” of 2009 was signed by more than five dozen scientists, which ultimately helped to clear at least some funding from the national budget in 2009. Congress took three years to see whether it is possible to allocate this $ 20 million of taxpayers’ money.
“Not a day goes by when I do not think of plutonium-238”, – said Jim Adams, a former deputy chief of planetary science NASA.
At the National Air and Space Museum in Washington, Adams looks through the glass at a nuclear miracle, which took place the conquest of space in his youth. On the fake moon dust is the model of SNAP-27, the battery on plutonium-238, which was equipped with a device, exploring the moon after the “Apollo 11” .
A few steps away from the booth is the first model of “Viking”, which landed on Mars in 1976 and began to dig a planet in search of water and life. He found nothing. “We dug deep enough” – said Adams. – “A total of 4 inches below the depth to which came the” Viking “, there was a layer of ice untouched.”
One floor above the hanging model of the “Voyager”, suspended from the ceiling.Three nuclear power source on board the actual spacecraft were what allowed the “Voyager 1” and its twin “Voyager 2” to stay in touch with the Earth 36 years later. Any other type of food has dried up to a decade ago.
The same technology powers the device “Cassini”, which continues to explore Saturn, sending valuable data stream and amazing pictures of the planet and its many moons. Future circled Pluto as “the new horizons” hardly have been possible without such a reliable source of supply.
“Viking” had to dig a little deeper. Now it needs to be done to us.
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Tags: NASA , The Universe , Space flight , nuclear fuel .
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