Launchpad: What Are Radioisotope Power Systems?


Hi there and welcome to NASA launchpad, I'm, your host Molly. We use electricity every day it's in our homes it's in our schools it's, even in our cars. So let's think of some ways of generating electrical power. Well to start there's solar power, which makes energy from sunlight.

There's also wind power, which uses the force of winds to turn a turbine and make electricity there's, hydroelectric power or water power, which uses the force of flowing water to do the same thing and then there's something. Called radio isotope power, not familiar with that. Last one don't feel bad most people aren't, and it's because it's, not something we use in our everyday lives. Radioisotope power systems are a special type of technology that NASA uses to provide energy to run some of its space missions that explore the solar system. Okay.

So it's, an electrical power system. You get that, and it's a type of nuclear power, but probably not what you're thinking there's, no nuclear fission control rods or cooling towers. Involved so how does it work? A radioisotope is a variation on an atom.

We have basic atoms like carbon, and it has a atomic number of sixes. And that means there are six protons in the center of it. But it also has neutrons, and you're going to have a different number of neutrons.

So carbon-12 has six protons and six neutrons. But carbon 13 has six and seven neutrons plutonium-238, which is the isotope we're interested in is an unstable atom. If you have an atom that's, not at a stable energy state, it wants.

To give off that energy and become a new element and that's. What happens with plutonium, 238 in our case, the whole process is actually pretty simple as the radioisotope plutonium-238 hair. It produces heat, and that heat can be put to work to produce electricity. So a radioisotope power system is basically a device that uses heat to produce electricity and NASA uses these for space missions. The great thing about radioisotope power systems is that they produce electrical power continuously in a. Predictable way for a long time, they produce this power, whether it's sunny or dark really hot or freezing, or whether the spacecraft's in a place that's dusty or filled with radiation from charged particles like the space around the planet Jupiter.

So that means the use of radioisotope power enables long missions to some of the most extreme environments. We can imagine. So as we said, the heat from radioactive decay is converted into electricity. But how exactly does that work? Thermocouples are very. Interesting because their devices that you find all over your house, everything from your ovens to your hot-water heaters, if you apply heat on one side of a thermoelectric and coal to the other side, you can get electricity out in four space applications, mostly we use them to generate electricity to power our spacecraft.

We have radioisotope heat sources that provide the hot side for our thermocouples. And then we have deep space, providing the cold side. Okay, check this out thermocouples. Take.

Advantage of an electrical effect called the Seebeck effect. And that occurs at junctions between different metals, when they're exposed to a significant difference in temperature, for example, take one iron wire and one copper wire, twist one end of the copper wire and one end of the iron wires together with the other end of the copper wire and the other iron wire. Now, if you heat one of the twisted junctions and attach the wires to a voltmeter, you will be able to measure a voltage that means. Electricity is flowing and that's, basically how the radioisotope power systems, the ones used by NASA so far work, the heat from the decay of plutonium, 238 is like the flames energy given off by that match if it could burn steadily for years and years, of course, it's, not quite as simple as striking a match and heating some wires let's learn more about the engineering involved in this remarkable technology. What's really exciting about RPS technology is that you're able to get so much energy out of. Such a small package, well, the first technology you need, of course, is to make the plutonium, 238 and to refine it and get it into the form that you need. So there are a lot of nuclear technologies or a lot of chemical technologies that you needed to do that.

And then there's all the materials technologies, the electrical technologies. And all of that has to go together in a way that is stable. And that it's, compact, we're, literally, flying spacecraft that have been up in space longer than three decades. Using these same radioisotope power systems, and they're still sending data back to us.

So what's next for RPS, a SG or advanced throwing radio photo generator is the next generation of radios that took power systems that NASA's working on the big difference between an ASR G. And an RTG system is that it has moving parts. And in that generator, there is a Stirling engine. Well, the Stirling power system is actually four times more efficient than the materials type systems using thermoelectric it's, a.

Much more efficient system using a moving mass alternator than it is using the physics of the materials properties when you add heat on one and have a cold site on the other one of the things, the AS G allows us to do is first and foremost use a lot less of precious resources of plutonium-238. But secondly, it allows us to be more compact in the power system. Okay, a quick review radioisotope power systems. Last for a long time like decades, they're, rugged, compact, highly reliable and not easily. Affected by the environment where a mission has to operate they're, ideally suited for certain long-duration missions in the intense environments of space and on alien worlds in our own cosmic backyard.

Well, that's it for this time. Thanks for watching I'm, Molly and I'll catch you next time on NASA launchpad.

Dated : 06-Apr-2022

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