Technology from the 60s of the last century, supporting NASA’s Voyager Probes for nearly 50 years

Feeding a spacecraft with solar energy may not seem like a challenge, given how intense the light of the sun can feel on Earth. Spacecraft near the ground Use large solar panels to harness the sun for the electricity needed to manage their communication systems and scientific instruments.

However, the further in space, the greater the sunlight becomes and the less useful it is for supply systems with solar panels. Even in the internal solar system, spacecraft such as Lunar or Mars Rovers need alternative energy sources.

As Astrophysicist and Professor of PhysicsI teach a high -level aerospace engineering course in the space environment. One of the key lessons I emphasize to my students is how much space can be. In this extreme environment where the spacecraft has to withstand intense solar flames, radiation and temperature changes from hundreds of degrees below zero to hundreds of degrees above zero, engineers have developed innovative solutions to feed some of the most remote and isolated space missions.

So, how do engineers feed the missions in the external achievements of our solar system and outside? The solution is the technology developed in the 1960s, based on scientific principles discovered two centuries ago: Radioisotope thermoelectric generatorsor RTGS.

RTGS are essentially batteries with nuclear energy. But unlike AAA batteries in your television remote, RTG can provide power for decades, while hundreds of millions of billions of miles from the ground.

Nuclear

Radioisotope thermoelectric generators do not rely on chemical reactions Like the batteries in your phoneS Instead, they rely on the radioactive decay of elements to produce heat and possibly electricity. While this concept sounds similar to that of a Nuclear power plantRTG work on a different principle.

Most RTGs are built using the Plutonium-238 As their source of energy, which cannot be used for nuclear power plants as it does not support division reactions. Instead, plutonium-238 is an unstable element that will undergo a radioactive decay.

Radioactive breakdownOr nuclear decay, occurs when the unstable atomic nucleus spontaneously and randomly radiates particles and energy to reach a more stable configuration. This process often causes the element to change to another element as the nucleus may lose protons.

When the plutonium-238 breaks up it radiates alpha particleswhich consist of two protons and two neutrons. When Plutonium-238, which starts with 94 proton, releases the alpha particle, it loses two protons and becomes Uranus-234, which has 92 protons.

These alpha particles interact and transfer energy to the material surrounding the plutonium that heats this material. The radioactive decay of plutonium-238 releases enough energy that it can shine red from its own heat, and it is this powerful heat that is the source of energy to supply RTG.

Heat as power

Radioisotope thermoelectric generators can turn heat into electricity using a principle called the Seebeck effect discovered by German scientist Thomas Zebek in 1821S As an additional benefit, the heat of Some types of RTGS It can help maintain electronics and other mission components in a deep space warm and work well.

In its main form, the effect of Seebeck describes how two wires with different conductive materials, connected in the outline, produce current in this cycle when exposed to a temperature difference.

Called devices that use this principle thermoelectric pairs or thermocouchesS These thermocodes allow RTG to produce electricity from the difference in temperature created by the heat of the decay of the plutonium-238 and the frigid cold of the space.

Radioisotope Thermoelectric Generator Design

In a basic thermoelectric generator of radioisotope, you have a container of plutonium-238, stored in the form of plutonium-dixide, often in a solid ceramic state, which provides additional safety in the case of an accident. The plutonium material is surrounded by a protective layer of Foil insulation to which is attached a large array of thermocouches. The whole assembly is inside the protective aluminum body.

The interior of RTG and one side of the thermocouches is kept hot – near 1000 degrees Fahrenheit (538 degrees Celsius) – while the outside of RTG and the other side of the thermocouple is exposed to space. This from the outside, a layer aimed at space can be as cold as several hundred degrees on Fahrenheit below zeroS

This strong temperature difference allows RTG to turn heat from radioactive decay into electricity. That electricity feeds any spacecraft, from communication systems to scientific instruments to rovers on Mars, Including five current NASA missionsS

But don’t worry too much about buying RTG for your house. With this technology they can only produce a Several hundred watts of powerS This may be enough to power a standard laptop but Not enough to play video games With a powerful graphic processor.

However, for missions in deep space, these few hundred watts are more than sufficient.

The real benefit of RTGS is their ability to provide predictable, constant power. The radioactive decay of plutonium is constant – every second of every day for decades. For about 90 years, Only half the plutonium I will break up in RTG. RTG does not require moving parts to generate electricity, which makes them much less likely to break up or stop working.

They also have An excellent safety recordAnd they are intended to survive in their normal use and also be safe in the event of an accident.

RTGS in action

RTGS are key to the success of many NASA solar system and deep space missions. Thehe Mars Curiosity and Persistence Rovers and New Horizons spacecraft This was visited by Pluto in 2015. RTG used. New Horizons travels from the solar system, where RTGS will provide power where solar panels cannot.

However, no missions capture the power of RTG, such as Voyager missions. NASA launched Twin Spacecraft Voyager 1 and Voyager 2 in 1977 to take a Circumference of the external solar system And then a trip beyond it.

Each craft was Equipped with three RTGProviding a total of 470 watts of launching. Almost 50 years have elapsed since the Voyager probes launch and the two are still active scientific missions, Collecting and sending data back to the groundS

Voyager 1 and Voyager 2 are about 15.5 billion miles and 13 billion miles (nearly 25 billion kilometers and 21 billion kilometers) respectively from Earth that makes them the farthest objects created by manS Even at these extreme distances, their RTG still gives them constant power.

These spacecraft are a testament to the invention of the engineers who for the first time designed RTG in the early 1960s.

Benjamin RulstonPhysics Assistant, Clarkson UniversityS This article has been reissued by Conversation Under Creative Commons license. Read Original articleS