Technology in the sixties of the last century maintains NASA’s investigations alive for nearly 50 years

Solar spacecraft with solar energy vehicles may not seem like a challenge, given the popularity of sunlight on Earth. The spacecraft near Earth Use large solar panels to harness the sun for electricity to operate communication systems and science tools.

However, the more the space you go to, the weaker and the less useful for sunlight for solar panel operating systems. Even in the inner solar system, spacecraft such as the moon or Mars need alternative power sources.

as Astronomical physics and professor of physicsI teach a large level space engineering course around the space environment. One of the main lessons that I assure my students is the extent to which space is not connected. In this extremist environment where the spacecraft must withstand intense solar torches, radiation fluctuations and temperatures of hundreds of degrees that are less than zero to hundreds of degrees above zero, engineers have developed innovative solutions to operate some of the most distant and isolated space tasks.

So how can engineers have energy tasks in the external areas of our solar system and beyond? The solution is the technology that was developed in the 1960s based on the scientific principles that were discovered two centuries ago: Raditional thermal juvenile generatorsOr rtgs.

RTGS is mainly nuclear powered batteries. But unlike AAA batteries in a remote control control device, RTGS can save energy for decades while hundreds of millions to billions of miles from Earth.

Nuclear energy

Radical thermal hydroelectric generators do not rely on chemical reactions Like batteries in your phone. Instead, they depend on the radioactive decomposition of the elements to produce heat and electricity in the end. While this concept seems similar to the concept a Nuclear power plantRTGs works on a different principle.

Most of RTGS is designed with Plutonium 238 As an energy source, which cannot be used for nuclear power plants because it does not maintain fission reactions. Instead, Plutonium-238 is an unstable element that will be subject to radioactive decay.

Radiant decayOr nuclear decay, occurs when an atomic nucleus is automatically stable, randomly of particles and energy to reach a more stable composition. This process often changes the element to another element, because the nucleus can lose protons.

When Blloonium -238 decomposes, it is emitted Alpha particlesWhich consists of two proton and two neutrons. When Blloonium -238, which starts with 94 proton, is released, the alpha particle, it loses protons and turns into uranium -234, which contains 92 protons.

These alpha molecules interact and transfer them to the energy surrounding plutonium, which heats this substance. The radioactive dissolution of the plutonium -238 is adequate energy that can glow in red from its own heat, which is this strong heat is the power source for RTG.

Heat as energy

Radio thermal thermal generators can turn into electricity using a principle called the Sebeck effect, which was discovered by German scientist Thomas Speck in 1821. As an additional benefit, heat from Some types of RTGs It can help maintain electronics and other components of the warm deep space and work well.

In its primary form, the Sebeck effect describes how two of different connecting materials are produced in a stream in that episode when exposed to the temperature band.

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The devices that use this principle are called Thermal pairs, or thermal doubles. These thermal doubles allow RTGS to produce electricity from the difference in the temperature created by the temperature of plutonium -238 decomposition and cold cold from space.

PV generation design

In a basic photovoltaic generator, you have a plutonium -238 container, stored in the form of a bioxide plutonium, often in a solid ceramic condition that provides additional safety in the event of an accident. Plutonium is surrounded by a protective layer of Displacement isolation Which is attached to a large group of thermal doubles. The whole assembly is inside the protective aluminum cover.

The interior of the RTG and one side of the thermal double – is preserved on approximately 1000 degrees Fahrenheit (538 ° C) – while the outer part of the RTG and the other side of the thermal double are exposed to space. This outer layer that faces a cool space can be like a A few hundred degrees Fahrenheit is less than zero.

This strong temperature difference allows RTG to convert heat from radiation decomposition to electricity. Electricity works on all types of spacecraft, from communications systems to science tools to Rover on Mars, Including five NASA missions.

But do not feel very enthusiastic to buy RTG for your home. With current technology, they can produce a A few hundred watts of power. This may be enough to run the standard laptop, however It is not enough to play video games With a powerful graphics processing unit.

For deep space tasks, these hundreds of watts are more than enough.

The true benefit of RTGs is its ability to provide an expected and consistent power. The radiological decomposition of plutoniumium is fixed – every second every day for decades. For about 90 years, Only half of the plutonium In RTG it will decompose away. RTG does not require moving parts to generate electricity, making them less likely to break or stop working.

In addition, they have Excellent safety recordIt is designed to survive in its natural use and also be safe in the event of an accident.

RTGS at work

RTGS was the key to the success of many solar energy system in NASA and deep space tasks. the Mars is a curiosity and perseverance of Rovers and New spacecraft prospects That visited Pluto in 2015 used all RTGS. New Horizons is going outside the solar system, as RTGS provides energy that cannot be solar panels.

However, there are no tasks that pick up RTGs just like Voyageer tasks. NASA launched Voyageer 1 and Voyageer 2 in 1977 to take a A tour of the outer solar system Then a trip outside it.

Every craft was Equipped with three RTGsAnd providing a total of 470 watts of energy at launch. Nearly 50 years have passed since Voyageer’s investigations are launched, and both are still active scientific tasks, Collect data and send it again to the ground.

Voyageer 1 and Voyageer 2 are about 15.5 billion miles and 13 billion miles (about 25 billion km and 21 billion km) from the ground, respectively, which makes them The most distant things of man -making ever. Even in these extreme distances, their RTGS still provides them with fixed strength.

This spacecraft is a testimony of the ingenuity of engineers who were first designed in the early 1960s.

Benjamin RollstonAssistant Professor of Physics, Clarkson University. This article has been republished from Conversation Under the creative public license. Read The original article.