Nuclear batteries on space probes

In summary, it is desirable for the heat source in a Radioisotope thermoelectric generator (RTG) to not emit a lot of gamma radiation. This is because gamma rays can harm electronics and induce nuclear reactions. The use of low gamma emission radio isotopes, such as Plutonium 238, is preferred for better heat to electricity generation efficiency. In space probes, the RTG is often located at the end of a long boom to minimize exposure to the rest of the craft. However, with advancements in RTG technology, they are now often placed closer to the main body of the spacecraft.
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nmsurobert
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I've been reading about this a bit and stumbled across something that said its desirable that the heat source not be something that emits a lot of gamma radiation.
Other than hazards to a technician, does this have any effect on the device its being used on? Why would it require extra shielding if its out in space?

Thanks.
 
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The radiation could affect the electronics being powered.
 
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jedishrfu said:
The radiation could affect the electronics being powered.
thats what i was thinking but i wasn't sure. maybe the gamma ray just passes on through the electronics.
my initial thoughts were that they wanted a lot alpha particles hitting the inner walls of where the heat source is to create heat but i wasn't sure.
thought id ask the pros.
 
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Gamma rays are harmful to electronics, and if they have high energies they can induce nuclear reactions harmful to basically all materials (although you need a very high dose before that becomes relevant).
 
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mfb said:
Gamma rays are harmful to electronics, and if they have high energies they can induce nuclear reactions harmful to basically all materials (although you need a very high dose before that becomes relevant).
would a gamma emitter generate less heat because of gamma rays ability to easily pass through objects?
 
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A part of that energy is lost, sure.
The difference in overall activity is more important than that.
 
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mfb said:
A part of that energy is lost, sure.
The difference in overall activity is more important than that.
awesome. thanks guys.
 
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In addition to damaging the control system's electronics, the gamma rays may increase baseline noise in the probe's sensors. That would be bad...
 
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nmsurobert said:
I've been reading about this a bit and stumbled across something that said its desirable that the heat source not be something that emits a lot of gamma radiation.
Other than hazards to a technician, does this have any effect on the device its being used on? Why would it require extra shielding if its out in space?

Thanks.
Calling them batteries as in your thread title isn't really a good description. These units are called Radioisotope thermoelectric generators, RTG's and get used on spacecraft and also for remote location terrestrial power.

The radio isotopes used have been chosen specifically for their low gamma and neutron emission. Plutonium 238 is a common one used particularly because of high alpha emission and low gamma emission during decay. High alpha emission is desirable because of it's much higher heat production which equals better heat to electricity generation efficiency using the thermocouples.

In the early space probes like the Pioneer an Voyager ones, the RTG was often located at the end of a long boom well away from the
rest of the craft...

on the Voyagers' they were like this ...

upload_2017-11-7_12-55-8.png


the RTG's on the boom facing downwards
the magnetometers were on an even longer boom that can be seen heading towards the lower left of the image.
with the passing years development of RTG's has improved and are now often much closer to the main body of the space craft

on the New Horizons craft you can see the two RTG's sticking out on the left side...

upload_2017-11-7_13-4-28.png


a couple of other resources ...

https://solarsystem.nasa.gov/rps/rtg.cfm

https://en.wikipedia.org/wiki/GPHS-RTG
cheers
Dave
 

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Related to Nuclear batteries on space probes

What are nuclear batteries and how do they work?

Nuclear batteries, also known as radioisotope thermoelectric generators (RTGs), are devices that convert the heat produced by radioactive decay into electricity. They work by using a thermocouple, which is made of two different metals that are connected at two junctions. The heat from the radioactive material causes one of the junctions to be hotter than the other, creating a temperature difference that produces electricity.

Why are nuclear batteries used on space probes?

Nuclear batteries are often used on space probes because they can provide a reliable source of power for long periods of time, even in harsh environments. Unlike solar panels, which can only generate electricity when exposed to sunlight, nuclear batteries can produce electricity continuously, making them ideal for missions that require long-term power.

What type of radioactive material is used in nuclear batteries?

The most commonly used radioactive material in nuclear batteries is plutonium-238. This isotope has a half-life of 87.7 years, meaning it will continue to produce heat for many years, making it a reliable source of power for space missions.

Are nuclear batteries safe for use on space probes?

Yes, nuclear batteries are considered safe for use on space probes. They are designed with multiple layers of protective shielding to prevent any radiation from escaping, and they are also tested extensively to ensure their safety before being used in space missions.

What happens to nuclear batteries after they are no longer needed on a space probe?

After a space probe has completed its mission, the nuclear battery is typically left in orbit or sent into deep space. This is to prevent any potential harm to Earth's environment or inhabitants. In some cases, the battery may be intentionally directed towards the sun, where it will be destroyed by the intense heat and radiation.

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