ISRO  Nuclear Energy for Space Missions.
                     ISRO - Nuclear 
Energy for 
Space 
Missions
Introductio 2
n
UR Rao Satellite Centre (URSC) of 
Indian Space Research Organization 
(ISRO) is going to use Radioactive 
Thermoelectric generators for power 
generation and thermal 
management of various space 
missions.
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Why in the News?
In January 2021, the UR Rao Satellite 
Centre (URSC) of Indian Space 
Research Organization (ISRO) invited 
proposals for the three-phase 
development of a 100-Watt 
Radioisotope Thermo-electric 
Generator (RTG).
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UR Rao Satellite 
centre 
UR Rao Satellite centre is ISRO's lead 
centre for design, development, 
fabrication and testing of all Indian 
made satellites. 
Now it would be using Radioactive 
Thermoelectric generators for power 
generation and thermal 
management of various space 
missions. 
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Radioisotope 5
Thermo-electric 
Generator (RTG)
Radioisotope Thermoelectric 
Generator is a kind of a nuclear 
battery using thermocouple to 
convert the heat released by decay 
of radioactive material into 
electricity. 
Seeback effect governs it, and it 
generally has no movable parts. 
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Seebeck 
effect
The "Seebeck effect" is a 
phenomenon in which a 
temperature difference 
between two dissimilar 
electrical conductors or 
semiconductors produces a 
voltage difference between the 
two substances.
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Stages of 
launching satellite
The normal satellites are launched in 
multiple stages. 
The first stage being the strap on 
boosters and in the second stage 
these are loosened by the satellites. 
The third stage is reached after 
detaching the second stage and 
finally the satellite is sent into space.
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Working benefits of 
RTG
Like other satellites use heavy 
carriers for energy generation 
making the satellites bulky, RTG 
systems  use thermocouples and 
natural decay of radioactive isotopes 
into electrical energy. This makes 
them less bulky. 
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Working benefits of 
RTG Cont.
They are reliable and maintenance 
free because the moving parts in 
thermocouples that cause failure of 
machinery are absent in RTG 
system. 
The RTG systems are more fuel 
efficient than normal satellite 
systems.
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Working benefits of 
RTG Cont.
These are lighter than chemical 
rockets and thus they would travel 
further, faster and would shorten the 
time duration of the trip. 
Since they do not work on solar 
power, they evoke the satellite to 
function on the darker sides of the 
planets.
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Which Systems 11
Require RTG 
Technology?
1. Systems that are unable to be 
continually maintained and 
serviced
2. Systems those are incapable of 
generating solar energy 
efficiently
3. Systems that need to remain 
operating without human aid for 
long durations of time
4. Systems that require minimal 
human interaction
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Design of the RTG
The typical design of an RTG is 
relatively simple and 
straightforward, consisting of two 
crucial ingredients: fuel that will 
decay radioactively and a large set 
of thermo- couples to convert heat 
into electricity.
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Is India the first to 
use RTGs?
No, India is not the first country to 
use the RTG technology, but the 
technology is not very popular. 
The RTGs were for the first time used 
in space after the Cold War in 1961 
for USA's Transit-4A Mission. 
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