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<\/figure>\n<\/div>\n\n\nSatellites and probes<\/h2>\n\n\n\n
The aim is to power the instrumentation of terrestrial satellites and planetary probes with slightly more powerful generators so that they can reach nearby planets and transmit information back to Earth.<\/p>\n\n\n\n
Isotopic power generators are instruments containing a hermetically encapsulated radionuclide whose radiation is absorbed in the walls of the capsule. This is the equivalent of a heat source since the capsule transforms the energy of the radiation. An electrical circuit is coupled to this source to generate an electric current to power the instruments.<\/p>\n\n\n\n
The source will be long-lived if the half-life of the radioisotope is long and the radionuclides used are always alpha emitters because this radiation is stopped in the first microns of the walls of the later stages, e.g. for travel to Mars, the process is capsulated (usually stainless steel). Preferably plutonium-238 and curium-244 are used, which can provide small electrical powers for many years.<\/p>\n\n\n\n
The European Space Agency is studying the replacement of plutonium-238 with another isotope that generates electricity to meet the needs of electrical and electronic equipment for measuring and transmitting data to Earth. One of the isotopes under consideration is americium-241, commonly used in fire detectors, also an alpha emitter with a similar decay value to plutonium-238, but with a half-life of 432.2 years, which can be used for longer missions, although a larger quantity will be required to achieve the same energy.<\/p>\n\n\n\n
Spacecraft propulsion<\/h2>\n\n\n\n
For the foreseeable future, spacecraft launched into space will continue to rely on fossil fuels for propulsion. However, once in orbit, nuclear engines could take over and create propulsion to accelerate speed.<\/p>\n\n\n\n
Unmanned travel to planets outside Earth's solar system has been accomplished by missions equipped with robotic equipment powered by electricity produced by the radioisotope plutonium-238. This isotope has a half-life of 87.74 years and an activity lifetime that can practically serve the needs of space missions for several centuries. Plutonium-238, which is not fissile like other plutonium isotopes, has its origin in irradiated uranium fuels. They would work by transferring heat from the nuclear reactor to a liquid propellant, which would be converted to gas and expand to provide thrust for the spacecraft.<\/p>\n\n\n\n
There are two key nuclear technologies for propulsion: With thermonuclear propulsion, there is less fuel load and a trip to Mars would be shorter. With electronuclear, the fuel efficiency is much higher and the trip would be even shorter.<\/p>\n\n\n\n
Thermonuclear propulsion (NTP)<\/strong><\/p>\n\n\n\n It involves using a nuclear fission reactor to heat a liquid propellant, such as hydrogen. The heat converts the liquid into a gas that expands through a nozzle to generate thrust and propel the spacecraft.<\/p>\n\n\n\n One of the main advantages is that spaceflight would require less refuelling, and NTP engines would make the trip shorter. For example, a trip to Mars would be reduced by 25% compared to traditional chemical rockets. In addition, reduced time in space also reduces astronauts' exposure to cosmic radiation.<\/p>\n\n\n\n Electronuclear propulsion (NEP)<\/strong><\/p>\n\n\n\n Thrust is produced by converting the thermal energy of a nuclear reactor into electrical energy. With this type of technology, thrust is lower but continuous, and fuel efficiency is much higher. The speed is increased, with a reduction of more than 60 % in transit time to Mars compared to traditional chemical rockets.<\/p>\n\n\n![\"Fuente:](\"https:\/\/rinconeducativo.org\/wp-content\/uploads\/2024\/11\/VASIMR_Ad-Astra-Rockets.jpg\")
![\"El](\"https:\/\/rinconeducativo.org\/wp-content\/uploads\/2024\/11\/Reactor-PFRC_Lab.-Fisica_Plasma_Pricenton.png\")
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