Nuclear-based systems can have less mass than equivalent power solar cells, allowing for more compact spacecraft that are easier to orient and steer in space. In the case of manned spaceflight, nuclear power concepts that can power both life support and propulsion systems can reduce both cost and flight time. Nuclear propulsion includes a wide variety of propulsion methods that use some form of nuclear reaction as the primary energy source. The idea of using nuclear material for propulsion dates back to the beginning of the 20th century.
In 1903, it was hypothesized that radioactive material, radium, could be a suitable fuel for engines to power cars, planes and ships. Wells picked up this idea in his 1914 work of fiction The World Set Free. Nuclear propulsion systems will not activate during launch. Despite the name, nuclear-powered and manned spacecraft will have a large asterisk; they will be launched with chemical propulsion systems.
The nuclear reactor will only work once the vehicle has left the Earth's atmosphere. This design feature is intended to minimize the risk of release of radioactive materials in the event of an accident on the launch pad. Nuclear reactors use controlled nuclear fission in a chain reaction. With the use of neutron absorbers, the reaction rate is controlled, so the power depends on the demand.
The Cassini spacecraft was carrying three RTGs that provided 870 watts of power from 33 kg of plutonium oxide 238 while exploring Saturn. And so, the satellite was equipped with a small, efficient but powerful nuclear reactor, powered by approximately 50 kg of weapons-grade uranium 235.In early 1959-73, there was a United States nuclear rocket program, the Nuclear Engine for Rocket Vehicle Applications (NERVA), which focused on replacing nuclear energy chemical rockets for the later stages of launches. After a lapse of several years, there has been a resurgence of interest in the use of nuclear fission energy for space missions. Uranium used in commercial power plants is usually enriched by up to five percent, which is insufficient for nuclear propulsion systems.
Both will take you from A to B, but a Prius will get you there more efficiently, while a Corvette will get you there quickly using more gas, Ahmed said of the difference between nuclear and chemical propulsion systems for space travel. In addition to solar panels and batteries, a nuclear power source will be installed in the rover so that it can operate up to 400 kilometers, even in the shade. However, nuclear electric propulsion systems are also expected to be much more efficient than traditional chemical propulsion systems. The argument in favor of nuclear space propulsion depends entirely on the supposed imperative of sending humans to Mars.
Nuclear propulsion systems for space exploration, if they materialize, are expected to offer significant advantages, including the ability to send spacecraft further, in less time and more efficiently than traditional chemical propulsion systems. In the late 1980s, the focus was on nuclear electric propulsion (NEP) systems, where nuclear reactors are a source of heat for ion electrical units that eject plasma from a nozzle to propel spacecraft that are already in space. However, attaching what is equivalent to a nuclear reactor to a human-occupied spacecraft is not without risks. Heatpipe Power System (HPS) reactors are compact, fast reactors that produce up to 100 kWe for about ten years to power a spacecraft or planetary surface vehicle.
NASA would also need to design the spacecraft to protect astronauts from the nuclear reactor itself, this could be done by using advanced materials to protect them from radiation or placing homes as far away from it as possible. A more radical goal of Prometheus was to produce a space fission energy system (SPF) such as those described above, both for power and propulsion, that was safe to launch and that would operate for many years at a much higher power than RTGs. Nuclear propulsion systems will incorporate physical shields into their engineering designs, says Calomino. .