​After a half-century hiatus, NASA and DARPA (Defense Advanced Research Projects Agency) will collaborate in the coming years to create a nuclear engine. This type of rocket engine will significantly shorten the journey to Mars for future crews that will travel to the neighboring planet. Currently, the fuel used in space exploration uses either chemical propellants (in the early stages of launch) or ion propellants (in the advanced stages of a mission, when the probe is in interplanetary space).

It has been more than 50 years since NASA last tested nuclear-powered rocket engines: after abandoning the Saturn V rocket used in the Apollo missions, NASA focused more on developing the space shuttle and easy access to orbit, abandoning the idea of ​​building a rocket with nuclear engine.

A nuclear rocket engine requires a gas (usually liquefied and of low molecular weight, so hydrogen is the best candidate) that expands on contact with a heat source and is then ejected under high pressure, as in the case of a chemical engine (the classic one used today). thus the momentum is transferred to the spacecraft. The difference is that the source of heat is a nuclear fission reactor, rather than a chemical reaction between the fuel and oxidizer, as is currently the case in rocket engines.

According to preliminary studies by the US space agency, such a nuclear engine can be 2-3 times more efficient than a chemical one. Now, after abandoning space shuttles, interest in long-term space travel, that is, to Mars, has returned, and NASA is directly interested in such an engine.

A nuclear engine would significantly shorten the journey to Mars, meaning that the crew aboard the spacecraft would be exposed to harmful cosmic radiation for a shorter period of time during the journey to the Red Planet. In cooperation with DARPA, such a nuclear engine will be designed, built and tested in orbit around 2027.

Although such engines have been tested on Earth before, this will be the first time a nuclear engine has reached outer space. Putting a nuclear reactor into orbit is a touchy subject these days (due to the risk of a failed launch), but it wouldn’t be the first time: the USSR had previously launched several military satellites with a nuclear reactor. for power generation, and some current interplanetary missions (including the Curiosity and Perseverance rovers) use a thermoelectric generator with a radioactive isotope.

This is not the only NASA project that explores nuclear technology for use in space exploration: together with the United States Department of Energy, NASA wants to develop the use of nuclear energy for future bases that will be built on the surface of the Moon or on Mars. .

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