Sidereal Messenger: NASA starts creating nuclear propulsion for trips to Mars

The main focus of the American manned space program right now is the return to the Moon. But NASA is already taking the first steps to make a trip to Mars possible. Last Tuesday (24), the US space agency announced an agreement to test a nuclear-powered engine in space for the first time. The flight can take place from 2027.

The project is the result of a partnership between NASA and Darpa, the Defense Advanced Research Projects Agency, the American military arm of technological development. The civilian space agency will develop the engine itself, and the rest of the spacecraft is up to DARPA.

Nuclear propulsion is seen as a key technology to enable recurring trips to Mars. Strictly speaking, it is possible to carry out the missions using only chemical combustion, technology applied in all rocket stages in operation in the world today. But this implies longer travel times, which becomes a problem when we are talking about keeping humans in deep space, exposed to high doses of radiation.

The most efficient transfer trajectory to the red planet (that is, the one that requires less propulsion) takes 8 to 10 months of travel. Once there, a crew would have to wait 10 to 12 months on Mars for the planets to align for the return, which would take another 8 to 10 months. In the end, it would be nearly three years round trip. Even discounting radiation and microgravity, it’s not easy to get supplies on board to sustain a crew for three years.

With nuclear propulsion, this equation would change radically. How it works? Instead of “burning” the fuel and producing an exhaust jet that pushes the rocket forward, a nuclear heat engine uses a reactor to heat the propellant to very high temperatures and then eject it, without any burning. The possible speed of ejection is greater than that of combustion, which ensures greater thrust. A trip to Mars could be shortened to something like three months, and there would be more flexibility on how long one had to wait before starting the return trip.

The Nasa-Darpa cooperation program, called Draco, at first targets the vicinity of the Moon. The acronym, in Portuguese, means Demonstration Rocket for Agile Cislunar Operations. The idea is to make the US able to perform rapid maneuvers across the entire sphere between Earth and the Moon – a capability that is becoming strategically important as the region becomes the object of interest for multiple countries, notably China.

The space community has heard about nuclear propulsion for many decades. There have been other experimental programs in the past, but the topic has always been controversial – after all, the safety level for launching a small nuclear reactor on top of a rocket has to be as high as possible. Now it looks like the right combination of boldness, reliability and necessity will make this transformative technology a reality. To check.

This column is published on Mondays in Folha Corrida.

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