by The main goal of the US manned space program right now is to 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 engine in space for the first time. The flight may take place from 2027.
The project is the result of a collaboration between NASA and Darpa, the Defense Advanced Research Projects Agency, the US military’s technology development arm. The civilian space agency will develop the engine itself, and the rest of the spacecraft is up to DARPA.
Nuclear propulsion is considered a key technology to enable repeat trips to Mars. Strictly speaking, it is possible to carry out the missions using only chemical combustion, a technology applied to all rocket stages in operation in the world today. But that means longer travel times, which becomes a problem when we’re talking about keeping people in deep space, exposed to high doses of radiation.
The most efficient transport orbit to the red planet (ie 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 almost 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 does it work? Instead of “burning” the fuel and producing a jet of exhaust that propels the rocket forward, a nuclear thermal engine uses a reactor to heat the propellant to very high temperatures and then launch it, without combustion. The potential ejection velocity is greater than that of combustion, which provides greater thrust. A trip to Mars could be shortened to about three months, and there would be more flexibility in how long one would have to wait before starting the return trip.
The collaborative Nasa-Darpa project, called Draco, is initially targeting the region of the Moon. The acronym, in Portuguese, stands for Agile Cislunar Business Demonstration Rocket. The idea is to make the US capable of rapid maneuvers across the globe between Earth and the Moon – a capability that is becoming strategically important as the region becomes a subject of interest to many 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 issue has always been controversial – after all, the safety level for launching a small nuclear reactor on top of a rocket needs to be as high as possible. Now it seems that 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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