NASA has two nuclear propulsion energies on the table with which it aspires to make a difference in manned missions to Mars

To take manned missions to Mars requires energy. Plenty and efficient. Saying it is easy; meet the challenge, not so much. In its quest to meet that challenge and clear the difficult path to the red planet, NASA appears to be paying serious attention to nuclear power. On the table you already have two technologies for its rockets with which it aspires to make a difference in the next space missions and, specifically, the race to Mars: nuclear thermal propulsion and nuclear electric propulsion. Both offer advantages such as fuel, logistics and time savings.

What do they consist of one and the other?

Broadly speaking, the first – nuclear power – works in a similar way to chemical propulsion, although changing the combustion chamber for a nuclear reactor that heats a cryogenic propellant. The system would operate like a shuttle, with a rocket that docks with other transport elements. The second, nuclear electric propulsion, is more like a nuclear power plant like the ones we find on Earth, with fission reactions to generate electricity which, in turn, can be harnessed to power a system similar to the one used by la nave Dawn of the space agency using, where appropriate, solar energy.

Evaluate advantages and disadvantages

Each of the options has its pros and cons, of course. as detailed Scientific American, nuclear power requires a huge volume of cryogenic propellant which will likely require orbiting storage tanks. Another of its main handicaps is the enormous temperature it will generate. Of course, precisely because of the characteristics of the propulsion system, the missions would have to start it up for relatively short periods of time.

Nuclear electric propulsion, which presents a more complex system, however requires a longer operating time. Being less developed, its performance level is not fully adapted to those required for Mars and the ship that incorporates it would in any case need a small initial “push” with a chemical propulsion system at key moments of the journey, such as leaving Earth or entering and leaving the orbit of the red planet.

Of the two options, the one that seems better positioned in the race to achieve manned missions to Mars is nuclear thermal propulsion. Half a year ago, in fact, the US Congress appropriated $110 million to NASA to advance in the development of a new nuclear rocket with this type of technology capable of transporting cargo and crew on interplanetary trips.

Also the National Academies of Sciences, Engineering and Medicine (NASEM) point to it as the most appropriate approach in the study that it has undertaken after receiving a commission from NASA itself in 2020. The thermal also has another important plus: the experience accumulated by the US itself in the middle of the century past with experiences like Project Rover.

What seems clear is that NASA seeks to make a difference with nuclear energy, especially for goals as ambitious as establishing a base on the Moon or send manned missions to the red planet. NASA’s tentative timetable calls for a nuclear-powered cargo launch to Mars as early as 2033 and a human mission in 2039 that would require a round trip of about two years. Among other things, this type of energy would avoid the number of flights required to carry fuel that would be necessary with conventional technology.

During a trip to and from the red planet, a chemical propulsion system would require, according to the calculations of Scientific American, raise from the Earth between more than twice and almost 10 times the tonnage of the International Space Station (ISS). Although the current launch systems are replaced by more profitable ones, such as the Starship, which allows its reuse, and the mass that can be transported is increased, a mission to the red planet with chemical fuel propulsion would represent a high cost. The total mass that nuclear propulsion would require is, however, much lower and would be more or less the equivalent of approximately one or two ISSs.

The system would be more efficient and would shorten times. As MIT points outNuclear power has powered rockets for decades, but improving the technology is essential for spacecraft to reach greater distances and speeds. Among the options on the table, the center points to the creation of a powerful fission reactor or the development of a fusion engine.

In 2013, a group of researchers from the University of Washington financed by NASA were working on a nuclear fusion engine that, according to those responsible, would allow trips to Mars to be made within a period of between one and three months, depending on the conditions that prevail. found the ship, times in any case very inferior those driven by propulsion motors. A year ago a similar term, of 30 days, from Princeton was pointed out.

Experts point out that in order to achieve the goal of carrying out nuclear-powered cargo flights by 2033, key to positioning materials and serving as a simulation for manned missions, it is urgent to face critical decisions. One of the challenges they face is arduous bureaucracy that requires launching nuclear materials into space, especially when the fission system is based on highly enriched uranium, something that even requires the formal approval of the White House.

There is steady progress, in any case. Less than a year ago the Defense Advanced Research Projects Agency (DARPA) The US announced its plans to put a nuclear rocket into orbit as early as 2025, a thermonuclear propulsion vehicle that is part of the DRACO program (Demonstration Rocket for Agile Cislunar Operations).

DARPA’s objective is to test a thermonuclear rocket propulsion system in a short time and with a great added advantage: given its characteristics, would minimize ground testing and it would save the complex bureaucracy that could delay deadlines and costs. Tests will be carried out, of course, but the first time the reactor is turned on it will be in space. The US is by no means alone in working on nuclear technology. In 2018, the Russian agency Roscosmos also reported its plans to resume old projects in order to develop a nuclear-powered rocket that would allow it to travel interplanetary.

Via | Scientific American