Chapter 376 - 368 DARPA_1

SpaceX placed high importance on its Starship development, the thrust of 33 Raptor 1 engines was undoubtedly the second strongest in the world, and if the pressure in the combustion chambers was increased, it might even be possible to achieve a thrust of over 7000 tons, on par with the New Yuan No. 3 rocket.

However, aside from the development of the Raptor series engines, SpaceX also planned to try out new tracks.

"Hello, I’m Wayne."

"Nice to meet you, Wayne."

Musk and his close partner Tom Mueller greeted a young Caucasian man who, clearly not to be underestimated, held his own with confidence.

Wayne: "I believe you already know why we’re here."

Musk: "You’re from DARPA, the Defense Advanced Research Projects Agency."

DARPA, almost a private company under the military’s control from the Pentagon, openly researched nuclear propulsion technology.

The nuclear-powered engine originally planned for the FATS project was intended to be handed over to DARPA, but NACA took the initiative to set up the JFT, making DARPA a collaborative researcher for the JFT responsible for the design and production of parts for the nuclear thermal engine.

This was not a small order, but DARPA was not satisfied. Plus, with Storm constantly provoking the Air Force, they took the initiative to propose a new plan for the Department of Defense.

Wayne: "The military is currently being led by the nose. The Space Shuttle completed all its missions from 1981 to 2011, in those thirty years. It was merely a pursuit of SSTO, but in reality, it was far inferior, both in terms of utility and economy.

Initiating the nuclear-powered spacecraft program was correct, but the idea of a nuclear-powered Space Shuttle is absurd, especially when relics from museums are being rolled out. What we need are bigger, heavier, more expensive goodies."

Tom Mueller immediately knew what they wanted to do.

"Starship, Starship can meet your requirements."

Wayne: "Yes, it has a mass close to a thousand tons, ten times that of Endeavour. We can install more and larger nuclear engines on it, as well as unimaginably powerful superweapons. It can carry at least a few hundred tons of payload, right?"

Musk quickly nodded. The most commendable aspect of Starship’s second-stage orbital entry plan was the in-orbit mass, but there definitely wasn’t a few hundred tons of payload – the total mass would surely be under 300 tons, with a 150-ton payload being good enough.

But how could he speak discouraging words at this time? Besides, the Starship was upgradeable!

"That’s no problem at all, and Starship isn’t expensive. Even the final official version only needs half the heat shield tiles, and the manufacturing costs won’t exceed 200 million US dollars. However, it requires over a thousand tons of thrust to reach orbit, can the nuclear engine provide that amount of thrust?"

Wayne: "One is enough."

"I’ve seen your Moon and Mars plans. Refueling multiple times is indeed troublesome and difficult. But with nuclear engines, you simply need to fill up fuel in a near-Earth orbit, and then you can easily embark on interstellar travel.

DARPA is willing to fund Starship if you agree, and we’ll initiate a proposal next month. The total R&D costs of Starship haven’t reached 3 billion US dollars yet, have they? Just one of DARPA’s sub-projects can exceed that figure."

This was almost a hint that the forces behind DARPA really weren’t short of money. In reality, as a newcomer supported by NACA, SpaceX wasn’t well-received by the old military-industrial consortium. But standing with DARPA meant standing alongside the big shots at the Pentagon.

They could bring an unimaginable budget, and though they would take a cut as compensation, it would still be plenty for SpaceX.

...

"We’re short-staffed, not enough, not enough. We need at least 10 B+ or, preferably, Level A researchers for this to work."

Ye Changsi was flipping through a stack of densely printed pages under the light, which wasn’t much thinner than "Introduction to Radiation Propulsion Technology," and Cheng Nankai was facing a similar situation.

"Introduction to Radiation Propulsion Technology" had been scanned and printed into several PDF copies, but now they were only allowed to be kept in the basement – these materials were just too important.

The two atomic technology experts, along with five assistants, spent three days in the basement, nearly devouring the book.

This internal journal from the future was incredibly valuable. The first part’s introduction and the collection of related papers at the end were the most important. They revealed to the two men what the truly viable and efficient methods of nuclear fusion were like in the future, particularly the crucial theoretical part, which filled in the final piece of the puzzle in the field of fusion.

The most impressive was the "Yu Qian Formula." The Yu Qian of this world line, a real genius not yet existing, actually used the weak interaction force to solve the problem of uncontrolled plasma during fusion, making continuous reactions difficult to sustain and advancing the unification of the four natural forces (strong force, weak force, electromagnetic force, gravity) by a significant step, ranking him with the likes of Einstein and Bohr.

As for the second and third parts on nuclear fusion propulsion technology, there are three types: plasma propulsion, radiation propulsion, and electric propulsion.

Plasma propulsion is similar to a fission engine, heating a working fluid (water, hydrogen, methane, and other molecules) into plasma and then ejecting it at high speeds. The only difference is that fusion engines can provide temperatures of tens of millions, or even hundreds of millions of degrees, resulting in greater ejection speeds and the use of larger molecular weight fuels.

This technology is theoretically refined and has extensive prior experience. However, its downside is the rapid consumption of fuel, making interstellar travel unfeasible;

Electric propulsion is essentially the Hall Thruster, meaning the nuclear fusion device is used to generate electricity, and then uses an electromagnetic field to accelerate ions to ultra-high speeds and eject them. It’s like a high-powered electric push from nuclear power with a very high specific impulse that can exceed 100,000 seconds, and consumes very little fuel. Although it has a small thrust and potential for interstellar travel, it has slower acceleration and higher requirements for the accelerating working fluid;

Radiation Propulsion Technology is divided into passive radiation propulsion, where the spacecraft/probe equips a receiver similar to the Solar Sail and is irradiated by a super-large radiation stimulation device within the Solar System, using lasers, alpha particles, etc., as the power transmission medium and does not require additional propellants, raising the potential for impulse over electric propulsion by a hundredfold or more;

The second is active radiation propulsion, meaning the radiation propulsion generated on the spacecraft itself, which is the most ideal configuration for a spaceship. Theoretically, it can reach sub-light speeds and matches the spaceships seen in dreams.

Plasma propulsion and electric propulsion are technologies already mastered by humanity. Applying fusion technology to them is not complicated, but as for radiation propulsion... According to the original author Zhao Zongyao’s estimate, it should be practical within about two hundred years.

Two hundred years because radiation propulsion is just too ideal—although photons or alpha particles can be accelerated without the need for a propellant, leading to unimaginably high specific impulses, the actual difficulties are extremely high.

Photons have no mass but can indeed generate radiation pressure; humanity has already conducted Solar Sail propulsion experiments, and alpha particles should work too. However, the problem is these two things have so little mass they are almost negligible. Following the original momentum formula, the thrust obtainable with current means might not even compare to electric propulsion.