The Iₛₚ Trap

NASA is still struggling with hydrogen leaks on the SLS rocket. They missed another launch. This is what happens when you follow a "number" instead of real-world physics.

The Iₛₚ Myth

In school, they teach that Specific Impulse (Iₛₚ) is everything. Hydrogen has a high Iₛₚ (~450s). Methane is lower (~380s). NASA stays with Hydrogen because of this one number.

But in the real world, Iₛₚ is a trap. Here is why:

Hydrogen is "Fluffy": It has almost no density. To get enough mass, you need giant tanks.

The "Dead Weight" Penalty: Because the tanks are huge, the rocket is heavy. Even when the fuel is 90% gone, the engine is still pushing a giant, empty metal balloon. This eats all the Iₛₚ gain!

The Leak Problem: Hydrogen is the smallest molecule. It finds every tiny hole. It makes metal weak (embrittlement).

The Methalox Solution

NASA should have switched to Methalox (Liquid Methane + Oxygen) decades ago. Methane is 6 times denser than Hydrogen. The tanks are small and strong. At the "finish line," a Methalox rocket is much faster because it isn't pushing a giant empty house.

No Excuses on Infrastructure

Some say it is too expensive to change the launch pads. This is not true. If a pipe can hold Liquid Hydrogen at -253°C, it can easily hold Liquid Methane at -161°C. Methane is "warmer" and easier to handle. Switching to Methane is a "downgrade" in difficulty.

Wasting Taxpayer Money

It is not just about the physics; it is about the people's taxes. Liquid Hydrogen is incredibly expensive. When you compare them in liquid form, the cost difference is huge. Liquid Methane is abundant and cheap. Liquid Hydrogen requires massive amounts of electricity to reach extreme cold. Why spend billions of tax dollars on an expensive setup that does not work properly? It is dangerous and hard to handle. Other than a "theoretical" Iₛₚ number, hydrogen has no advantage. It only has "show-stopper" disadvantages. NASA is stuck with "Academic Blinders." We are in the age of robotics, yet we risk lives on a "leaky hydrogen bomb" just because leaders won't admit they are wrong. The periodic table is simple. Real-world physics matters more than a textbook number.