101 on Rocket Boosters: Technical Specifications and Types

Today, when rocket launches have become a commonplace event, few people wonder what it takes to raise a giant launcher into the air and deploy its payload into a calculated orbit. Of course, the details will depend on the exact launch vehicle type, but escaping our planet’s gravity would not be possible without a rocket booster. This article will answer the question — what is a rocket booster? More importantly, why is it so important in today’s space technology?

Rocket Booster Types Explained

A rocket consumes most fuel during its initial stages of flight because, besides the required energy to take off from the ground, all launch vehicles also need to overcome our planet’s force of gravity. A booster also called the first stage, is responsible for these crucial stages of launch.

Of course, depending on the launcher and rocket booster technical specifications, some details may differ. For example, some boosters are designed as smaller side rockets flying in parallel with the main carrier. Or, when a multi-stage launcher needs to accurately deploy its payload into the calculated orbit, it uses an upper (usually third) stage, also called an orbital rocket booster.

However, the most basic classification of boosters depends not on their design and placement in the main launcher but rather on the type of fuel these rocket boosters use. Fuel can be either liquid or solid, so let’s take a better look at their differences.

Solid Rocket Booster Pros & Cons

Rocket Booster

Solid rocket boosters were originally designed for aviation bombers during WWII, but less than two decades later, they found their way into space technology. Considering when this tech was developed, it’s no wonder that the whole construction is relatively simple. Usually, a solid rocket booster consists of a solid propellant engine and a fuel tank neatly arranged in one package.

But what type of solid rocket fuel is now used? Typically, aluminium serves as the primary fuel source mixed with an oxidizer (ammonium perchlorate in this case), and polybutadiene (HTPB) to bind those two components together. Modern aviation has no need for solid boosters anymore, but several heavyweight rockets (Ariane 5, Delta IV, Atlas V) still rely on this rocket tech. The NASA Space Shuttle program also used solid rocket boosters, and it was during one of those missions that these boosters’ biggest advantage was tragically discovered — solid rocket fuel can ignite by accident, resulting in crew death and shuttle destruction.

On a more positive note, the Shuttle issue was fixed, and today’s solid rocket boosters are designed with safer and less toxic materials. Also, according to Orbital Today, they are very simple in the operation, which is not always the case with newer counterparts running on liquid fuel.

Liquid Boosters: Future of Space Travel, According to Private Launchers

Even though most present-day private launchers rely on liquid propellants, this technology also has a long history. Thanks to liquid fuels and boosters, the first artificial satellite and the first astronaut accomplished their space mission goals. Many modern liquid rockets still use the combination of kerosene as fuel and LOX as oxidizer — the same combo that took the first Soviet tech and people to space.

However, there are other, more affordable, and less toxic counterparts to replace kerosene today. Still, affordability and environmental friendless are not the only reasons why so many private companies today (SpaceX, Rocket Lab, Skyrora, Orbex) bet on liquid boosters.

First, liquid fuel is less likely to ignite on its own, which means it is way safer for manned flights. Then, unlike solid fuel, a liquid booster can be reignited multiple times, ensuring a more controlled flight environment and lower fuel consumption. For the same reason, liquid boosters can be reused because their trajectory can be adjusted during descent. Finally, liquid boosters are more compact and lightweight, which, once again, increases launcher functionality.

But there is a downside to everything. Liquid engines are more compact, but they call for a larger and more complex ground infrastructure — fuel storage tanks, complex supply systems, etc. So, at this particular point, we can safely conclude that both liquid and solid boosters are in demand. Still, it already looks like liquid propellants will eventually take over solid ones— mostly because only liquid rocket stages can be reused. 

At this point, you may wonder — what are rocket boosters made of? The same metal composites as the rest of the rocket — regardless of the fuel type this rocket may need. And the final logical question is — if we still use liquid and solid fuel, what are different types of rockets used for? The answer to that will depend on the launch operator, spacecraft designs, and budgets. For example, NASA is betting on solid fuel in its upcoming Space Launch System. According to the plan, SLS should improve on Space Shuttle tech, surpass it, and eventually take astronauts to the Moon. But private players, particularly Rocket Lab and SpaceX, prefer liquid fuel for advanced manoeuvrability in orbit.

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