What is a rocket booster? 

A booster is the first stage of any multi-stage rocket. This is also the most powerful stage because large amounts of thrust are necessary to overcome our planet's gravity and the first dense layers of the atmosphere. After this is achieved, the first stages are discarded, and rockets proceed with the second, less powerful, stages. Depending on each rocket design, there could also be a third orbital booster for in-orbit manoeuvres.

Why is it called a solid rocket booster? 

Depending on the type of fuel a given rocket uses, its boosters can be either liquid or solid. Solid substances power solid boosters; usually, those are some gunpowder derivatives mixed with aluminium as their primary fuel source, while ammonium perchlorate generally acts as an oxidizer. It was solid rocket motors that paved our way to the stars, but originally, they were designed for aircraft jets way back in the 1930s.

If so, who made the solid rocket boosters? The first models were introduced in Germany, but as often happens, the US managed to improve on this technology a bit later, in 1940. Orbital Today reports that the first serial system for aviation, “JATO” (Jet Assisted Take Off), consisted of 36 engines and was used to increase the traction parameters of bombers during WWII. This is when the history of solid rocket boosters officially began, but since then, this technology has come a truly long and miraculous way.

Pros & Cons of Solid Rocket Booster Technology

Development of Solid Rocket Booster

In all honesty, the development of solid rocket booster technology has seen its ups and downs. One of the primary advantages of using a solid booster is that it allows for a very simple engine design where an engine and its fuel tank are combined into a single unit. While such technology is very efficient, it still has several drawbacks, which is why most private companies today choose in favour of liquid engines.

Probably one of the first things that come to mind as far as solid rocket booster disadvantages go is their high accident rate. While in practice, this risk is way lower than it used to be a few decades ago, many still remember the Challenger Shuttle disaster in January 1986, when a fuel tank exploded less than two minutes into the flight, killing the crew and destroying the ship. A more recent tragedy occurred in 2003 in Brazil. This time, the rocket was only preparing for launch, yet a miscalculation led to an explosion that claimed the lives of 21 technicians on site.

Right now, however, it looks like companies have learned from their mistakes, and solid rocket booster technology has been made significantly safer. However, one should not forget that solid fuels are still highly flammable and are prone to ignite on accident. But, lots of leading companies, including Northrop Grumman and NASA, are not ready to forsake solid boosters just yet. Why? Mostly because they are powerful and do not require any complex ground infrastructure. Unlike liquid boosters that need pricey tanks for storing liquid propellants, solid fuels have no special requirements when it comes to storage. 

Does it mean that solid boosters are more affordable than liquid ones? Yes and no. While companies using solid boosters get a chance to downsize on-ground infrastructure and simplistic booster design, they must create a new booster for every new launch. The solid rocket booster can only be ignited once; it cannot be turned down until the whole fuel tank burns out, and, as a result, a stage cannot make a controlled landing — it simply falls down. So, there is no chance of restoring a used solid booster stage, whereas most private companies today, including the undeniable launch leader, SpaceX, are betting on rocket reusability to reduce launch costs.

Will Solid Rocket Boosters Go Away?

Eventually, solid fuel technology may well be discarded, but it does not look like it's happening any time soon. NASA is now working on a new Space Launch System (SLS) to take astronauts to the Moon as part of the Artemis mission. SLS should be a logical continuation of the Space Shuttle Program — with safety and performance improvements, of course. Several other rockets, including Ariane V, Atlas V and PSLV, are also powered by solid fuels. 

So, while this tech has a few downsides, solid rocket boosters are still a reliable and efficient way of sending cargo and people to space.

About the Author

Emma Thorpe is a journalist and freelancer who writes articles about science, space, technology, and the universe. She’s fond of watching stars and exploring space through the telescope at her leisure. Now, Emma is counting down the days until the Orionid Meteor Shower.