Here Are the Space Launch System Solid Rocket Boosters in a Few Hard to Grasp Numbers

Back in August of last year, we tried to give you a glimpse of the numbers behind the insanely powerful Space Launch System (SLS) rocket that is the backbone of the Artemis lunar exploration program. As the launch date of Artemis I approaches, a closer look at two key components of the SLS might be in order: the boosters.
SLS to use two solid rocket boosters 19 photos
Photo: NASA
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As most of you already know, space exploration is at the moment particularly difficult because of only one reason: all our missions have to depart from Earth, and that requires a lot of power, as the planet’s gravity has to be defeated.

As a rocket launches vertically from whatever pad, it has to reach something called escape velocity. That would be the minimum speed needed for the rocket to overcome the gravity pulling it back, and in the case of Earth, that would be a tad over 11 km per second (40,030 kph/ 25,053 mph).

Through trial and error, we humans came to the conclusion that at times, when heavier loads need to be placed in higher orbits, a single core stage rocket is not enough. Hence the boosters were born, long tanks of fuel with engines at one end supposed to assist the ones in the core stage for the first two minutes of flight, when the battle against gravity is at its hardest.

There will be two of them for the SLS as well, powered by engines sourced from the now defunct shuttle program. Standing 17 stories high, each of the two comprises three assemblies.

SLS to use two solid rocket boosters
Photo: NASA
The forward assembly is where the nose cap and forward skirt are located, and the skirt is where the electronics that command the boosters are. Then comes the motor assembly, where five segments filled with propellant can be found. Being solid rocket boosters, the propellant (polybutadiene acrylonitrile) comes in this state as well, and has according to NASA the “consistency of a pencil eraser.”

Last, but not least, the aft section is where another skirt that houses the thrust vector control system is located – this one steers the nozzle based on commands from the booster avionics.

These smaller rockets, because that’s what they are, will provide the SLS with more than 75 percent of its full thrust at takeoff. That would be 3.6 million pounds each (more than 14 jumbo commercial airliners, each with four engines, combined), making for the “most powerful solid propellant booster ever built.” For the record, SLS’ total output in its first incarnation (Block 1) is 8.8 million pounds, which is 15 percent more than the Saturn V rocket that backed the Apollo program.

During their short, two-minute operation, each booster will burn 6 tons of propellant per second, for a total of 756 tons. As soon as the booster tanks are empty, each of them detaches from the core stage, and will fall, as all other boosters always did, back to our planet.

Photo: NASA
At the time of writing, the first time both of them, but also the core stage and the Orion capsule, will be put to the test is sometime in April, when the launch of Artemis I has now been pushed.

The first mission of the new hardware will be one needed to test things, and it will be uncrewed. The SLS, boosters and all, will send the Orion capsule and its two occupants, the Arturo Campos dummy and the Snoopy zero-gravity indicator, on a 26 to 42 days trip to and around the Moon.

If all goes well, NASA will then move to schedule the first crewed mission to the satellite, but it will only be the third flight of the program, probably in the second half of the decade, that will actually put human boost back on the Moon. This time, one of those pairs of boots will wrap around the feet of a woman.
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About the author: Daniel Patrascu
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Daniel loves writing (or so he claims), and he uses this skill to offer readers a "behind the scenes" look at the automotive industry. He also enjoys talking about space exploration and robots, because in his view the only way forward for humanity is away from this planet, in metal bodies.
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