To get career mode, create a new world, and name it "Test Career."
The Solid Rocket Boosters (abbreviated as SRBs) are engines that are designed to boost the rocket to help reach space. They contain solid fuel inside it, instead of liquid fuel. Once ignited, they cannot be throttled or stopped until they run out of solid fuel.
They are available in two sizes, one is the size of a 4×5 fuel tank, the other is the size of the 4×9 fuel tank, and one for the Space Shuttle. It cannot be skinned.
Six more solid rocket boosters are planned fore the 1.6 update, with various sizes ranging from 3-wide to 6-wide. They will most likely also have efficiencies ranging from 60 to 80 s.
Career[]

An image of the nozzle heat effect on the new 1.6 boosters.
The 4×5 variant is free, the 4×9 variant is accessible upon enough funds and researching.

Small SRB in-flight. The Plume is similar to the Hawk or Titan Engine's plume.
Trivia[]
- As of January 29, 2022, both SRBs are named just "Solid Rocket Booster". However, in blueprint file, they have names: "Booster Tut 1" and "Booster Tut 3".
- As of June 2023, SRBs are only available in career mode.
- Solid rocket boosters can heat up things even when they are turned off. This was fixed in version 1.5.5.2.
- Before version 1.5.8.5, Solid rocket boosters have a small time delay between being tapped and igniting which can be extended by tapping on more SRBs.
- SRBs have a similar flame to the Hawk Engine flame.
- There is a variant that it is from the SRB of the Space Shuttle. It appeared on the SFS Steam Beta Version, but it's currently under development.
- The Solid Rocket Booster was based on the Space Shuttle's and SLS' boosters.
- Solid Rocket Boosters in real life slowly become less powerful as they run out of fuel.
- They are also called "Solid Rocket Motors".