Why don't NASA rockets have fins?

Answer 1

Although some rockets still use short fins to stabilize their flight, many rockets use a computer-controlled movement of their engine nozzles. The directional thrust is balanced to achieve the proper trajectory. Another way to maintain even vertical thrust is by a slow roll or spin.

Answer 2

NASA rockets don't have fins because their design is based on stability achieved through thrust vectoring and engine gimbaling instead. This allows for greater control and maneuverability during flight without the need for fins. Fins can add unnecessary weight and complexity to a rocket design, so NASA opts for more streamlined and efficient solutions.