Yes. A few approaches can help:

• Use AF-S (single-servo AF). In AF-S, a half-press acquires focus and then holds it as long as you keep the shutter button half-pressed, letting you fire additional shots faster.
• Use focus lock via the AE-L/AF-L button. You can focus once, then lock focus so the camera won’t refocus on each shot. Depending on settings, this may also lock exposure.
• If your D5100 allows it, assign autofocus to a back button so the shutter button only meters and shoots, while autofocus happens only when you press the rear button. This is often called “back-button focus.”
• Another option is AF-C (continuous AF), which typically allows release priority, meaning the shutter can fire without waiting for focus confirmation.

For a stationary subject like the moon, AF-S or focus lock/back-button focus are usually the simplest solutions.