Melt the butter in a large nonstick skillet over medium heat. Add the pancetta and saute until crisp and golden, about 5 minutes. Add the onion and saute until tender, about 2 minutes. Add the asparagus and saute until crisp-tender, about 2 minutes. Add the orzo and stir to coat. Add the egg mixture. Using a rubber spatula, stir the mixture until the eggs are softly set, about 4 minutes.
Transfer the egg mixture to a serving bowl and serve.