Cook pasta in boiling salted water according to package directions; drain.
Meanwhile, heat a large nonstick skillet over medium-high heat. Add pancetta, and cook 3 minutes or until crisp, stirring occasionally. Remove from skillet, and drain on paper towels. Return skillet to cooktop, and add 2 tablespoons oil, onion, and garlic; cook, over medium-high heat, 5 minutes or until onion starts to soften, stirring occasionally. Add asparagus; cook 2 minutes or until bright green. Stir in peas, and cook 2 minutes. Add vermouth; cook 1 minute or until reduced to a glaze. Stir in tarragon and cook 1 minute. Remove from heat.
Heat remaining 1 tablespoon oil in a separate skillet over medium-high heat. Sprinkle scallops with 1/4 teaspoon salt and 1/8 teaspoon pepper. Add to skillet, and cook 2 to 3 minutes on each side or until browned.
Return large skillet to cooktop. Add cooked pasta and 2 tablespoons butter, and cook 1 minute or until butter melts. Remove skillet from heat, and stir in cheese, half of reserved pancetta, and remaining 1/4 teaspoon salt and 1/8 teaspoon pepper. Divide pasta among 4 bowls, top each evenly with scallops, and sprinkle with remaining pancetta.