What is the effective exhaust velocity in a Space Shuttle Vacuum?
CREATE TABLE "specific_fuel_consumption_sfc_specific_i" (
  "engine_type" text,
  "scenario" text,
  "sfc_in_lb_lbf_h" text,
  "sfc_in_g_k_n_s" text,
  "specific_impulse_s" real,
  "effective_exhaust_velocity_m_s" real
);
SELECT COUNT("effective_exhaust_velocity_m_s") FROM "specific_fuel_consumption_sfc_specific_i" WHERE "scenario"='Space shuttle vacuum';