specific orbital energy of −0.5 mj/kg is what altitude above the earth's surface?
CREATE TABLE "escape_velocities_at_altitude" (
  "orbit" text,
  "center_to_center_distance" text,
  "altitude_above_the_earth_s_surface" text,
  "orbital_period" text,
  "specific_orbital_energy" text
);
SELECT "altitude_above_the_earth_s_surface" FROM "escape_velocities_at_altitude" WHERE "specific_orbital_energy"='−0.5 mj/kg';