Lockheed Martin is the world's largest defense contractor and has dominated the Western market for high-end fighter aircraft since it won the F-35 Joint Strike Fighter program in 2001. Aeronautics is Lockheed's largest segment, which derives upward of two-thirds of its revenue from the F-35. Lockheed's remaining segments are rotary and mission systems, mainly encompassing the Sikorsky helicopter business; missiles and fire control, which creates missiles and missile defense systems; and space systems, which produces satellites and receives equity income from the United Launch Alliance joint venture.