The Martin B-57 Canberra was a United States-built, twin jet engine light bomber and reconnaissance aircraft, which entered service with the United States Air Force (USAF) in 1953. The B-57 was initially a version of the English Electric Canberra built under license. However, the Glenn L. Martin Company significantly modified the design and produced several unique variants.
A few are still in use by NASA Johnson Space Center in Houston, TX as high altitude scientific research aircraft.
At the outbreak of the Korean War in 1950, the USAF found itself in dire need of an all-weather interdiction aircraft. The piston-engined Douglas A-26 Invaders were limited to daytime and fair weather operations and were in short supply. Thus, on September 16, 1950 the USAF issued a request for a jet-powered bomber with a top speed of 630 mph (1,020 km/h), ceiling of 40,000 feet (12,190 m), and range of 1,150 miles (1,850 km). Full all-weather capability and secondary reconnaissance role had to be included in the design. To expedite the process, only projects based on existing aircraft were considered. The contenders included the Martin XB-51, and the North American B-45 Tornado and AJ Savage.
Foreign aircraft including the Canadian Avro Canada CF-100 Canuck and the new Canberra — which had not officially entered service with the Royal Air Force (RAF) at the time — were also considered, an extremely rare move. The AJ and B-45 were quickly dismissed because their outdated designs had limited growth potential. The CF-100, an all-weather interceptor, was too small and lacked sufficient range. The XB-51, while very promising and much faster, had limited maneuverability, a small weapons bay, and limited range and endurance.