The Martin X-23 PRIME (Precision Recovery Including Maneuvering Entry) was a small uncrewed lifting body re-entry vehicle tested by the United States Air Force in the late 1960s. PRIME 1 was launched on 21 December 1966 on a mission to simulate a low-earth orbit reentry with a zero cross-range. The ballute deployed at 30.43 km, though the recovery parachute failed to completely deploy. The vehicle crashed into the Pacific Ocean and was not recovered.