MID-AIR RETRIEVAL SYSTEM
Mid-air retrieval is a technique used in atmospheric reentry when the reentering vehicle is incapable of a satisfactory unassisted landing. The vehicle is slowed by means of parachutes, and then a specially-equipped aircraft matches the vehicle's trajectory and catches it in mid-air.
This is a risky technique, and so is only used when other forms of landing are infeasible. Successful mid-air retrieval requires correct operation of the retrieving aircraft, favorable atmospheric conditions, and successful execution of a tricky maneuver, in addition to correct operation of the vehicle itself. Helicopters are the optimal aircraft for these operations due to their maneuverability. The need for human aviators to perform a maneuver which would normally be classed as a stunt may in the future be avoided by advances in unmanned aerial vehicles.
The first successful mission use of mid-air recovery was on 19 August 1960 when a C-119 recovered film from the Corona mission code-named Discoverer 14. This was the first successful recovery of film from an orbiting satellite and the first aerial recovery of an object returning from Earth orbit.
The early-1960s era Corona reconnaissance satellite returned delicate film capsules to Earth that required mid-air retrieval by a JC-130 Hercules & HC-130 airlifter.
Also during the early 1960s, several losses of U-2 reconnaissance planes over the USSR, China and Cuba forced Americans to find the ways of learning more about Soviet S-172/SA-2 SAM systems. The development of unmanned drones became the wave of the future in being able to gather intelligence information without putting manned aircraft in jeopardy.
All American Engineering Co. (AAE) and Sikorsky Aircraft had demonstrated the feasibility of using helicopters for midair recovery in 1959. An H-43 from Holloman AFB, NM was fitted with a system designed to perform midair recovery of test packages and in 1961 made the first ever midair recovery of a parachute-borne object by a U.S. Air Force helicopter. (http://rotorheadsrus.us/documents/524.html)
The success of this project led eventually to the USAF CH-3 Mid-Air Recovery Systems (MARS) that performed hundreds of midair recoveries of reconnaissance remotely piloted vehicles during the Vietnam War. Photo reconnaissance drones used USAF C-130s as launch vehicles and CH-3 and CH-53 helicopters as recovery vehicles.
Various units were involved in the MARS operations in testing vehicles and recovery.
The 6593rd Test Squadron (6594th Test Group) began in 1958 in Hawaii,
The 350th Strategic Recon Sqdn operated from Danang, SVN from 1967 – 68,
The 6514th Test Squadron at Hill AFB, UT 1971,
The 432nd Tactical Drone Group, Davis-Monthan AFB in 1976.
With the advent of unmanned drones such as the Predator which are able to takeoff and land on runways, they have negated the need of helicopters for retrieval.