The initial concept of the use of a tractor rocket for an escape device was suggested by Maxime A. Faget. The idea was developed into the Mercury escape rocket.

A scale model of the Mercury spacecraft (without escape tower), oriented for the reentry phase, was tested at transonic Mach numbers in a 1-foot transonic test tunnel at the Arnold Engineering Development Center, Tullahoma, Tennessee.

An abort test was conducted at Wallops Island on a full-scale model of the spacecraft with the escape tower, using a Recruit escape rocket. The configuration did not perform as expected (erratic motion), and as a result, the Langley Research Center was requested to test small-scale flight models of the abort system to determine its motion in flight.

Langley's Pilotless Aircraft Research Division conducted, at Wallops Island, the first full-scale test simulating a pad-abort situation. A full weight and size spacecraft was used. For the first 50 feet the flight was essentially straight, indicating the successful functioning of the abort rocket. Thereafter, the spacecraft pitched through several turns and impacted a short distance from the shore. The malfunction was traced to the loss of a graphite insert from one of the three abort rocket nozzles, which caused a misalignment of thrust.

Space Task Group officials were involved in an investigation as to whether the escape system should be changed. In the original proposal, McDonnell's plan was to use eight small rockets housed in a fin adapter, but this plan was set aside for a NASA developed plan in which a single-motor tripod would be used. Later, during a test of the escape system, the escape rockets appeared to fire properly but the spacecraft began to tumble after launch. This tumbling action caused concern, and Space Task Group engineers felt that the tower-escape system might have to be discarded, and a 'second look' was taken at the McDonnell proposal. The engineers concluded, however, that there were too many problems involved and the single-motor tripod concept was retained and has been proven to be quite effective.

Range Safety personnel at the Atlantic Missile Range were briefed by Space Task Group personnel on the description of the Mercury spacecraft, how it would function during a normal flight on an Atlas launch vehicle, and suggest methods for initiation of an abort during different powered phases of a flight. Atlantic Missile Range personnel discussed their past experience, and work was started to draft a Project Mercury range safety plan.

Investigations of two escape configurations for Mercury spacecraft were conducted in a 16-foot transonic circuit at the Arnold Engineering Development Center, Tullahoma, Tennessee, for determination of static stability and drag characteristics of the configurations.

Escape-motor canting-angle tests were completed at Wallops Island. Tests were conducted in 5 degree increments between 10 degrees to 30 degrees, and visually it appeared stability was better at the larger angle.

In a meeting at Langley, NASA officials concluded that the tower configuration was the best escape system for the Mercury spacecraft and development would proceed using this concept. However, limited studies of alternate configurations would continue.

A successful pad abort flight of a Mercury boilerplate spacecraft with a production version of the escape tower and rocket was made. The escape rocket motor was manufactured by Grand Central Rocket, and the flight was the first operational test of this component.

A boilerplate spacecraft, instrumented to measure sound pressure level and vibration, was launched in the second beach abort test leading to the Little Joe test series. The purpose of the instrumentation was to obtain measurement of the vibration and sound environment encountered on the capsule during the firing of the Grand Central abort rocket. Memo, Charles A. Hardesty to NASA Langley IRD files, subject: Sound Measurements on the Second Beach Abort Test on the Little Joe Capsule, Oct. 9, 1959.

A meeting of Space Task Group, Wallops Station, and McDonnell personnel was held to review and evaluate Mercury escape-system qualification-test results. In the continuing efforts of this activity, the responsibility in attaining test objectives was apportioned among the three organizations.

The Arnold Engineering Development Center tested the Grand Central solid-fuel rocket motor used to propel the Mercury spacecraft escape system.The purpose of the test was to verify altitude ignition and to determine the combustion-chamber-pressure-time curve.

These tests were completed at the end of July 1960. As a part of the qualification program, three escape-rocket motors were successfully fired on a spacecraft model at conditions corresponding to approximately 100,000 feet altitude in the Lewis Research Center altitude wind tunnel. One motor was tested on a four-component balance system to determine thrust misalignment of the rocket motor. According to test results, the rocket motor appeared to meet operational requirements.

McDonnell's first production spacecraft, with its escape rocket serving as the propulsion force, was launched from Wallops Island. Designated the beach-abort test, the objectives were a performance evaluation of the escape system, the parachute and landing system, and recovery operations in an off-the-pad abort situation. The test was successful.

The first production Mercury spacecraft, used in the beach-abort test, was returned to the McDonnell plant for an integrity test.

LJ-5, the first of the series with a McDonnell production spacecraft, was launched from Wallops Island to check the spacecraft in an abort simulating the most severe launch conditions. The launch was normal until 15.4 seconds after lift-off, at which time the escape rocket motor was prematurely ignited. The spacecraft did not detach from the launch vehicle until impact and was destroyed. Failure to attain mission objectives was attributed to several possible causes. One of these was failure of the spacecraft-to-adpater clamp-ring limit switches. Another possibility was failure of the escape tower clamp-ring limit switches. And the third was improper rigging of the limit switches in either of those locations so that vibration or deflection could have caused switch closure. Since the test objectives were not met, a repeat of the mission was planned.

This unmanned mission was unsuccessful because premature cut-off of the launch vehicle engines activated the emergency escape system when the vehicle was only about 1 inch off the pad. Engine cut-off was caused by premature loss of electrical ground power to the booster. The launch vehicle settled back on the pad with only slight damage. Since the spacecraft received a cut-off signal, the escape tower and recovery sequence was initiated. The undamaged spacecraft was recovered for reuse.

Mercury spacecraft No. 14 was delivered to Wallops Island for the Little Joe 5A (LJ-5A) maximum dynamic pressure abort test.

As of this date, the Space Task Group, Convair-Astronautics, Space Technology Laboratories, McDonnell, and the Marshall Space Flight Center had completed a number of extensive studies on the subject of the safe separation of the Mercury spacecraft from the launch vehicle during an emergency. The following papers include a report of these studies: NASA Project Mercury Working Paper No. 111, 'Mercury-Redstone Separation Distance ...'; NASA Project Mercury Working Paper No. 141, 'Dispersion Study of Separation Distance ...for Mercury-Redstone'; and NASA Working Paper No. 152, 'Determination of Mercury Escape Rocket Thrust Eccentricity ...from Mercury-Atlas Booster.'

It would be used for the Little Joe 5B (LJ-5B) maximum dynamic-pressure abort mission. This spacecraft was first used in the Little Joe 5A (LJ-5A) mission and was then refitted for the LJ-5B flight.