A paper was issued covering 'Results of Studies Made to Determine Required Retrorocket Capability.' The intent of this study was to provide for pilot safety for landing during any emergency condition, as well as at the end of a normal mission.

Two Thiokol retrorockets for the Mercury spacecraft were tested at the Arnold Engineering Development Center engine test facility. The test objectives were to evaluate ignition characteristics.

The first three rocket motors subjected to these tests were successfully tested in a more stringent vibration spectrum than that required for Mercury-Atlas 1 (MA-1), the maximum dynamic reentry and maximum heat on afterbody test flight.

One of the main purposes of this program was the development of a better igniter. The igniter tested was attached to the head end of the propellant grain and coated with a pyrotechnic. Based on three tests it appeared that the delayed ignition problem had been resolved. Thereafter, several other tests were run until the igniter was adjudged to be reliable.

Measures to be taken for hydrogen-peroxide fuel economy for the Mercury spacecraft attitude control system were studied at a coordination meeting. Items considered were orbital attitude, retroattitude hold sequence, and salvo versus ripple retrorocket firing. Astronaut Virgil Grissom reported that the salvo method had already been proven to be unsatisfactory on the Mercury procedures trainer.

Retrofire-from-orbit mission rules were published for the unmanned Mercury-Atlas 4 (MA-4) orbital flight.

Flight and ground tests disclosed that Mercury retrorocket heater blankets were unnecessary to the spacecraft, and this item was removed.

Based on a request from the Manned Spacecraft Center, McDonnell submitted a review of clearances between the Mercury spacecraft 15B retropack and the launch vehicle adapter during separation maneuvers. This review was prompted by the fact that additional batteries and a water tank had been installed on the sides of the retropack. According to the McDonnell study the clearance safety margin was quite adequate.