Mercury Atlas 9 (MA-9, designated also Faith 7) was the fourth and final manned orbital flight of the Mercury program. The pilot was L. Gordon Cooper, Jr. The objectives of MA-9 were to: (1) evaluate the effects on the astronaut of approximately one day in orbital flight; (2) verify that man can function for an extended period in space as a primary operating system of the spacecraft; and, (3) evaluate in a manned one-day mission the combined performance of the astronaut and a Mercury spacecraft specifically modified for the mission. Originally scheduled for launch in April, the mission was delayed twice. The first delay (February) was due to a decision to rewire the Mercury-Atlas flight control system. The second (May 14) occurred on the scheduled day of launch when a problem developed with the fuel pump in the diesel engine used to retract the gantry from the launch vehicle. This resulted in a delay of roughly 129 minutes after countdown had already reached T-60 minutes. Subsequent to the repairs on the gantry engine, however, a separate problem, the failure of a computer converter at the Bermuda tracking station, forced the cancellation of the launch at T-13 minutes. The launch was rescheduled for the following day (May 15). The countdown then proceeded without a hitch until T-11 minutes and 30 seconds when a problem developed in the guidance equipment and a brief hold was called until it was resolved. Another hold was called at the T-19 second mark to ascertain whether the systems had gone into automatic sequencing as planned. The liftoff ended up being excellent, however, with flight sequencing (booster engine cut-off, escape tower jettison, sustainer engine cut-off) operating perfectly and the spacecraft being inserted into orbit at a velocity described as being "almost unbelievably correct". A number of alterations were made to the MA-9 spacecraft, most of them due to the extended duration of the flight. Among these were the increased capacity of several life support system components (additional oxygen and water, increased urine and condensate capacity, etc.), a larger capacity fuel tank, and larger capacity batteries (two 3,000 W-hour vs. two 1,500 W-hour). Deleted from the flight, due to weight considerations, were several backup or other components deemed unnecessary. These included the periscope, the backup UHF voice transmitter, the rate control system, and the backup telemetry transmitter. Also installed was a slow-scan television unit for in-flight evaluation in monitoring the astronaut and instruments. A number of improvements were also made to the pressure suit worn by Cooper. These included a mechanical seal for the helmet, new gloves with an improved inner liner and link netting between the inner and outer fabrics at the wrist, and a torso section redesigned for increased mobility. The boots were also now integrated with the suit to provide increased comfort for the longer mission, to reduce weight, and to decrease the time required to don the suit. Another change moved the life vest from the center of the chest to a pocket on the lower left leg, thus reducing the bulkiness from the suit and, again, providing more comfort during the flight. A number of in-flight experiments were planned for and carried out during the MA-9 flight. They included two visual acquisition and perception studies, several photographic studies, two radiation packages, a tethered balloon experiment, a study of the behavior of fluids in zero gravity, and a micrometeorite study. A flashing beacon was deployed on the third orbit and Cooper reported that he was able to see it on the night side of the fourth orbit. Attempts were made to deploy the balloon, both of which failed. On the seventeenth orbit Cooper photographed the zodiacal light. Cooper also became the first to sleep in orbit. In addition to a planned rest period beginning the tenth orbit, he also drifted off to sleep during the second orbit for a short period. (In fact, Cooper had also reported taking a short nap during the countdown phase.) During the planned sleep period Cooper's suit temperature rose and he roused, reset the temperature control, and resumed his rest. The first malfunction of concern on MA-9 occurred during the nineteenth orbit when the 0.05g light came on. The light, sensitive to changes in gravity, normally lit during reentry. The pilot proceeded to check out the necessary attitude information and all telemetry indicated the spacecraft was in the correct orbit. It was therefore concluded that the light was erroneous. However, because of this, it was determined that the potential existed that not all of the automatic system for reentry would function. The pilot was advised to use the manual mode for reentry, becoming the first astronaut to use this method exclusively. During the flight, the spacecraft attained a maximum velocity of 28,075 km/hour and an altitude of 265 km. The capsule reentered under the manual control of the pilot after completing 22 orbits, landing about 130 km southeast of Midway Island in the Pacific Ocean, about 6.4 km from the prime recovery ship, USS Kearsarge. The duration of the flight was 34 hours 19 minutes and 49 seconds during which Cooper travelled nearly 875,000 km.