Mercury-Atlas 4 was an uncrewed spaceflight of the Mercury program. It was launched on September 13, 1961, at 14:09 UTC from Launch Complex 14 at Cape Canaveral, Florida. A Crewman Simulator instrument package was aboard. The craft orbited the Earth once. There were a series of delays getting the Atlas and Mercury capsule ready as the postflight findings from MA-3 had necessitated extensive modifications to the booster. Vehicle 88D did not undergo its factory rollout inspection until June 30 and delivery to Cape Canaveral waited until July 15. Moreover, the flight was not going to use Mercury capsule #9 as planned, but instead capsule #8, which had been recovered from the MA3 launch and refurbished. Capsule #8 was also the last of the older models with small port windows, no landing bag, and a heavy locking mechanism on the hatch. A series of delays occurred due to problems with the Atlas autopilot, including the replacement of a defective yaw rate gyro. Launch was originally intended for August 22 but pushed back. Further delays happened when it was discovered that the brand of transistor used in both the Atlas and Mercury were prone to forming solder balls, thus the entire last week of August was spent laboriously repairing them. In August, the Soviet Union orbited cosmonaut Gherman Titov in Vostok 2 for a daylong flight, producing stunned disbelief in the US and paranoia in some quarters as Soviet premier Nikita Khrushchev proclaimed in a speech afterwards "We have launched Gagarin and Titov into space, and we can deliver a nuclear weapon to any point on the planet!" This flight was an orbital test of the Mercury Tracking Network and the first successful orbital flight test of the Mercury program--all previous successful launches were suborbital. The payload consisted of a pilot simulator (to test the environmental controls), two voice tapes (to check the tracking network), a life support system, three cameras, and instrumentation to monitor levels of noise, vibration and radiation. Because it was suspected that a transient voltage caused the malfunction of MA3's programmer (and that a similar problem had been responsible for Big Joe's failure to stage), Convair equipped the autopilot to give the engines a counteracting capability. Thus, testing this was also an objective of the flight. Also, the Atlas vehicle used to launch MIDAS 3 in July had experienced a programmer reset at staging, which did not have