This failure mode had never occurred in the 240 Atlas launches prior to AC-5 despite always having been possible. Until a more permanent solution could be found, a temporary fix was made for Atlas-Agena vehicles by equipping the valve with a manual lock that would be enabled during the pre-launch countdown. In addition, an unrelated system malfunction in AC-5 was discovered when an examination of telemetry data found that a power failure had occurred in the guidance computer. As a temporary fix for Atlas-Centaur AC-6, 7, and 8, several unused components were removed from the computer in order to reduce system complexity and failure points. The failure of AC-5 resulted in another Congressional investigation, again headed by Rep. Joseph Karth, who argued that $600 million of taxpayer money had been spent on Centaur so far with little to show for it and that Convair was taking advantage of being the sole supplier of the Atlas-Centaur vehicle. The committee proposed that NASA consider alternate choices for the planetary probe program, such as Titan IIIC, or outsource the manufacture of Centaur to other contractors. However, NASA representatives argued that this was impossible as no other aerospace company had the experience or technical capability to manufacture the Centaur's balloon tanks. The pad LC-36B was hastily brought online, with an entirely successful AC-6 launched on 11 August 1965. Although Centaur appeared flight-ready, the Surveyor program was delayed. Vehicles AC-7 and AC-10 were designated for the first Surveyor missions, with AC-8 to carry out one more test, which took place on 7 April 1966 at 08:01 GMT with a payload of 784,7 kg. The Centaur's ullage motors failed again because they did not have enough propellant for the mission. It decays the 5 May 1966. Seven Surveyor probes were launched, all on Atlas-Centaur. Beginning with AC-13 (Surveyor 5), Atlas-Centaur vehicles switched to the standardized SLV-3 Atlas core. Initially, a modified Atlas D designated LV-3C was used as the first stage This was quickly replaced by SLV-3C, and later the SLV-3D, both derived from the standard Atlas SLV-3 rocket. Two spaceflights, with the Pioneer 10 and Pioneer 11 space probes to Jupiter, Saturn and exiting the Solar System, used a spin-stabilized "Star-37E" solid propellant final stage weighing 2473 pounds and contributing 8000 mph to the velocities of the spacecraft.