Voyager, Viking and Helios: What’s common in these 3 space probes?
All of them were launched by Titan IIIE rocket. An American expendable launch system, Titan IIIE was launched 7 times between 1974 and 1977. It enabled several high-profile NASA missions, including the Voyager and Viking planetary probes and the joint West Germany-U.S. Helios spacecraft.
Titan IIIE resulted from the need of a powerful rocket at reduced funding scenario of 1960s. NASA came up with the plan of modifying the Centaur upper stage (a different rocket family) with Titan III. The end result: Titan IIIE more than tripled the payload capacity of Atlas-Centaur, and incorporated improved thermal insulation, allowing an orbital lifespan of up to five hours, an increase over the 30 minutes of the Atlas-Centaur. This is the reason Titan IIIE is also known as Titan III-Centaur.
First Launch Failure and its reason
The first launch of the Titan IIIE on February 11, 1974, was a failure. The Centaur’s LOX boost pump did not activate, preventing proper mainstage engine operation from being achieved. To reduce the chance of a second failure, prelaunch procedures were implemented to verify that Centaur’s pumps were free and unobstructed.
Nearly four years passed before the cause of the failure was determined: an improperly installed mounting bracket inside the liquid oxygen (LOX) tank. This bracket held a LOX regulator in place. The technician responsible for installing it had found that the normal tool used to screw bolts into place was too short to reach the bracket. He thus used a slightly longer socket wrench that gave him more reach. Before the technician retired, he failed to inform his successor about this. When the new technician attempted to attach the bolt with the wrench specified in the assembly instructions, the wrench was too short and prevented him from screwing it into place properly. The bolt came loose, fell off, and got sucked into one of the LOX boost pumps, which jammed the pump and prevented its operation.
The next flight of the Titan IIIE was on December 10, 1974, carrying the Helios-A spacecraft. This mission was successful, as were all subsequent launches including the ones carrying the Voyager and Viking spacecrafts. The Voyager 1 probe was launched on September 5, 1977, from Launch Complex 41 at the Cape Canaveral Air Force Station, aboard a Titan IIIE launch vehicle. The Voyager 2 probe had been launched two weeks earlier, on August 20, 1977.
Titan IIIE launch video [Voyager 2], Video credits: Retro Source HD