LT Thor Agena D
LT Thor Agena D - COSPAR 1969-051
AKA: DSV-2L;Long Tank Augmented Thrust Thor;SLV-2H;Thorad Agena D SLV-2H. Status: Retired 1972. First Launch: 1969-06-05. Last Launch: 1972-05-25. Number: 13 . Thrust: 1,571.00 kN (353,174 lbf). Gross mass: 88,731 kg (195,618 lb). Height: 34.00 m (111.00 ft). Diameter: 2.44 m (8.00 ft). Apogee: 1,000 km (600 mi).
OGO 6 was a large observatory instrumented with 26 experiments designed to study the various interrelationships between, and latitudinal distributions of, high-altitude atmospheric parameters during a period of increased solar activity. On June 22, 1969, the spacecraft potential dropped significantly during sunlight operation and remained so during subsequent sunlight operation. This unexplained shift affected seven experiments which made measurements dependent upon knowledge of the spacecraft plasma sheath. During October 1969, a string of solar cells failed, but the only effect of the decreased power was to cause two experiments to change their mode of operation. Also during October 1969, a combination of manual and automatic attitude control was initiated, which extended the control gas lifetime of the attitude control system. In August 1970, tape recorder (TR) no. 1 operation degraded, so all recorded data were subsequently taken with TR no. 2. By September 1970, power and equipment degradation left 14 experiments operating normally, 3 partially, and 9 off. From October 14, 1970, TR no. 2 was used only on Wednesdays (world days) to conserve power and extend TR operation. In June 1971, the number of 'on' experiments decreased from 13 to 7, and on June 28, 1971, the spacecraft was placed in a spin-stabilized mode about the yaw (Z) axis and turned off due to difficulties with spacecraft power. OGO 6 was turned on again from October 10, 1971, through March 1972, for operation of experiment 25 by The Radio Research Laboratory, Japan.
KH-4B. The launch vehicle had a very cold boattail due to a hose discovered to be leaking away warming air to the boattail. The boattail was colder than usual, below freezing. Based on earlier tests of the Thor for just that condition, as relayed by Ed Dierdorf, Thor chief engineer at the time, the temp low was of no concern.
The only problem was that those tests were made with a Thor that carried a Rocketdyne engine lubricated with "lube oil". The Thor being launched used a fuel additive, "Orinite" (like STP "super snot"). The technician that pumped the Orinite into its cannister later stated, "It wasn't for lack of orinite. I put it in just like the procedure said, and I could feel when it was full (with the hand pump). To make sure, I gave it another slug."
That "other slug" cracked the output valve that was only supposed to be cracked by turbopump output pressure. When it cracked the output valve a bit of the "honey" squirted down the tube toward engine bearing jets. This line had a low spot in it by design. The Orinite settled there. When it was chilled by the low temp air at lox loading, the Orinite formed a plug.
Unaware of this chain of circumstances, Launch Director Philip Payne made the decision to launch. The rocket (carrying Agena D and payload) flew for 18 seconds, then wiped out its gears, causing the turbine to overspeed and shed its vanes. These punctured various parts in the boattail like machine gun bullets. With loss of power, the rocket fell not far from the launch pad into Bear Creek canyon.
The final cause was therefore found to be loss of engine lubrication at startup.