COSMOS DISASTER (1973)
By 1973, the launcher known today as Cosmos-3M was in use in Plesetsk for about six years. According to a post-USSR source, a routine launch was planned for 1:32 a.m. on June 26, 1973s. The preparation, however, run into trouble, when due to a sensor malfunction, the fuel tank was overfilled. The personnel drained part of the fuel and refueled the launcher. Apparently, at this point, the fuel tank developed a leak and 15 seconds before the liftoff, the launch sequence was automatically suspended. The launch was canceled and more than 40-member launch team tried to deactivate the vehicle. At 4:18 and 4:20 a.m. two crews of 13 people were dispatched to the launch pad. At 4:22 a.m. a dual explosion shook the complex, followed by the fire. Seven people were killed at the spot, 13 were injured, two of those later died in the hospital. No announcement about the tragedy was made at the time and its victims were buried in a mass grave in Mirny. A special memorial to the victims of the accident was dedicated in 1974.
VOSTOK DISASTER (1980)
On March 18, 1980, during the fueling of the Vostok-2M launcher with the Tselina satellite, while dozens of military technicians worked on the pad, the devastating explosion incinerated the rocket, killing 50 people. The victims of the tragedy were buried within limits of the town of Mirny, by the same memorial where nine people, who died in a 1973 Cosmos explosion found their final resting place. The official investigation of the cause of the disaster essentially blamed the ground personnel for breaking fire safety rules. However, for years to come the official conclusion was doubted by people familiar with the matter. According to the post-Cold War Russian source, the results of investigation were proved wrong, when on June 23, 1981, a similar disaster was miraculously averted at the last second in Plesetsk. The new investigation pinpointed a valve, made of materials, which on contact with hydrogen peroxide could cause explosive chain reaction. Not until the end of the 1980's an outside world could learn about both accidents.
Unlike many space launch facilities in the World, both Baikonur and Plesetsk are not directly situated on or near a coast. Consequently, the lower, sub-orbital stages of USSR/CIS boosters normally fall back on former Soviet territory. This situation limits the permissible launch azimuths to avoid impacts near populated or foreign regions, e.g., due east launches (the most advantageous) from Baikonur are forbidden since lower rocket stages would fall on Chinese territory. For those launch corridors which are used, tens othousands of tons of spent boosters, many with toxic residual propellants still on board, now litter the countryside. Steps are underway around both Baikonur and Plesetsk to mitigate the situation, but the problem remains monumental.
Baikonur Cosmodrome, Kazakhstan
Before the successful start of Yuryi Gagarin, on October 24, 1960 a big explosion of the rocket took place on one of the grounds. Up to 100 people were found dead.
On June 16-19, 1963 another rocker explosion took place on October, 24 1963. 7 people were found dead.
