Vanguard SLV-6

Vanguard SLV-6 was a United States satellite launch attempt conducted as part of the Project Vanguard program. Launched on 22 June 1959 from Cape Canaveral Air Force Station, the mission aimed to place the Vanguard 3 satellite into Earth orbit to study the Van Allen radiation belt and Solar X-rays. The flight ended in failure approximately 20 seconds after liftoff when the Vanguard rocket's first stage suffered a catastrophic loss of thrust, leading to its destruction by the Range Safety Officer.

Overview

The mission was the sixth in the series of Satellite Launch Vehicle (SLV) flights under the Naval Research Laboratory's Project Vanguard, a program initiated in response to the Cold War space race. Following the earlier successes of Vanguard 1 and Vanguard 2, the United States Navy sought to continue its scientific exploration of near-Earth space. The primary objective was to deploy a sophisticated scientific observatory, continuing the work of prior missions like Explorer 1 and Sputnik 3. The launch occurred during a period of intense competition with the Soviet Union, which had achieved milestones with Sputnik 1 and Luna 1.

Mission and launch

Liftoff of Vanguard SLV-6 occurred at 20:30 UTC on 22 June 1959 from Launch Complex 18A at Cape Canaveral Air Force Station. The three-stage launch vehicle performed nominally for the initial moments of flight. However, at approximately T+20 seconds, engineers monitoring telemetry data observed a sudden and severe drop in chamber pressure within the General Electric X-405 engine powering the first stage. This resulted in an immediate and complete loss of propulsive force. The Range Safety Officer at the Eastern Test Range subsequently issued the destruct command, causing the vehicle to explode over the Atlantic Ocean. The failure was attributed to a rupture in the engine's combustion chamber.

Design and specifications

The launch vehicle was a standard Vanguard rocket, a design derived from the Viking research rocket. Its first stage was powered by the General Electric X-405 engine, burning RP-1 kerosene and liquid oxygen. The second stage utilized an Aerojet AJ10-118 engine fueled by inhibited red fuming nitric acid and unsymmetrical dimethylhydrazine, while the third stage was a solid-propellant Allegany Ballistics Laboratory X-248 motor. The payload, designated Vanguard 3, was a 23-kilogram satellite equipped with instruments to measure cosmic rays, micrometeoroid impacts, and solar X-ray emissions. Its design was similar to the successful Vanguard 2 satellite built by the Naval Research Laboratory.

Legacy and significance

Despite its failure, Vanguard SLV-6 contributed valuable failure analysis data that informed subsequent American launch vehicle programs, including the Thor and Atlas families. The investigation into the X-405 engine flaw led to manufacturing improvements that benefited other projects. Scientifically, the mission's objectives were later fulfilled by the successful Vanguard 3 launch in September 1959 and other satellites like Explorer 7. The Vanguard program as a whole, despite early setbacks, proved the reliability of its satellite designs, with Vanguard 1 remaining the oldest human-made object in Earth orbit. The program's technological legacy fed directly into the development of later NASA programs during the Space Race.

Category:Project Vanguard Category:Spacecraft launched in 1959 Category:Satellite launch failures