On August 8, 1957, the Re-Entry Test Vehicle Project of the Army Ballistic Missile Agency achieved a successful atmospheric re-entry of its Orbiter stack. The International Geophysical Year, declared on July 1, 1957, included a competition for the first successful satellite launch in its Race to Space agenda. American scientists hoped to work collaboratively with the U.S. military to develop new technology for rockets with space exploration and research benefits, as well as military and strategic roles. The challenge facing rocket development programs included not only how to design engines capable of freeing a large, heavy object from the clutches of earth’s gravity, but also how to enable a portion of that heavy object to return to earth without burning up as it passed back through our atmosphere.
The Army’s Re-Entry Test Vehicle Project, started in 1955, progressed in stages. The Army Ballistic Missile program’s overall goal: develop an intercontinental ballistic missile (ICBM) capable of accurately delivering a nuclear warhead, with all necessary tracking and control systems technology. From the start, researchers knew that nuclear warheads would need to be protected from the intense heat generated while re-entering the earth’s atmosphere. Theoretical studies and laboratory tests pointed to the use of glass-fiber-based materials for use in warhead shields. The glass-fiber shields – also referred to as “ablative technology” – would protect the payloads by gradually burning away during re-entry. The re-entry project designed rocket telemetry (tracking) systems, a nose cone assembly to hold the glass shields which would float on water, enabling recovery and analysis, and the ablative technology. The Orbiter stack, or rocket, had already been developed as part of the Redstone and Sergeant missile programs and consisted of four stages of rocket motors and boosters.
The first test flight , held September 20, 1956, demonstrated that the vehicle design and tracking systems were fully functional. The second flight, May 15, 1957, was the first to include the ablative technology. The tracking information indicated to the researchers that the heat shields had worked, but because of a guidance system failure, they were unable to recover the nose cone post-splashdown for confirmation. They needed to know how much of the glass material had eroded, in order to make an efficient warhead design.
The final test, on August 8, 1957, was the success they were hoping for. The rescue and salvage ship USS Escape recovered the nose cone and analysis of the heat shield showed that only a small amount of material had burned away, confirming an effective design. The United States was one step closer to an arsenal of nuclear ICBMs to train on the USSR.
Image Credits: U.S. Army; NASA