The launch escape system

When the spacecraft was sitting on top of the Saturn V, it included one extra element of the Apollo system that everyone hoped would never be used. If it had, it would have been a particularly bad day for all involved. Attached to the tip of the CM was a truss structure upon which was mounted a thin, pencil-like tower which included a

Computer rendering of the LM ascent stage. (Image courtesy of Scott Sullivan.)
Apollo Escape Tower
Diagram of the launch escape system.

powerful solid-fuelled rocket motor. This was the launch escape system (LES). Wrapped around the shiny surface of the command module was a fibreglass and cork shroud, called the boost protective cover (BPC), which shielded the CM from the heat of friction with the air during the first 3 minutes of a nominal ascent, and from the blast of exhaust from the rocket mounted just above, if this were to be used.

If a mishap had occurred with the Saturn V, this motor would have burned for just 8 seconds, but it would have produced a force equivalent to 66 tonnes weight and an acceleration in excess of 7 g that would whip the CM and its crew away from a wayward Saturn. The motor's exhaust exited through four nozzles that were canted to the side to direct its blast away from the spacecraft. If the launch was normal and the launch escape system was not needed, then after the first 3% minutes another smaller rocket motor near the top of the tower pulled away the launch escape system, including the boost protective cover, to fall into the Atlantic Ocean.

SWORDS TO PLOUGHSHARES: VON BRAUN'S ROCKETS

Despite the weight advantages that were gained from the adoption of the lunar orbit rendezvous concept, an Apollo spacecraft and lander were still a huge mass to lift off Earth and send to the Moon, and a very special rocket would be needed for the task.

In every way, the Saturn V epitomised the sheer audacity of the Moon programme. It was big - in size, thrust and weight; it required huge facilities to build, test, transport and launch; and its engines consumed massive quantities of propellant at a prodigious rate. It also demanded fine, subtle control of the enormous forces it produced, and it stretched the will of NASA even to conceive of it. The fact that they did was perhaps because, at the outset, its designers had proposed an even larger vehicle. In comparison, the Saturn V may have seemed relatively straightforward but when the time came to turn ideas to reality, its procurement strained the US aerospace industry every bit as much as the spacecraft it carried.

The lineage of the Saturn V led back to a pre-war German amateur rocketry club, the VfR (Verein fur Raumschiffahrt or Society for Space Travel) where a young Wernher von Braun first shone as a gifted rocket engineer and motivator of men. As Germany armed itself for an assault on Europe, its military, denied conventional long-range artillery by the Versailles treaty, took an interest in the successes of the VfR and how its new rocket technology could be applied to sending warheads towards an enemy.

Von Braun headed a group of engineers based at Peenemunde, a peninsula on the large island of Usedom on Germany's Baltic coast, where his A-4 rocket, fuelled by alcohol and liquid oxygen, was developed. Towards the end of the war, conventional warheads were installed atop the A-4 and the rocket was renamed the V-2 or Vergeltungswaffe 2 (Vengence 2) by the German propaganda ministry. An explosion in Chiswick, London, on 8 September 1944, signalled the first use of the V-2 as a terror weapon. Subsequently, thousands of these rockets, built largely by slave labour under the control of the notorious German secret service (the SS) were launched in the last months of the war in a last-ditch attempt to ruin the morale of the British population.

As the Allied forces marched across Europe in the war's final days, teams of intelligence specialists searched for useful military technology. Von Braun knew that the knowledge and experience of his engineers would be a great prize for whichever Allied power reached them first. The Soviets were closer but he preferred the western option, and arranged for his team to surrender themselves to the American forces. Additionally, he helped his captors to retrieve hardware and documents that would prove useful to them. Though he shamelessly used the military as a means to develop his rocket, von Braun had something else on his mind - space travel.

In 1956, the US Department of Defense made the US Air Force responsible for procuring the country's long-range missiles. Over the succeeding years, the USAF and the companies that worked for it developed the Atlas, Thor and Titan missiles. In the meantime, von Braun's group, still part of the US Army - initially based at the White Sands Proving Ground in New Mexico but now at the Army Ballistic Missile Agency in Huntsville, Alabama - had already devised the Redstone and Jupiter missiles. The former was America's first rocket capable of sending a payload into orbit. After the Soviet Union started the space race by launching Sputnik on 4

October 1957, von Braun's Juno I rocket (a Redstone with solid-fuelled upper stages) countered for America by placing the more scientifically useful Explorer I into high orbit. However, rockets were inextricably tied up with the nuclear weapons they were designed to carry, and since, by now, America could build lightweight nuclear devices, its military rockets tended to be lower powered and less useful as lifting vehicles for spacecraft. Soviet nuclear weapons, on the other hand, were large, heavy affairs, and therefore their rockets had to be relatively powerful, giving them greater capability as space vehicles. Realising this shortcoming, von Braun's team first added solid-fuelled rockets to the top of their Jupiter missile, which was essentially a scaled-up Redstone, to make the Juno II space launcher, then moved onto the development of a heavy-lift booster specifically for space use. Initially designated the Super Jupiter, this booster would cluster first-stage engines and tanks to achieve the desired thrust. This project evolved into the Saturn. As early Saturn development continued into 1960, von Braun's team found themselves transferred to NASA with, at last, a civilian role for their rockets. Their facilities in Huntsville became the Marshall Space Flight Center, with von Braun as its director. Once President Kennedy's lunar goal had been set, the development of the Saturn rockets became part of the civilian space effort, with their final design being firmly linked to the needs of the Apollo spacecraft they would carry.

Though an entire family of launchers were envisaged, only three Saturn rockets came out of the programme. The Saturn I was primarily a development series that proved the concepts of engine clustering in order to achieve high thrust levels as well as testing early Apollo hardware. The Saturn IB used an improved form of the first stage and made use of a new, highly efficient rocket stage, the S-IVB, which was manufactured by the McDonnell Douglas Company. This stage would be crucial to the Apollo programme. It formed the third stage of the Saturn V, in which role it would provide the final impetus to take all NASA's manned spacecraft to the Moon. In the Saturn IB, the S-IVB was a second stage in a man-rated vehicle that could take either a CSM or a LM, but not both, to Earth orbit. The big member of the Saturn family of launchers was the Saturn V, so-called because, in von Braun's mind, there were three paper configurations after the Saturn I that were never built. In truth, as NASA's early plans shifted, there were many configurations that were put on paper to match machines to missions. Many of these used varying quantities of two engines that were being developed, the F-1 and the J-2, but it was the iconic Saturn V, which could lift both the CSM and the LM, that utilised them to fulfil the lunar goal.

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