The Apollo 11 mission, which took place in 1969, marked the first time humans walked on the Moon. However, getting there was only half the battle; the astronauts also had to return safely to Earth.
The Apollo Earth Landing System (ELS), which relied on a series of parachutes, played a critical role in ensuring a successful return.
In this blog post, we will delve into the technical aspects of the Apollo 11 mission parachute, from its development to its deployment and its role in the safe return of the astronauts.
The Apollo 11 mission relied on three main parachutes to land the command module on Earth safely.
Made by Northrop Ventura, the parachutes were constructed of a combination of synthetic fabric, aluminum, nylon, steel, plastic, and brass.
During landing, the main parachutes opened at 10,000 feet, slowing the rate of descent from 175 mph to 22 mph, ensuring a safe splashdown.
Overview of Apollo 11’s Parachute System
During the Apollo 11 mission, three main parachutes were deployed for the Earth landing of the command module.
The parachutes were activated by pilot parachutes at 10,000 feet and reduced the module’s descent speed from 175 mph to 22 mph.
If one parachute failed (as happened during the Apollo 15 mission), the remaining two were capable of slowing the module to 25 mph.
The parachutes were designed to hold the module at a 27.5-degree angle so that the slanted corner would make contact with the water first, minimizing impact forces.
After the splashdown, the main parachute risers were cut, and the parachutes were released.
The main “ringsail” parachutes were manufactured by Northrop Ventura and had dimensions of approximately 40.64 x 873.76 x 345.44cm (1ft 4in x 28ft 8in x 11ft 4in).
The material used in their construction included Synthetic Fabric, Aluminum, Nylon, Steel, Plastic, and Brass.”
Designing the Apollo 11 Parachutes: A Development Journey
The development of the Apollo 11 mission parachute began in January 1962, when NASA released the first specifications for the system.
The goal was to design and manufacture parachutes capable of landing the Apollo Command Module (CM) on the water at approximately 20 miles per hour.
The most significant challenge faced by engineers during the development process was the constant increase in the weight of the CM, which grew from 8,150 pounds in 1962 to 13,000 pounds in 1968.
To handle the additional aerodynamic stresses, the parachute system had to be redesigned following changes to the Apollo CM after a fire in 1967.
Ensuring Safety: Testing the Apollo 11 Parachutes
To test and qualify the Apollo ELS for human space flight, contractor Northrop Ventura conducted drop tests at the Joint Parachute Test Facility in El Centro, California.
The first parachute test of an Apollo boilerplate CM from a modified Air Force C-133 took place on May 3, 1963, and was successful.
Over the next five years, the contractor completed 13 developmental and 21 qualification drop tests using boilerplate capsules, in addition to multiple drop tests using lower-fidelity mockups and wind tunnel and laboratory tests.
With the successful completion of the final qualification drop test on July 3, 1968, NASA declared the ELS safe for human missions, and the system was used for the Apollo 7 mission later that year.
Sequence of Deployment: Apollo 11 Parachutes in Action
The Apollo ELS consisted of nine parachutes deployed in a complex sequence: three main parachutes, three pilot parachutes, two drogue parachutes, and one forward heat shield separation parachute.
During a normal reentry, the sequence began with the jettison of the forward heat shield, aided by the deployment of a 7-foot parachute.
Two 16.5-foot drogue parachutes opened 1.6 seconds later to provide initial deceleration and stabilization and remained attached to the CM until about 11,000 feet altitude.
At drogue disconnect, three 7-foot pilot parachutes deployed, providing sufficient force to extract the main parachute packs, opening the three 83.5-foot main parachutes, which inflated to their fully open condition through a two-step reefing process.
In-depth Look: Technical Features of Apollo 11’s Main Parachutes
The three main parachutes, each 83.5 feet across, were made of fabric strong enough to slow the descent of the capsule from 160 m.p.h. to a safe landing speed.
The fabric covered 7,200 square feet, and each square yard weighed just one ounce. The parachutes were assembled from panels of material sewn together with 3.5 miles of thread and 2 million individual stitches using black Singer sewing machines.
The main parachutes, manufactured by Northrop Ventura, were folded and packed by hand by only three trained and licensed individuals: Norma Cretal, Buzz Corey, and Jimmy Calunga. These parachutes held the Command Module at a 27.5-degree angle so that the module’s slanted corner would penetrate the water first, reducing the impact force.
The final deployment of the main parachutes
The final deployment of the main parachutes completed the ELS landing sequence, bringing the CM to a splashdown speed of approximately 20 miles per hour.
The ring-slot design of the main parachutes allowed for high stability and control during the descent, and the 83.5-foot diameter offered an acceptable trade-off between landing speed and splashdown area for a wide range of CM landing points.
The reliability of the ELS was essential to the success of the Apollo missions, as the parachutes were the only means of returning astronauts from the Moon back to Earth.
Given this critical role, the ELS underwent extensive testing and analysis to ensure its reliability and performance under a wide range of conditions.
Testing was performed using both full-scale and subscale models, and various load conditions were tested to ensure the integrity of the parachutes under the most extreme conditions.
The testing also confirmed the stability of the ELS during descent, providing a safe landing environment for the astronauts.
Apollo 11 was the first mission to land astronauts on the Moon successfully and return them safely to Earth. On July 20, 1969, Neil Armstrong and Buzz Aldrin became the first human beings to walk on the Moon, and the successful landing and return were made possible, in part, by the reliable and well-designed Apollo ELS.
The Apollo 11 mission was a historic achievement for humanity and a testament to the power of human ingenuity and engineering. The development and successful deployment of the Apollo ELS was a critical component of the Apollo missions and helped ensure the safe return of the astronauts from the Moon.
The parachute system remains a remarkable example of the ingenuity and expertise of engineers and technicians and a reminder of the challenges that can be overcome with hard work and determination.
The Apollo 11 mission will always be remembered as a turning point in human history, and the Apollo ELS will always be remembered as an integral part of that achievement.
The legacy of the Apollo missions continues to inspire future generations of engineers and scientists, and the Apollo ELS serves as a model for designing and deploying advanced landing systems for human spaceflight.
For a deep dive into the fascinating details of NASA’s historic lunar missions, including technological breakthroughs and mission milestones, explore our comprehensive Complete Guide to the Apollo Program.