Fifty years ago, NASA successfully completed a national goal set by President John F. Kennedy for America to become first nation in the world to land astronauts on the Moon, and most importantly, return them safely back to Earth. CCS had the immense honor of participating in the historical event.
Apollo 11 embarked on its mission on July 16th, 1969 carrying Commander Neil Armstrong, Command Module Pilot Michael Collins, and Lunar Module Pilot Edwin “Buzz” Aldrin on board.
On July 20th, Apollo 11’s Lunar Module became the first spacecraft in history to achieve a landing on the Moon, making Armstrong and Aldrin the first men to ever walk on it.
The capsule began its journey back to Earth on July 22nd along with a CCS barometric pressure switch aboard. As it entered the upper atmosphere at a re-entry speed over 17,000 miles per hour, it had to slow down to roughly 124 miles/hour to prepare for landing. The pressure switch had a critical job: ensure the initiation of the earth landing sequence and chute deployment went smoothly and at the correct altitude.
At approximately four and a half miles above the earth, the timely and vital automatic start of this sequence began. The sequence included jettison of the protective nose cover of the capsule, deployment of the drogue chutes, the subsequent release of the drogue chutes and then deployment of the main parachutes. The three main chutes then opened permitting the capsule to make a safely controlled splash-down in the Pacific Ocean at the speed of about 22 miles per hour at 12:50 p.m. on July 24th.
Why did NASA and North American Aviation, the builder of the Apollo spacecraft capsule, select the CCS pressure switch for one of the most critical elements in the Apollo earth landing sub-system?
First and foremost, they needed:
- A reliable pressure switch that at the critical time and altitude, would function flawlessly
- Rugged technology that could withstand the heavy vibration of the launch and re-entry (The switches were subjected to 20 G acceleration, and 78 G shock & vibration testing along 3-axis)
- Switches that required low or no power consumption
- Impervious to temperatures and humidity considering the environmental conditions from launch through space and back into the atmosphere (The switches for the Apollo spacecraft were tested within a temperature range of -65 oF and 160 oF, that is -53 oC and 71 oC)
- Technology that minimized the concern for contact bounce and contact chatter from vibration as the switch approached closure
Although the CCS pressure switch had proven its performance prior to the Apollo program during the Mercury and Gemini programs and Saturn flights, Apollo 11 was undoubtedly a highlight to its many successes. The switch technology and elements found in the 24,000-foot barometric pressure switch of the Apollo command module are the same found today in CCS pressure switches used throughout aerospace and industrial markets.