The Apollo missions showed exact science at work. Each part needed to be close to perfection from start to finish. NASA succeeded with 1960s tools—a remarkable feat. Though it was still cutting-edge technology at the time.
More Than Just Landing on the Moon
Most people remember astronauts who walked on the lunar surface, set up the American flag, and moved in low gravity. But NASA faced another challenge to the moon landing—they needed to bring astronauts back to Earth, and safely.
The crew had to rely entirely on their training, spacecraft systems, and precise calculations—there was no room for error. But they were not alone. NASA’s flight controllers on the ground played a critical role and were instrumental in devising the solution that allowed Apollo 13 to survive. The Apollo astronauts had one shot to fire their Lunar Module’s ascent engine and get back to the orbiting command and service module (which was the main spacecraft for lunar missions), or else they’d be stuck there and eventually run out of resources. But NASA, being NASA, had planned for everything. Their scientific and engineering abilities lead many inventions we use day to day.
How Did the Spacecraft Get to the Moon?
Astronauts got to the moon by traveling on a giant rocket (Saturn V) that launched them into space carrying the Command and Service Module (CSM)—their primary spacecraft for the journey. Once in lunar orbit, they transferred to a smaller spacecraft (the Lunar Module) to land on the moon’s surface. For the Apollo missions, it took about 3 days, give or take, to reach the orbit of the Moon.
The guidance computer used in the Apollo moon landings, referred to as the Apollo Guidance Computer (AGC) was one of the first digital computers used in space flight. It was designed to help crew members with navigation of the spacecraft, as well as guidance and control. It has now been turned into a cool calculator watch.
How Did They Get Back Safely?
After completing their mission on the Moon, the Apollo astronauts returned to the Command Module (CM), which was orbiting the Moon while the Lunar Module (LM) was on the surface. Think of it as the “cockpit and living space” of the Apollo spacecraft.
The LM had two parts: a descent stage, which was left behind on the Moon, and an ascent stage, which actually carried the astronauts back into lunar orbit. The LM took off from the Moon and docked with the CM, allowing the crew to transfer back. Once everything was ready, the Service Module (SM) fired its engine to send the spacecraft on a return trajectory to Earth.
The Command Module was the only part of the Apollo spacecraft that returned to Earth after the mission; the Service Module was jettisoned before re-entry and burned up in the atmosphere. It had to enter the atmosphere at a specific angle. Too deep meant destruction; too shallow would also be a problem, since the spacecraft could skip off the atmosphere and be stranded in space. A special heat shield protected the spacecraft against intense temperatures from shock heating and air friction during re-entry. Large parachutes opened when the module slowed down to ensure a soft ocean landing. A team of ships along with helicopters picked up the crew members and brought them to land.
What About Fuel?
People often ask how Apollo astronauts made it to the Moon and back without running out of fuel. The Apollo spacecraft used a staged approach—removing parts of the transportation along the way to reduce weight. Each stage had its own fuel, designed for a specific part of the journey. By discarding empty fuel tanks and modules that were no longer needed, the spacecraft became lighter, requiring less fuel as the mission continued.
However, one interesting thing is that when the astronauts were re-entering Earth’s atmosphere, they had almost used up almost all their fuel. But this was intentional, since NASA planned each action down to its very detail. What ended up happening was that the spacecraft was designed to rely on physics and gravity for the final part of the journey. The Command Module no longer relied on fuel towards the end, since the Earth’s gravity naturally pulled the spacecraft in, and the heat shield protected it during re-entry. After slowing down enough, they had parachutes available to use.
The moon trip posed challenges, and the return created more obstacles. NASA and the Apollo astronauts made history with smart planning, excellent engineering, and an immense amount of bravery. If you are curious about space, here’s how you can track and see the International Space Station (ISS).
