The picture below shows the Apollo spacecraft that took astronauts to the Moon in 1969. The spacecraft weighed 6.1 million pounds, and its motors produced 7.5 million pounds of thrust. Explain how the spacecraft left the surface of the earth.
The Apollo spacecraft used a multi-stage launch system to leave the surface of the Earth. Here's how it worked:
1. First Stage (S-IC): The Apollo spacecraft was placed on top of a Saturn V rocket, which had three stages. The first stage, known as the S-IC (Saturn-First Stage), was responsible for the initial thrust to lift the entire spacecraft off the surface. The S-IC stage contained several rocket engines powered by liquid oxygen and refined kerosene called RP-1. These engines collectively produced approximately 7.5 million pounds of thrust.
2. Lift-off: As the engines of the S-IC stage ignited, the immense thrust generated caused the Saturn V rocket and the Apollo spacecraft to lift off the launchpad. The goal was to overcome Earth's gravity, enabling the spacecraft to start its journey towards the Moon.
3. First Stage Separation: Once the first stage burned out its fuel, it was jettisoned to reduce weight. This separation was necessary to optimize the subsequent stages' performance. The spent S-IC stage fell back to Earth's atmosphere and either burned up or fell into the ocean.
4. Second Stage (S-II): With the first stage separated, the second stage, known as the S-II, ignited. The S-II used five rocket engines powered by liquid hydrogen and liquid oxygen. It provided additional thrust to propel the spacecraft further into space.
5. Second Stage Separation: Once the second stage completed its burn, it was detached from the spacecraft. The spent S-II stage also either burned up in the atmosphere or fell into the ocean.
6. Third Stage (S-IVB): The third stage, known as the S-IVB, took over from the second stage. It had a single rocket engine powered by liquid hydrogen and liquid oxygen. This stage provided the necessary velocity to escape Earth's gravitational pull and enter a trajectory towards the Moon.
7. Translunar Injection: The S-IVB stage burned until it reached a specific velocity, known as translunar injection (TLI). At this point, the spacecraft was on a trajectory that would take it to the Moon.
8. Third Stage Separation: Once the TLI burn was complete, the S-IVB stage was jettisoned. Unlike the previous stages, the S-IVB was not discarded but deliberately sent into solar orbit or directed to crash into the Moon.
9. Lunar Module Extraction: Now, the Apollo spacecraft was ready for the Moon landing. A smaller spacecraft called the Lunar Module (LM) was extracted from inside the Service Module (SM) of the Apollo spacecraft. The LM would later descend to the lunar surface while the Command Module (CM) remained in lunar orbit.
In this way, the Apollo spacecraft utilized the power generated by its stages' rocket engines to overcome Earth's gravity and propel itself towards the Moon.