Apollo 11 (1969) flew a free-return trajectory—a carefully calculated path that looped around the Moon and naturally returned to Earth without major propulsion if systems failed. After trans-lunar injection (TLI), the spacecraft entered a translunar coast, performed lunar orbit insertion (LOI), and placed the Lunar Module into a low lunar orbit (~110 km circular). The descent to the Moon was initiated from this stable orbit, prioritizing precision landing over passive safety once LOI was complete. Apollo 13 (1970), initially planned similarly, became the most famous real-world validation of the free-return trajectory concept. After the service module failure, the crew used the Moon’s gravity as a slingshot, following a modified free-return path. Midcourse corrections using the Lunar Module propulsion system refined reentry targeting. The mission demonstrated how trajectory design can act as a built-in redundancy when propulsion and life support systems are compromised. Artemis II (pl...