I know on the moon there’s less gravity but how could they perform a launch on the moon?
Sorry for bad English.
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Less gravity and no atmosphere. So they needed far less thrust to get back into their ship that was in lunar orbit for their return to earth.
The combination low gravity and no atmosphere meant that very little fuel (in comparison to launching from earth) is required, and the lower stage of the lunar module was left behind.
They brought a (much smaller) rocket with them onto the surface, and used it to launch themselves back into orbit. They then hooked up to the part that didn’t land, and came back home.
The command module of Apollo 11 remained in orbit, while the lunar module took 2 astronauts to the moon’s surface. When they left the moon, they only needed enough fuel to launch the lunar module back into the moon’s orbit, where it docked with the command module. Apollo 11 then returned to Earth
Module is fairly light, very little gravity and air resistance, once off the Moon they basically then fall to Earth.
The part of the rocket that launched the astronauts from the surface of the moon to lunar orbit only had enough power/fuel to do that task.
They met up with a larger spacecraft which got them back to earth.
The part that actually landed was in turn just a small pierce of this spaceship – just a capsule with a heat-shield and parachutes.
Your intuition is correct that they did not have enough power to get directly from the moon’s surface back to earth directly.
I understand all the answers and accept them but it feels like there was a good chance they weren’t going to come back. They were successful on the first try, the very first rocket launch on the moon with completely new conditions. I wouldn’t have gone if I was them.
The way the Apollo missions worked was the craft that launched from Earth had two separate parts, the command module, which carried the three man crew from the Earth to the Moon and back, and the lunar module, which took two of the crew to land on the moon and then rendezvous back with the command module. This meant the lunar module didn’t have to carry many supplies (which was the source of some drama with Apollo 13) which meant it was lighter. Also the Earth’s gravity is 6 times stronger than the Moon’s, plus the Moon doesn’t have an atmosphere and atmospheric drag socks up a lot of energy when launching from Earth. Also adding even a little bit of weight means you need a lot more fuel, because not only do you need extra fuel to carry that weight but you also need more fuel to carry the extra fuel, then you need more fuel to carry that fuel and so on. This all adds up to needing a ginormous rocket to take off from Earth, but the lunar module only needed a much smaller rocket to take off from the Moon.
They landed their spaceship on the moon with the rocket engines facing down. When it was time to leave the moon, they just turned them on and up they went!
The Lunar Lander had enough fuel to take off again and reconnect with the Command Module, the top bit of the rocket that was in orbit around the Moon (where Michael Collins was waiting). That then had enough fuel to return to Earth.
The Moon’s gravity is less than a fifth of Earth’s gravity, and it has no atmosphere (well, almost none) so you don’t need a massive rocket to take off. A tiny little craft like the Lunar lander is enough to get up into orbit.
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