| Traveling from the surface of the Earth to surface | | | | Moon. The speed must be high enough to leave |
| of the Moon in 5 steps. | | | | Earth's gravity completely, with some speed leftover. |
| 1. Launch from the Earth's surface to reach Low | | | | Then, the long distance to the moon, is actually |
| Earth Orbit. | | | | calculated as an orbit around the Sun. That is because |
| The first step on any ambitious adventure is typically | | | | the Sun's gravity overpowers the gravity of the |
| the hardest. Step 1 is no exception, and is by far the | | | | Earth and Moon. |
| hardest step. The rocket, fuel, and payload makes up | | | | The last speed consideration is the Moon. Fuel is |
| the three major components. On the launch pad, the | | | | expensive and heavy, the less you take the better. |
| fuel can take up 90% of the total weight, leaving | | | | But the Moon is much smaller than the Earth, so its |
| just 10% for the rocket and payload. That is the | | | | gravity is much weaker. Therefore, you need fly just |
| cost of accelerating to 5 miles per second, and the | | | | slow enough to allow the Moon to catch you in its |
| reason rockets are so big, when the payload can be | | | | gravity. That's why it takes three days to travel to |
| as small as a few people. At that speed, the rocket | | | | the moon. Travel any faster, the rocket will need |
| will be less than half its weight, or half its mass, and | | | | extra fuel to slow down. No brakes in space. |
| circling the Earth. In preparation for step two, the | | | | 4. Launch from Transfer Orbit to Moon Orbit. |
| rocket gets rid of the parts of itself that brought it | | | | Once you are close to the Moon, your orbit around |
| here. | | | | the Sun becomes your orbit around the Moon. |
| 2. Launch from Low Earth Orbit to High Earth Orbit. | | | | Gravity's pull rises as you approach the moon, so you |
| This step requires the rocket to accelerate again to | | | | speed up a little bit. |
| go even higher, much higher than in the previous | | | | 5. Launch from Low Moon Orbit to the Moon's |
| step. However, having less than half the mass, there | | | | surface. |
| is less to carry. Plus, the higher you go, the weaker | | | | Now to land on the Moon. You need to slow down, |
| the Earth's gravitational pull becomes, making the job | | | | or speed up in the opposite direction of your orbit. |
| easier. | | | | That is why even this step is still a 'Launch.' Once |
| 3. Launch from High Earth Orbit to Transfer Orbit. | | | | complete, you should be hanging somewhere high |
| Three items are considered in determining the speed | | | | above the Moon's surface, where the rocket slowly |
| for this journey, in chronological order: Earth; Sun; | | | | and safely descends and lands. |