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Land on the Moon

Hold down the engine and set the lander down gently. On the Moon you have time, because gravity there is six times weaker than ours. Then try Mars, and then Earth.

  1. Press “Start the descent”: from then on the lander falls by itself.
  2. Watch the dashed line rising: when it reaches the lander, it is the last moment to fire the engine.
  3. Hold ENGINE until your speed drops below the landing limit, then set it down.
Where are you landing?

The engine pushes at 8 m/s² and gravity pulls at 1.6: you can brake, but you have to start about 129 feet before touchdown.

Altitude492 ftStarting from 492 feet
Speed16 ft/sLand below 6.6 ft/s
Fuel100%What is left is your score
No engine74 ft/sHow fast you would hit the ground falling
Moonthe last 98 feet take up half the drawing
The lander is 492 feet above the ground, coming down at 16 feet per second, with 100 percent of its fuel left.

The lander is waiting: press “Start the descent”.

Why you land gently on the Moon

The Moon’s gravity is 1.6 m/s², ours is 9.8: 6.1 times stronger. That means everything up there falls 6.1 times more slowly, and to fix a mistake you have 6.1 times the time you would have here. The lander is the same in all three places: the only thing that changes is how hard it is pulled down.

The black sky on the Moon is not a mistake in the drawing: with no air there is nothing to scatter the sunlight, so the sky stays black even in full daylight and you can still see the stars. Mars has air, but very little and full of dust, and the dust gives the sky its color.

On Earth, with this engine, you simply cannot brake. It is the same thing seen from the other side: to escape from the Moon 1.5 mi/s is enough, to escape from Earth you need 7.

The card: Apollo 11 · The card: how a rocket works

The numbers come from the NASA Planetary Fact Sheet, line by line.