Project: Lunar Lander

Lesson 11 of 11 · 8 min · Free, no account needed

What you will learn

A lander hovers when thrust equals weight: T = m g, 3240 N for 2000 kg on the Moon.
Thrust bigger than the weight slows a falling lander; smaller lets it speed up. The net force sets the acceleration: a = (T - m g) ÷ m.
The area under the speed graph is the distance fallen, and braking takes distance: from 10 m/s at 2 m/s² it takes 25 m.

Apollo 11 touched down with only seconds of fuel to spare. Can you land with fuel left?
Fly it yourself first. 120 m up, already falling at 6 m/s.
Three moments of a landing. Set the thrust arrow on each lander.
Weight is fixed. How long is the thrust (up) in each case?
Find the hover thrust: turn it until the lander stops speeding up or slowing down.
A 2000 kg lander hovers on the Moon (g = 1.62 m/s²). What thrust, in newtons?
Plan your landing: draw the speed you want at each moment.
100 m up, at rest. The autopilot will follow your line.
The autopilot flies your plan. Press Play.
A friend's plan crashes: engine off, then full brake too late. Move the brake.
Challenge: the same last 100 m on the Moon and on Mars. Which needs more fuel?
Code: finish the autopilot. Too fast: brake hard. Slow enough: hover.
v is the speed down in m/s, h the height in m. One loop turn is one second.
Another crash report. Tap the moment the engine started braking.
Falling at 10 m/s with 2 m/s² of braking: how high must braking start?
Your best landing, replayed. Press Play.

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