# 03 - To the Mun

## Pages

## HW03

- Is posted
- Goal: Write a script to land on the Mun
- Three steps:
- Launch
- Transfer to Munar orbit.
- Land

## Part 1: Mostly Manual Mun Mission

## Part 2: Keplerian Mechanics

- Solid video: https://www.youtube.com/watch?v=AReKBoiph6g

## Part 3: Mun Mission Problems

### Landing Script

You can probalby get away with just landing wherever, and retry if you hit a
crazy slope or something.

One strategy is to calculate and execute a perfect "suicide burn", where you
burn at full throttle until you hit zero speed exactly when you hit zero
altitude.

Another strategy is to set a progressively lower maximum speed as the vessel
gets closer to the surface.

We can estimate start time by taking into account thrust, speed, distance, and
local gravity.

Example:

- We're at 100km
- We're falling at 1000 m/s
- We're accelerating at 10 m/s^2 due to gravity.
- We can thrust at 20 m/s^2 up
- That gives us the ability to slow at 10 m/s^2
- We'll hit in 100 seconds if we thrust to cancel our acceleration.
- We can slow to zero in 100 seconds.
- It's a little early for a suicide burn, but probably a good time
to start a more conservative burn.

### Transfer to Munar Orbit

Transfer burn:

- Start: In a low, circular-ish orbit, coplanar with the Mun.
- First, we want a transfer orbit - where our apoapsis will be in the Mun's SOI
when we get there.
- So we need to burn up our apoapsis to the Mun's altitude.
- Problem: Where in our orbit do we do the burn?
- Solution: On the opposite site of Kerbin to where the mun will be when we get
to apoapsis.
- Where will the Mun be? It'll get as much time to move as it takes us to get
there.

Orbit burn:

- Once we get to the Munar SOI, assuming we're not hitting the Mun, we need to
circularize at periapsis.