3. Lesson 3 - Luna 3

The far side of the Moon

These are the lunar phases we see:

• 🌑 = New Moon
• 🌒 = Waxing Crescent
• 🌓 = First Quarter
• 🌔 = Waxing Gibbous (approaching Full Moon)
• 🌕 = Full Moon
• 🌖 = Waning Gibbous (after Full Moon)
• 🌗 = Third (Final) Quarter
• 🌘 = Waning Crescent

When we look at the sky, especially at night, we can see the Moon. What many people don’t know is that we always see the same side of it.

As shown in the image above, one side of the Moon always faces Earth. You can imagine it like a coin that always shows the same face to us, even though it has another side. This is often called the “far side” of the Moon.

People sometimes call it the “dark side” of the Moon, but this is not correct. Both sides of the Moon receive sunlight. During a new moon, the side facing us is not lit, which is why we cannot see it.

This effect, where the Moon rotates in sync with Earth, is called synchronous rotation.

Luna 3 was the first spacecraft, launched in 1959, to travel around the Moon and take pictures of its far side. The mission faced several challenges - some equipment stopped working early, and the spacecraft experienced a drop in temperature. After circling the Moon, the signal was very weak, so the spacecraft had to carefully point its antenna toward Earth to send the photos before re-entering the atmosphere.

The "await" command in LEGO SPIKE Python

The await command tells your robot:
“Wait until this action is finished, then continue!”

Why use "await"?

• Motors need time to move
• Sounds need time to play
• Sensors need time to read values

Without "await", the robot may move on too quickly and not finish its actions properly.

Important rule

You can only use "await" inside an "async" function.

async def main():
    await motor.run_for_time(port.A, 1000, 1000)

How to use the SPIKE Python API

Here you can find a cheat sheet with the most commonly used commands. There are also more advanced commands that are not included in the built-in API, but the available ones cover most, if not all, of the students’ needs.

Below is an example of a function definition and how to read it:

Let’s take a closer look at the function definition:

The parameters before the "*" symbol are required parameters. You must provide them in the correct order. For example, the first parameter is "pair", so the command expects the motor pair first. The same applies to "degrees" and "steering".

The parameters after the "*" symbol are optional parameters. To change them, you must use their names. This means you cannot just write a number - you need to specify which parameter you are changing. For example:

motor_pair.move_for_degrees(motor_pair.PAIR_1, 360, 0, velocity=280)

Finally, the "Awaitable" keyword means that this command can be used with "await". This allows the program to wait until the command has finished before continuing with the next one. For example:

await motor_pair.move_for_degrees(motor_pair.PAIR_1, 360, 0, velocity=280)

Motor pairs and the "move_for_time()" command

A Motor Pair connects two motors so they can be controlled together. Here is how to do it:

Set up the motors

To create a motor pair, we use the command motor_pair.pair(). Here is an example:

from hub import port
import runloop
import motor_pair

async def main():
    # Pair motors on ports F and D
    motor_pair.pair(motor_pair.PAIR_1, port.F, port.D)

The inputs of the motor_pair.pair() command are:

• First input = Pair number (motor_pair.PAIR_1)
• Second input = Left motor port (port.F)
• Third input = Right motor port (port.D)

The move_for_time() command

This command allows the robot to move for a set amount of time using both motors. Here is an example:

from hub import port
import runloop
import motor_pair

async def main():
    # Pair motors on port F and D
    motor_pair.pair(motor_pair.PAIR_1, port.F, port.D)

    # Move straight at default velocity for 1 second
    await motor_pair.move_for_time(motor_pair.PAIR_1, 1000, 0)

runloop.run(main())

The inputs of the move_for_time() command are:

• First input = Pair number (motor_pair.PAIR_1)
• Second input = Duration in milliseconds
• Third input = Steering value (from -100 to 100)

The velocity parameter is optional. To change it, you must specify its name:

motor_pair.move_for_time(motor_pair.PAIR_1, 1000, 0, velocity=280)