Select the Sprite

Add Square.png as texture

Add a script to Bullet

Assign a class name

export a variable for speed

create a variable for direction

Code the signal to

Destroy the bullet 

Once off screen

The bullet scene can be used by the Player or the UFO

Create a function to assign it to the UFO

In the ready function

Set the angle of the bullet to match

Ship rotation

In the Player scene

Add a Marker2D node

Rename it to ShootingPoint

Place it at the tip

Of the Ship

Add a script to ShootingPoint

Assign a class name

Export access to the bullet scene

Create a function to shoot

If bullet scene is not assigned exit

Instantiate the bullet scene

Match the position and rotation

Of the ship or ufo

Add it to the Scene Tree

In the Player script

Add a reference to the ShootingPoint

In the process function

Add a check for shooting

Shoot if action pressed

In the Asteroid scene

Select the Asteroid node

Connect the area entered signal

Code the function to

Destroy the bullet

Call the on destroy function