North Korea fires 'projectile'

[Bernardo de La Paz]

5. Several points remove the sense of strangeness

1) Height is not what makes orbit. Speed makes orbit. A certain height is needed to get out of the atmospheric drag to maintain orbit. If the earth had no atmosphere you could orbit a few feet (meters) above the height of Mount Everest.

2) The speed going down is about the same speed as going up. The rocket fuel is spent before the rocket leaves the atmosphere, so the re-entry speed is the same as the speed leaving the atmosphere.

3) However, there will be considerable aerodynamic drag unless the re-entry vehicle is bullet shaped, which it surely was, along with heat shielding because the speed and drag increases as it goes deeper into the atmosphere on re-entry.

4) Projectiles follow parabolic paths. The rocket is a projectile after it spends all its fuel. From that point up and over the top and down again it follows a parabola. When it gets down to the same level as the fuel ran out, it continues dead-heading on an extension of that parabola. To follow the path you describe would take considerable more power (fuel) and perhaps re-starting the engine.