Why does ion propulsion, which expels material much faster than ...

[Diane]

Why does ion propulsion, which expels material much faster than ordinary chemical rockets, hold such promise for future space travel?
 
  What will be an ideal response?

Question 2

Theoretical calculations suggest that Earth-sized planets could be habitable on their surfaces outside of habitable zones if they
 
  A) have thick, hydrogen atmospheres
  B) have thick carbon dioxide atmospheres
  C) are tidally heated by several large moons
  D) have larger irons cores

[mcinincha279]

Answer to Question 1

Much less fuel is needed since the same impulse can be delivered to the rocket by less mass expelled at greater speed.

Answer to Question 2

A

[Diane]

Thanks for the timely response, appreciate it

[T4T]

Excellent