Determine the fuel needed to safely land a spacecraft.

Start at y = 100km. Landing is y = 0km.
Vy < 25 m/sec is a safe landing speed.

g = -1.354 m/s^2

Acceleration due to thrust (where fuel used is 100 kgs*Ay-thrust
Amax = 30 m/s^2
Amin = 5 m/s^2

What I don't understand is the acceleration due to thrust part. This is all the information our professor gave. The planet that this is based off is Titan.