A constant force of 2854 N acts on a spacecraft of mass 6100 kg that has an initial velocity of 32 m/s. How far has the spacecraft traveled when it reaches a velocity of 1170 m/s?

I used: Vo=32 m/s, Vf=1170 m/s, F= 2854 N, and mass= 6100 kg

I then solved for a by taking N/kg... followed by using Vf=Vo + at... after that I did Xf=Xo+Vot+1/2at^2

This gave me a negative number that was wrong? Any advice?

a = 2584/6100 = .4236

1170 = 32 + .4236 t
t = 2686 seconds

x = 0 + 32 * .4286 + (1/2)(.4286)(2686)^2
= 1,157,000 meters or about 1,000 kilometers