the effect appears to be a simply trail effect.
essentially, as you move along, you record several points(position, and direction of thruster, and a time to live for that point).
you generate a series of rectangles starting at the source thruster, and create a rectangle between the current point and the next point(using perpendicular direction from each points's recored rotation).
basically this diagram well hopefully explain it well enough:
to see the above method in action:
their are other ways(such as re-drawing the previous frame, but fading it out a bit, then draw the current frame).