A person who has a weight of 159 pound-force [lbf] on Earth is travelling to Mars in a spacecraft. As long as the engines on the spacecraft are not operating, the person is essentially weightless during the voyage. During a course correction, the spacecraft undergoes an acceleration of 0.74 g. The term "g" is the Earth-normal gravity, so 1 g is 9.8 meters per second squared [m/s2]. This acceleration makes it feel like there is gravity in the spacecraft, and the person will have a perceived weight during the acceleration period, rather than feeling weightless. What is the person's mass, in units of kilograms [kg], in the spacecraft while travelling to Mars when the engines are not running?