Measuring the Mass of an Astronaut in Zero Gravity

Practical work (laboratory for student) : Measuring the mass of an astronaut in zero gravity is vital for the control of muscle and bone mass as well as maintaining a constant mass for extra-vehicular activity. How to measure the mass in weightlessness without balance. The activity is to obtain the mass of an object suspended from a spring . Measuring the period of the oscillating movement of the suspended mass and the knowledge of the spring constant used to obtain the weight. This lab can be done by the teacher as a demonstration or a students lab  in one class period.