The Space Scale: An Instrument for Astronaut Mass Measurement

Abstract

A practical, high-precision method for measuring the mass of an astronaut under microgravity conditions is proposed. Using an instrument called the ''Space Scale'', the velocities of a target object and a reference mass are measured with high accuracy by optical interferometry. The two are connected by a linear ball bearing and have separate linearmotion states, with some acceleration due to friction in the linear ball bearing. For this paper, a ground instrument was developed in which linear motion of the whole mechanical system is achieved with negligible external force by means of a pneumatic linear bearing. The effect of linear ball bearing friction that involves the target object and the reference mass is theoretically negligible, as we proved experimentally in this study. We conclude that an operational model for in-orbit use, which takes advantage of an optical interferometer, would be extremely compact and accurate.

Reconsideration of Body Mass Measurement on the International Space Station and Beyond

“…Based on "Space Scale" principle (Fujii and Shimada, 2006), prototype ground model was submitted for precision estimation. This design incorporates an attachment of an elastic spring to the vicinity of human body center of gravity, laser interferometry distance measurement that makes it a compact device, and a force sensor to record the tension of the elastic spring.…”

Precision Mechanical Measurement Using the Levitation Mass Method (LMM)

“…The author has modified it as calibration methods for all the three categories of the dynamic force calibration [1][2][3][4][5] , that are the dynamic calibration method under impact load 1) , the dynamic calibration method under oscillation load 2) and the dynamic calibration method under step load 3) . The authors have applied the LMM for material testing, such as methods for evaluating material viscoelasticity under an oscillating load 6) and under an impact load 7,8) , a method for evaluating material friction 9,10) , a method for evaluating biomechanics 11,12) , a method for evaluating a dynamic performance of a liner motor 13) , mass measurement device (MMD) for use in the International Space Station (ISS) [14][15][16][17][18] , a method for evaluating dynamic response of impact hammers 19) , a method for generating and measuring a micro-Newton level forces [20][21][22][23] . The author has also applied the LMM as a method for investigating the frictional characteristics of pneumatic linear bearings 24,25) and the linear ball bearing 26,27) .…”

Evaluation of Frictional Characteristics of Aerostatic Liner Bearing

“…The author has modified it as calibration methods for all the three categories of the dynamic force calibration [8][9][10], that are the dynamic calibration method under impact load [8], the dynamic calibration method under oscillation load [9] and the dynamic calibration method under step load [10]. The authors have applied the LMM for material testing, such as methods for evaluating material viscoelasticity under an oscillating load [11] and under an impact load [12,13], a method for evaluating biomechanics [14][15][16][17], a method for evaluating dynamic response of impact hammers [18] and a method for generating and measuring a micro-Newton level forces [19][20][21][22]. To improve the efficiency of the LMM, a pendulum mechanism [23] for use as a substitute of a pneumatic linear bearing and a frequency measurement technique [24,25] using a digitizer instead of an electronic frequency counter have been developed.…”