Is a vibration isolation system required for Gateway? Mitigation of force and vibration transmission by the HIFIm jump sled during repeated jumping in microgravity

Abstract Exercise countermeasures are a ubiquitous part of space habitation due to the need to mitigate the deconditioning effect of microgravity. However, exercise in space creates forces that need to be isolated from the habitat, and these so-called Vibration Isolation Systems (VIS) are typically large and heavy. High Frequency Impulse for Microgravity (HIFIm) is an exercise countermeasure that is designed to minimize force and vibration transmission to the spacecraft without the need for an additional VIS. The purpose of this study was to evaluate the effectiveness of HIFIm in mitigating force transmission in microgravity during parabolic flight. Force between HIFIm and the aircraft was measured using a custom-made arrangement of load cells during repeated jumping by two participants. Mean peak force transmission to the aircraft was 4.79 ± 0.68 N.kg-1. In addition, the frequency spectra for the upper and lower fixations to the aircraft were within the envelope of what is permissible for an exercise countermeasure on Gateway. These data support the design concept of HIFIm and suggest that HIFIm could be installed in a space habitat with no, or minimal, additional VIS. Measuring the force and vibration transmission of exercise countermeasures in microgravity during parabolic flight is highly challenging due to the safety constraints of the experimental platform and the extreme changes in acceleration (from 0-1.8g). The fact that this performance can be directly measured for HIFIm is a key advantage. The results presented here add to the mounting evidence that HIFIm is the future of exercise countermeasures.