Microgravity-induced changes in cardiovascular physiology are well-known and significant. Even short duration flights can lead to orthostatic intolerance, syncope, and reduced maximal oxygen uptake upon return to earth. In long-duration spaceflights, these effects can lead to the incapacity to egress the re-entry vehicle without help. Countermeasures, such as exercise or low body negative pressure application, are typically used to mitigate these effects. However, there is still a need for a simple method to monitor and quantify the cardiac de-compensation and the effectiveness of the counter-measures, as shown in the NASA Bioastronautics Roadmap. Our Stanford team has developed a non-invasive hemodynamic monitor based on the measurement of the ballistocardiogram (reaction force due to blood flow) using a weighing scale. This system has been thoroughly tested in multiple clinical trials, and has shown to be effective in monitoring changes in cardiac output, contractility and other cardiovascular parameters. Compared to other BCG monitors based on the recording of the free-floating body acceleration, this system has the advantage to allow recording both on the ground and in microgravity. This way, data measured in weightless environments can be interpreted in light of the large body of data that has been gathered on the ground, significantly facilitating the validation of the method. Moreover, this platform also enables the comparison of free-floating acceleration BCG to scale-based BCG, therefore providing a means to compare current studies of free-floating acceleration BCG (such as ESA-sponsored B3D program) with ground-based studies something currently not possible We propose to further the development of this technology and demonstrate its usefulness in microgravity in a series of parabolic flights. By flying a clinically-tested device used in many ground-based trials, we will be able to establish a correlation between ground-based and microgravity measurements. We plan on flying two setups, collecting data from six persons on each flight, over five days. From a TRL of 4, we expect to bring the system to a TRL of 6 following this campaign. In addition, the joint measurement of the free-floating acceleration BCG will provide key data towards the cross-validation of these two complementary modes of measurements, therefore advancing the wider community.