“Gravity is one variable in a lot of scientific processes. If you can remove gravity or minimize its effect, then you can understand the other processes that are going on.” Laurel Clark; NASA astronaut and medical doctor Fractional flow reserve (FFR) is the gold standard for invasive assessment of hemodynamic severity of a coronary stenosis and it has been shown to improve clinical outcomes in randomized clinical trials [1] . Acknowledged pitfalls of FFR may originate from calibration, equalization, submaximal hyperemia, drifting, whipping, and wedging.