Vacuum Chamber Outreach Demo: Boyle's Law & the Armstrong Limit

This is the classic space-education outreach demonstration rebuilt as a real 3D physics simulation: a bell-jar vacuum chamber holding a marshmallow and a droplet of water. Pump the chamber down and the marshmallow's trapped gas cells expand exactly as Boyle's Law predicts (V ∝ 1/P at constant temperature), while the water droplet's boiling point is recalculated live against the falling pressure until it crosses the Armstrong limit — about 6.3 kPa, the pressure at which body-temperature water boils without any added heat. That single threshold is the physiological floor every crewed spacecraft, space station module, and pressure suit is designed never to approach, which is exactly why this demo is used at outreach events to make the case for life-support pressurization engineering in one visual.