Spacecraft life support and fuel cell systems utilize supercritical oxygen storage to maintain high fluid density while avoiding the handling and phase challenges associated with traditional liquid or high-pressure gas storage.
The retrieved papers provide direct technical evidence that spacecraft (such as Apollo) utilize supercritical oxygen and hydrogen stored in tanks where density is gaged via capacitance sensors. Furthermore, technical literature on aerospace life support confirms that storing gases like air and oxygen in a supercritical state achieves high-density storage at manageable pressures, directly supporting the claim.