Ostensibly launched as a scientific project to create a complex, self-sustaining ecosystem under a sealed dome in the Arizona desert, Biosphere 2 has received much derision from scientists since it was revealed that supplies were secretly imported and air pumped in after the Biosphereans were "sealed" inside. Commenting on the plummeting levels of oxygen inside the structure, which have caused some Biosphereans to reach for pure oxygen at night, Scott McMullen of Space Biosphere Ventures deflected charges that the experiment failed conceptually and instead reached more sweeping conclusions. McMullen cited a scientist who says that the Earth is losing 13 parts of oxygen per million a year: "It may be that Biosphere 2 is experiencing the same problem as the planet is."

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