Half a mile beneath the desert of Carlsbad, New Mexico, a once-dense tube of super-chilled liquid xenon has been drained, its contents warmed and waiting in temporary storage bottles.

Although xenon rarely does much anyway (it’s one of the famed “noble gases” that tend not to engage in chemical reactions), this batch of xenon is particularly quiet. Its purpose for being there – a massive, international scientific experiment called EXO-200 – has halted for the foreseeable future following a series of accidents at the site.

The accidents in Carlsbad, though unrelated to the EXO-200 scientific effort, have made it unsafe for researchers to access the site to monitor and maintain the experiment. While the recovery process is underway, the scientists wait, not knowing when they will be able to resume their experiments and hoped-for observations of a certain, particularly rare – perhaps impossibly so – radioactive decay of the…