Unperturbed, you press on and add some baubles. They hang at unusual angles – some are upside down, while others point sideways. The final flourish is a string of tinsel, which immediately disintegrates just as it would on Earth, leaving tiny bits sailing across the room and, rather ominously, making their way towards the air filters. You take a step back (or really, a clumsy weightless glide) and survey your work. Sure, the tree looks a bit haphazard – it"s wonky, because it doesn"t know which way is up – but the space station looks more Christmassy already.