Thank you to Jack Varga (on Larch-L) for drawing attention to Nasa’s ideas on space colonies (see explanation and examples). They remind me of Sarah Eberle’s built example at the 2007 Chelsea Flower Show. But the Nasa examples are oddly suburban, as if humans would invest in travelling the universe to enjoy the delights of a modernist Levittown at high densities. Why would they need roofs if living in tubes? To protect from artificial rain? But it is probably correct that humans would soon tire of inter-galactic marvels and gaze instead at what the neighbours are up to – and that interest would help sustain tube life. It might in fact be a better idea to dispatch a spatter of tiny rockets containing only DNA, and this might be how life came to Planet Earth 3.5 billion years ago. My plea to Nasa is to send un-manned observatories into deep space – not humans.