DM+39 4567 on the fringes of the stellar cluster known as the Varteq Veil. That sphere had been broken apart by gravitational asymmetries, the massive fragments forming a slowly expanding globe around its sun. The same catastrophe had destroyed the civilization that had built it, an entire race broken on the wheel of its own ambition. Bernice remembered standing on the surface of one of the fragments during an eclipse caused by a smaller fragment occluding the sun. In the sudden darkness the thin atmosphere gave the sky a cold hallucinatory clarity. The other fragments were bright with reflected sunlight, carving up the sky into crazy-paving shapes. Bernice could see surface features on the closer ones. An ocean that had survived the break-up, shrinking in from its artificial shoreline as it evaporated in the thinning atmosphere; a city bisected by the edge of one fragment. Bernice looked further on to find the other half and there on the next fragment was the rest of the city, glittering under a mantle of frozen oxygen. The nearer fragments appeared as flat as tea trays, the curve of the sphere being so gradual that it was only visible on the most distant fragments. The geophysics team had constructed a computer model of the break-up and ran a book on the results. The whole archaeology team had put money on their own time estimates. The crew of the freighter they were using for transport refused to bet. They thought the whole idea was distasteful; for them a catastrophic failure in life support was too serious, wherever it happened.
They didn't have the same perspective on life and death as the archaeologists. Bernice put her bundle on ten years, give or take six months. With a flair for the dramatic the geophysics team announced the results on the 'night' of the eclipse. All the surface-based archaeology teams gathered for a party. A bonfire was built with an oxygen feed to help it burn in the thin atmosphere. The palaeobotany team jury rigged one of their bio-reactors to brew beer and the xenobiology team roasted a couple of quadrupeds which they swore blind weren't sentient. They were more evasive about the animal's general edibility. Everyone lost their money. The computer model estimated that the break-up had taken two hundred and fifty years, from the first instability to actual disintegration of the outer shell. As they drank the passable beer and carved off sections of roast meat an argument broke out over whether it was actually possible to build a functioning Dyson sphere. Geophysics thought not and produced reams of statistics to back themselves up. The ethnotechnologists thought that someone somewhere was bound to have a go. The group sociologist, the only Indigenous Terran amongst them, said it was unlikely that a species that had evolved on a planet would ever feel completely comfortable on an artificial world. The local clan of Builders, perhaps a couple of medium-sized family groups, came to observe the archaeologists from a safe distance. Occasionally Bernice would catch glimpses of firelight dully reflected off the curve of a carapace or flickering in one of their large, mournful eyes. She wondered exactly when their ancestors had realized it was all going horribly wrong. Two hundred and fifty years. It was a long time to know you were dying. The Doctor led them up a narrow path through the forest. Roz and Chris, smug in their adjudicator's armour, simply flipped down their nightscope visors and followed easily. Bernice cursed and stumbled until she thought to surreptitiously grab the hem of Chris's robe and let him guide her between the trees. She had little sense of how far they walked, mostly uphill, although the path occasionally switched back and forth as if following the line of a ridge. There were occasional glimpses of wooded skyline silhouetted against those sections of the sky that were still in daylight. Once she thought she saw a trio of wind turbines on a distant hilltop, their