Ishtar's Necklace

Ancient Xeno Megastructure in the Carina Rush

Ishtar's Necklace
Image from Steve Bowers
Despite its size, the Necklace is dark and difficult to observe, even nearby


Ishtar's Necklace is a xenosophont megastructure in the Carina Rush with an estimated age of 1.3 billion years, apparently constructed from a dismantled red dwarf star. It came within in the colonisation wavefront of Terragen civilisation sometime in the 6800s due to the Carina wormhole. However, even after its initial discovery, it spent many centuries unknown to most of the civilised galaxy due to its low emissions, only attracting occasional colonists from various cultures. Over time these formed a unique civilisation. Eventual discovery by the Zerzavecs led to connection with the Nexus in 9334. Since then, Ishtar's Necklace has remained staunchly independent from the Carina Big Three and other powerful Carina Interests. Carina Big Three are composed of Zerzavec commune, Palladium Net, and the Carina Cycler Union.

The Megastructure

The necklace is a two part structure, consisting of a pressurised tube in a toroidal knot configuration, similar to a non-rotating topopolis or a large Niven cloud. These two parts are the Necklace proper and the Eye, a former red dwarf that has being converted into a construct similar to the one at Turing, albeit much smaller.

The Eye is a cluster of around 108 gravitationally bound chunks of hydrogen ice, each massing around 1021 kg and 16 black holes each of mass 1020 kg (apparently former DWIZs) occupying a roughly spherical region approximately 100 million km across.

The Necklace proper orbits at an average distance of 1.9 billion km encircling the Eye 128 times with a minor radius of 1200 km, giving a habitable volume of 6.9x1018 km3 and a mass of approximately 1028 kg. The interior is pressurised and segmented into lengths of approximately 200,000km; because the Necklace does not rotate, these chambers are microgravity environments. The barriers between segments are composed of a form of self-repairing smart matter resembling terragen airwall utility fog that keep the different environments separate, and may on occasion move location. The barriers may not be immediately noticeable, and sometimes can only be inferred by a sharp change in the local pressure or atmospheric composition.

The atmospheres inside these chambers are often similar to those found on various Gaian type worlds, being a mixture of oxygen, nitrogen, carbon dioxide and water vapour in a range of different ratios and temperatures (some of which resemble Tohulian atmospheric types). Segments with atmospheres of inert gases, halogens or other such exoticisms are known to exist, though these are much rarer and often shorter than the standard mix. A mesh of linear luminaires lies throughout the Necklace illuminating different segments to varying degrees in varying spectra.


Throughout its length the Necklace contains a number of very different and usually incompatible ecologies separated by many thousands of kilometres of lifeless tube. Some of these appear to have developed from the original biota of the builders, others have come into existence since then. Most of the ecologies are microbiological. There are some fairly advanced nanecologies, one highly developed ecology that seems to include both biotech and drytech components, and one mechosphere that has lead to the evolution of a presapient species - the Screethraw.


Ishtar's Necklace appears to have been initially settled by a group of provolved corvid hiders or isolationists sometime in the 6900s. Little is known about this group other than that they must have traveled via the Carina wormhole network and had no contact with the Screethraw.

They were joined in 7200 by a colonisation effort from one of the Brown Dwarf Cyberdemocracies, a nearbaseline population with several slaved hyperturings. The colonists did a more thorough search of the Necklace, discovering both the extant Corvid civilisation and the mechosphere containing the Screethraw. Contact between the two groups did not go well initially, and the Cyberdemocracy colonists decided to settle elsewhere. Nevertheless, they retained a number of spacecraft and were able to travel to distant parts of the Necklace and thus eventually contact and trade was established between the Cyberdemocracy colonists and the Corvid civilisation. A joint research team was able to provolve the Screethraw (named by one of the Corvid scientists) in 7650. Over the following centuries, a proliferating number of small polities spread throughout the ring, eventually forming the United Ishtar Polities, which grew from a loose trade federation to an increasingly tight knit empire, eventually beginning to ossify and establishing a formal dominion over most of the Necklace.

In 8381 a ship from the Zerzavec Commune arrived at the Necklace, having discovered a mention of it in the CCU archives, and established contact with the Ishtar Polities. A number of interesting biosphere segments were claimed in the name of the Commune for the Zerzavecs to live in. The Ishtar polities could do little to stop this, given that the Zerzavec ship had a S:2 transapient mind on board; and besides, the Zerzavecs were very diplomatic and wanted little of the Necklace.

The Zerzavec outpost and the Ishtar polities lived side by side for several centuries. During this time, the Zerzavecs became increasingly interested by the Screethraw, considering them in light of their own doctrines, and the Ishtar polities continued to ossify.

The United Ishtar Polities fragmented in the 8580s leading to a number of diverse independent nations. Some of these tried to establish a power base, and fragmented in turn. Though there no single large battle, violence erupted several times. The Zerzavec aioid Power was integral in restoring order before many lives were lost. In the reconstruction, a loose confederation of individual segments formed. Each segment was independent in its own internal affairs with segments associating freely to work on external issues.

The Zerzavec fascination with the Screethraw mechosphere continued during the political turmoil. Over time, some abandoned their previous biological augmentations and began experimenting with Screethraw cell unit additions instead. There was a peaceful schism in 8720, during which the heretic Zerzavecs broke away from the Commune and began to interpret the old principles in light of the Screethraw mechasphere. The two Zerzavec cultures continue to exist amiably alongside one another to this day.

Eventually the Necklace was connected to the Nexus via a microgauge wormhole in 9334, and to the Beamrider network in 9500. Despite this, the Necklace has maintained a strong independence from any of the local cultures - the only affiliation being of the orthodox Zerzavecs to the Commune.

Recently a number of outside groups have developed a strong interest in the Necklace. Colonists, developers, biologists, archaeologists and ecotects have all been traveling to the Necklace, and the CCU has not been shy about advertising its beamrider route to this treasure. There is some concern that this influx of outsiders may destroy the novelty of Necklace culture. Though it has so far managed to hold onto most of its uniqueness, the influence of outside cultures is visibly growing.

Culture and Society

The Necklace is home to a number of diverse cultures spread throughout its structure, though some broad statements can be made about the majority of settled segments. The collapse of the United Polities has lead to a distrust of large centralised entities and a strong libertarian streak. Even today, it is not unusual for disaffected groups to leave their segment and settle a new one.

The cooperation of cultures throughout the Necklace's history, and the interaction with the Screethraw, has lead to a tolerance for diversity and a sense of free interdependence.

Zerzavec influence shows strongly. The comparative stability of their culture during the collapse of the Ishtar United Polities, and then the later peacefulness of the schism has lead to a wide appreciation of Zerzavec principles throughout the Necklace, but interpreted in massively unorthodox ways. Practical principles now consider the ideal and optimum way to live, rather like a synthesis of Confucianism and Epicureanism.

All of these are just general trends, however. Many segments have their own idiosyncratic mystical belief systems, are xenophobic, believe themselves to be the successor to the Ishtar United Polities, and so forth.

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Development Notes
Text by Liam Jones
Initially published on 06 June 2011.