The last thing we do is connect the two ends of the billion-mile-long O’Neill cylinder, so that now you have a loop. Or, as in Heaven’s River, a billion miles. After all, for any given diameter, a length of ten miles isn’t any more of an engineering challenge that one mile.

Think of a topopolis as an O’Neill cylinder stretched to a ridiculous length. But with a single cylinder, you can enter and exit through the ends, preferably along the axis where there’s no pseudo-gravity. In order to keep the outer shell and the inner cylinder from touching, we place magnetic bearings in the gap. We make it non-rotating and separate from the cylinder so that it doesn’t place a load on the cylinder. So stick a non-rotating shell around the cylinder, made of rock or other friable material, to absorb meteor impacts. And like Johanssen said in The Martian, we need air to not die. One good meteor punch and all the air drains out of the cylinder. That’s great, but possibly a little exposed. There are different designs for introducing light into the cylinder, but the one used in Heaven’s River is a fusion-powered light source on a structure that runs down the center of the cylinder. An O’Neill cylinder, at its most basic, is just a large drum, rotating around its axis to create centrifugal pseudo-gravity on the inside surface. I’ve seen a few comments that Heaven’s River is not sufficiently well described in the book, so I’ve put together this post to describe it in more detail.įirst, let’s start with an O’Neill cylinder, something most people are far more familiar with. All it will take to save the Earth and perhaps all of humanity is for them to get it to Sol - unless the Others arrive first.If you haven’t read the book yet, best stop now. A couple of eighth-generation Bobs have found something out in deep space. Yet salvation may come from an unlikely source. But the Bobs are less disciplined than a herd of cats, and some of the younger copies are more concerned with their own local problems than defeating the Others. Still stinging from getting their collective butts kicked in their first encounter with the Others, the Bobs now face the prospect of a decisive final battle to defend Earth and its colonies. And the Bobs have picked a fight with an older, more powerful species with a large appetite and a short temper. But political squabbles have a bad habit of dying hard, and the Brazilian probes are still trying to take out the competition. They've created enough colonies so humanity shouldn't go extinct. But after spreading out through space for almost a century, Bob and his clones just can't stay out of trouble.

Being a sentient spaceship really should be more fun.

Bobiverse all these worlds