The Cycler Compact

In my novel Permanence I posit an interstellar civilization known as the Cycler Compact. The key feature of this civilization is that it depends crucially on cooperation between far-flung worlds.  This page describes how the system would work.

Let's begin at Jupiter. Some Ganymede colonists dismissed as lunatics decide to colonize the galaxy. They're not rich--just wealthy enough to manufacture several million kilometers' worth of wire, and boost it into Jupiter orbit. The energy from these wires is transformed into microwaves and beamed to a particle beam system powerful enough to accelerate a magnetic sail with no cargo to several percent of lightspeed. This is a preposterously weak system--you might send a probe to investigate the nearest star this way, but it would take a century to get there. Obviously, this "colonization" will never get off the ground.

The dreamers launch a simple device consisting of a magsail and some coiled Lorentz Force cables. The total mass of this system is only a few tonnes. It sails out of the solar system at max velocity--say, 3% lightspeed. Impressive, but at this rate it'll take about 150 years for it to get to Alpha Centauri. After the laughing stops, everybody forgets about this trivial exercise, even as the dreamers launch another magsail, and another.

Then, mysteriously, the first sail reappears--entering the solar system from the direction opposite to its departure! The dreamers explain that once it was on its way, the magsail uncoiled its Lorentz Force cables, charged them with the last energy from the particle beams, and began a slow turn. Now it's back.

The dreamers aim their particle beams at it again. It exits the solar system a second time travelling 6% lightspeed. A year or so later, their second sail comes by, and they repeat the process, and again with the next one.

During the waiting periods, the dreamers have not been idle. They've been manufacturing more wires, in fact, and orbiting them around Jupiter. Their particle beams are getting more and more powerful--the point where on the next "push", they succeed in accelerating the sails to a full 12% lightspeed.

By this time, the rest of the solar system is sitting up and taking notice.

With their sails moving at a goodly clip, the dreamers can move into the next phase of their project. The sails have slowly been converging out in deep space, and when they merge, nanotech assemblers dismantle two of the sail/wire systems, and use the materials to construct a set of "scaffolds" for future construction. They bleed energy off the particle beams on the next pass to do this. With only one sail in motion now, the dreamers--now known as the "colonists" because they're finally being taken seriously--can devote the beam time they had used on the second and third sails to accelerating small cargoes to catch up to the main sail. Their wire farm around Jupiter is now at maximum size, and they begin to invite investments from other solar colonies. A group at Mercury, where energy is cheap, signs on. On the next pass the cycler is kicked up to an impressive 25% lightspeed, but more importantly, small cargoes (one or two tonnes apiece) are being accelerated up to meet it every time it passes by, which it does with lesser and lesser frequency.

Every "cycle" the starship makes is a bigger circle, because its velocity keeps increasing. Eventually, after several decades of invested beamtime, the circle is big enough to intersect a "brown dwarf" system two and a half light years from Earth. This dwarf is several dozen times as massive as Jupiter, and its magnetic fields are commensurately stronger. It has a number of satellites, several of them as big as Mars, and most heated by tidal friction, as Europa and Io are at Jupiter.

On its first pass by this system, the cycler reconnoiters. On its next pass, it is considerably more massive, and the infrastructure for long-term life support is being constructed in small habitats clustered at the center of the magsail. At this point, some of the habitats and magsail structures split off from the main body, forming two cyclers. When they return to the solar system on their next pass, one will be accelerated again, widening its circle past the brown dwarf. The other will receive some large cargoes, among them a furled magsail with some mining robots and nanotech as its cargo.

When the slower cycler revisits the brown dwarf, it drops off its magsail cargo, which proceeds to "cycle" its way through the prodigious magnetic field of the brown dwarf, decelerating with each pass. Over a period of years or decades, it reduces its velocity to the point where it can rendezvous with some of the material in the ring of the dwarf. While it is doing this, its parent cycler is growing in mass with each pass by Earth. It is now a substantial space station, awaiting its first passengers.

The mining robots and nanotech sail among the lowest-mass objects orbiting the brown dwarf, harvesting metals. Their energy comes directly from the dwarf's magnetic field. They manufacture the simplest materials: wire, and microwave rectennas. As power begins to become available from the cables they orbit around the dwarf, they turn to manufacturing a bank of mesoparticle accelerators. These mesoparticle accelerators don't need to be very powerful; they just need to be able to send a concentrated beam of material out of the dwarf's gravity well. In fact, they're just glorified leaf blowers, sending fine dust in the direction of Earth at low velocity. The only high-tech thing manufactured by the robots is a laser, which they don't use yet.

The cycler approaches. This time, it carries a crew, and passengers, in fairly sumptuous accommodations. The crew were "uploaded" to the cycler as it passed Earth, in a low-mass rendezvous balloon. As the cycler approaches the dwarf it drops off a "cargo sail" magsail, which lines up with the mesoparticle beam. The cargo sail consists of a magsail, a balloon-like living structure and minimal life support and supplies for a crew of six humans. At a prearranged signal, the robots at the brown dwarf switch on their laser, and lightly ionize the mesoparticle beam in a spot just ahead of the approaching cargo sail. When the cargo sail slams into the mesoparticle beam, it begins decelerating rapidly. Its passengers endure a month or so of high-gee deceleration, and when it's over they've arrived at a new planetary system.

Each pass of the cycler brings more colonists, most from Jupiter who find the dwarf a familiar environment. Eventually, they are able to set their own cycler in motion, just like their parents did; they will build a thriving "cycler ring" between the dwarf and Earth.

While all of this has been going on, the original high-speed cycler has been accelerating with every pass by Earth. It is approaching 70% lightspeed, and there are now enough launchers operating in the solar system that it is not alone. Other cyclers are flying out to the stars, some following its route, others striking out on their own. The most effective strategy might be to launch cyclers along the same ring, but moving in the opposite direction to the first. In this way, two-way traffic between nearby systems can be established without the necessity of passengers going all the way round the ring to get back to their original system.

This original cycler has adjusted its trajectory to take it past our brown dwarf, and thence to a nearby stellar system. It doesn't matter whether this star is at all like the sun; it could be, say Wolf 359, a red dwarf one hundred thousandth as bright as the sun at 7.6 light years distance. The colonists aren't looking for another Earth; most of them grew up on Mars, or at Jupiter or in the asteroids. They are looking for Jovian planets with many moons; or terran planets of Martian size or larger, at any distance from the star. As long as they can harvest energy and raw materials, they can colonize. Jovian planets are the best homes, because it is easy to harvest electric power from their magnetic fields.

The cycler is now a miniature city, and it has built a magnetic ramscoop from the original magsail. It no longer receives a kick every time it passes Earth; now, it uses Lorentz Force turning and fusion power from hydrogen harvested from space to turn and maintain its velocity. The ramscoop also serves as an effective shield to the body of the cycler--but for maximum safety, the cycler is not a single vessel but several dozen vessels flying at distances of ten to a hundred kilometers from one another.

As it passes Wolf 359 the cycler drops off a cargo sail; in the future, every time it passes it will both drop off a cargo and pick one up, once the colonists at Wolf 359 have their own launchers working. Each cargo sail carries several dozen tonnes of mass; this is miniscule compared with the massive cyclers. It is well within the means of a young colony to build mesoparticle decelerators, and even at an early stage they can accelerate small cargoes to rendezvous with passing cyclers.

After passing Wolf 359 the cycler does a course correction. It uses both the Lorentz Force cables and fusion drives to do this. It aims at a new target: say, a newly discovered brown dwarf in between Wolf 359 and Luyten 726-8. It will pass both these destinations, dropping off cargoes, and then move on to Epsilon Eridani, a sunlike star 10 light years from Earth. For the passengers, each phase of the journey may have been short, as they might have travelled only between local dwarfs and small stars, 2 to 5 light years for each leg. The cycler has either been continually visited and refurbished along the way, or it has dropped its complete complement of passengers at a new colony and gone dormant as it curves its grand circle back toward Earth. In this way, in small stages, the full cycler ring is populated, without requiring the massive, throway starships and tragically final one-way journeys contemplated in the past.

As trading routes and political alliances develop, there become rings within rings, nested like the small one going between Earth and that first brown dwarf; and overlapping rings, and multiple tangential rings of varying sizes, all centered at major centers like Earth, Tau Ceti and Epsilon Eridani. The sun-like stars hold out the promise of Earthlike worlds, or worlds that could be terraformed; but the orphan worlds, brown dwarfs and Jovian planets that were ejected from their mother stars aeons ago, are the priceless way stations that make it possible to travel between the lit stars. For the foreseeable future, humanity will concentrate its exploratory efforts on finding these stepping-stone worlds.

Appendix:  Brown Dwarfs as Destinations

Just as Permanence was coming out, a study from the University of Leicester confirmed one of the key ideas of the novel: that brown dwarfs or supergiant planets can produce vast amounts of electrical power via their magnetic fields. In the novel this power is harvested to sustain civilizations around these dark wanderers.

The study, done at the University of Leicester, concerned the planet Jupiter, which has vast auroras over its poles. The study attempted to explain the origin of these auroras, and posited truly gargantuan electric circuit between Jupiter and the plasma fields around it. Professor Stan Cowley said, in a Particle Physics and Astronomy Research Council (PPARC) press release dated March 27, 2002:

The force associated with this electric current causes the plasma gas to spin at the same rate as the planet as it flows outwards. Our calculations suggest that the total current in this giant circuit is 100 million amps. The power transferred from the atmosphere to the plasma disk is about a thousand million megawatts or about 20,000 times the peak electricity demand in the UK!

The significance of this is that it overturns the notion that the "lit stars" are the only fit destinations for interstellar colonization.  It is very easy to harvest electricity from the plasma around brown dwarfs or Jovian planets--all you need is a long wire--and with electricity your colonists can have heat and light. (The definition of an electric generator is a wire in a moving magnetic field.) Since Jupiter is about 1/10th the size of the smallest brown dwarf described in the novel, you can imagine the power available to colonists or visitors to a dwarf.

Also intriguing is the idea that on a brown dwarf ten times Jupiter's mass but only twice the diameter (due to gravitational effects), the polar auroras might be much more intense than they are here (vastly greater current flow over almost the same area). Not bright enough to heat any moons orbiting the dwarf--though the dwarf may radiate enough infrared to do that anyway--but might the auroras be bright enough to see by? Maybe. Enough to sustain photosynthesis on the surface of a moon? Well, now I'm sticking my neck out... but it's fun to imagine what such a place would be like.