Phaeton

Poul Anderson, Harvest Of Stars, 53.

Phaeton reminds us of Satan. When, every fourteen standard years, the planet passes near Alpha Centauri A:

frozen gas explodes into geysers and clouds;

melting ice becomes cataracts and floods;

coasts are "...drowned..." (p. 457);

there are hurricanes, rainstorms and lightning;

stones torrent from mountains;

there is blazing light and hard radiation.

Kyra and Rinndalir explore Phaeton when it is farthest from A and crusted in snow.

Inside Perun

Poul Anderson, Harvest Of Stars, 52.

When the interior of the asteroid has been fully developed, birds, moths and bats will fly free. There will be flowering vines and a stream running through a trench along a passage. Rock passages are "...polished glass-smooth..." (p. 451) and lit in changing colors. Sculptured pillars, "...studded with gems and crystals...," (p. 452) are animated by the variable light. In the light gravity, Lunarians jump between platforms in a downward shaft. Spreading his cloak, Rinndalir floats like a leaf. His spacious chamber has a viewdome ceiling showing the heavens, including Alpha Centauri A and B. As on Luna and Proserpina, the Lunarians transform stone chambers into paradisal habitats.

Lunarians In Centaurian Space

Poul Anderson, Harvest Of Stars, 52.

At Alpha Centauri, the Lunarians colonize the asteroids. Perun a thousand kilometers at its widest, is too small for cities, but does have a north polar spacefield approached by roads surrounded by domes, masts, pyramids and colonnades. The spacefield has hemicylindrical buildings and a control radar. The Lunarians have built much in few years and are now constructing a spaceship that might travel to Proxima Centauri and further.

Observe how Harvest Of Stars transcends its earlier chapters and also how much information is packed into each of the later chapters.

Demeter Before The Colonists Arrive

Poul Anderson, Harvest Of Stars, 48.

There are self-replicating robots, some controlled by downloaded human personalities. A flyer controlled by download Kyra Davis and carrying download Gabriel Berecz takes off from a landing field with hangers. Currently, Kyra, a former space pilot, is embodied in the flyer whereas Berecz, an ecologist, is inside a fieldwork body with caterpillar treads, telescopic sensors and many arms with diverse hands and is accompanied by "robugs" (p. 424)

Below, and around the planet, nanomachines reduce rock to mineral grains, then robots infuse synthesized humus into the grains. Wind carries organic matter onto the lower mountain slopes where rain mingles it with natural lithosols so that, with the addition of spores and seeds, moss and tussocks grow on the slopes. Terrestrial life will kill the animalcules in the Ionian Ocean. Port Fireball comprises buildings containing industrial and scientific facilities where the Taunus River enters Shelter Bay. Cooling towers rise from the fuel plant on Hydrogen Island. There are buildings, places and names without, as yet, a human community.

Imported earthworms, lacking natural enemies, multiply explosively, destabilizing gradients and causing a landslide from which Kyra barely rescues Berecz. Loosening of the substrate and the resultant chemical changes leach out alkalis, increasing the pH of the soil and thus killing vegetation. This can be corrected by adding appropriate substances to the humus. However:

other poisons will act;
bacteria will mutate;
some DNA will become viruses;
imbalances between species can be lethal;
the Demetrian ecology must become self-maintaining.

The Centaurian System

Poul Anderson, Harvest Of Stars, 40.

Alpha Centauri A and B are in orbit around each other;

Proxima, a red dwarf, discovered telescopically, is on a wider orbit;

(Beta Centauri, elsewhere in Centaurus, is the second brightest star in the constellation);

A had three planets but captured Phaeton from B;

A's outermost planet, Demeter, bears life;

B had two planets but lost Phaeton;

between A and B is the forbidden zone of chaotically orbiting asteroids;

Phaeton passed through the forbidden zone and now orbits A on retrograde comet-like ellipses that will make it collide with Demeter in a thousand years;

human beings will colonize Demeter;

Lunarians led by Rinndalir will colonize the Centaurian asteroids rather than staying in the Solar System where social evolution is not to their liking.