Barnard's Star f (Barnard Waystation)

What a waystation is

Level 2 carriers must surface roughly every light-year: they drop out of warp to take a star fix, shed heat, and dump their bow load. Most surfacings happen in empty space and last an hour or two. A waystation is a place where surfacing is worth more than that: a stop inside a star system where ships can also refuel, repair, trade, and swap passengers and hitchhikers. Barnard's Star sits almost exactly on the straight line from Sol to 70 Ophiuchi (5.97 ly out, then 10.65 ly on), so every ship bound for Retinal or beyond stops here.

The star

Barnard's Star is the fastest-moving star across Earth's sky and is slowly approaching the Sun. In about 10,000 years it will be only 3.8 ly away. Waystation old-timers like to say the stop is "coming to meet you". Its four known inner planets (b, c, d, e) are small, scorched rocks orbiting within a few days of the star.

The planet

Barnard's Star f is the fifth planet found in the system: a rocky world under a thick shell of ice. It has no atmosphere, but not because it never had one. At these temperatures, nitrogen and carbon monoxide freeze solid. What was once its atmosphere now lies on the ground as frost, as on Pluto and Triton, mostly gathered in shadowed hollows and around the poles.

The grey surface: dust over ice

Most of the planet looks like a grey, dusty moonscape, but underneath the dust is ice.

• Where the dust comes from. Billions of years of impacts have shattered the rocky ridges and the rock beneath the ice, spraying fine grey rock powder across the surface. Dust from space adds to it.
• Why it collects. The planet's orbit is slightly oval, so over its 7-year year it warms and cools a little. The nitrogen and carbon monoxide frosts slowly shift from warmer ground to colder ground and back. Each time the frost moves on, it leaves its trapped dust behind. Over billions of years this has built up a blanket of grey dust, a few centimetres thick on slopes and metres deep in basins.
• What it looks like. Grey, powdery ground with the texture of the lunar surface. Footprints and tracks last for years. Where the dust has slid off steep slopes or been blasted away by landings, the ice beneath shows through as pale grey-white. There are also dark ridges of bare rock, and bright frost fields in the shadows.
• It stays grey. Frost of methane would turn reddish-brown over time, as on Pluto. But this world holds very little methane, so the dust keeps its neutral grey.

The green veins

Running through the dark rock ridges, crater walls and fault cliffs are veins of vivid green ore.

• What it is. A green nickel- and magnesium-rich mineral, similar to garnierite, a real nickel ore from Earth. It's found with dark green serpentine rock and traces of cobalt and chromium.
• How it formed. When the planet was young, it still had internal heat. Water circulated through cracks in its dark, iron- and magnesium-rich rock and altered it. The same process creates green serpentine rock on Earth's ocean floor. The warm water dissolved nickel from the rock and deposited it as bright green mineral along the cracks, forming veins.
• Where you see it. Anywhere the grey dust has been stripped off and bare rock shows: impact craters that punched through the ice, cliffs along cracks in the ice shell, and rock blocks heaved up through the ice. Under the station's white floodlights the veins shine a clear, rich green. In natural starlight they look muted olive.
• What miners call it. "The green."
• Story hook: the rock that made these veins was once soaked in warm water, and on Earth, places like that are leading candidates for where life began. So the waystation sits on a world that may once have been habitable deep down. Someone could go looking for traces of that ancient life.

Sky and light

Barnard's Star is about as hot as an old incandescent bulb, so its light looks like warm lamplight rather than deep red. From 2 AU it's a tiny brilliant point, too small to see as a disc, and its light is dim: roughly deep twilight on Earth. Colours are muted, the grey dust takes on a faint warm tint, and shadows are black. The sky is black and full of stars even at "noon". The waystation's white floodlights and beacons are the brightest things on the planet. They show the true colours: grey dust, pale ice, and the green veins.

Resources

• Water ice (the main business). Melted ice is both propellant for the plasma engines and the source of deuterium for reactors. Like Krysto's, this ice formed in the deep cold, so it is enriched in deuterium.
• Tritium, bred on site. Tritium can't be mined, because it decays within years. Instead, the station's big deuterium reactors breed it: some reactions make tritium directly, and the reactors' spare neutrons turn lithium, extracted from the rock beneath the ice, into more. This supplies the small tritium-burning craft that hitch through.
• Frozen nitrogen from the surface frosts provides breathing air for the station and for passing ships.
• Surface grit holds a little helium-3, implanted by Barnard's Star's wind over billions of years. There isn't enough to mine seriously, but prospectors scrape it anyway, and small operators trade it.
• Nickel ore from the green veins, with some cobalt and chromium. Nickel and cobalt are key to reactor and engine alloys, so the waystation can make its own spare parts. Its repair docks are better than you'd expect so far out. The veins also draw independent prospectors, who work claims along the ridges and sell ore to the station.

Why here

• Convenient arrival. A carrier can breach about a million kilometres from the planet, facing out of the system, then reach the waystation with a Level 1 hop of about 10 minutes. Barnard's inner planets are far away and the outer system is clear of debris.
• Everything a carrier needs in one place: propellant, reactor fuel, air, a quiet star, and good position on the route.

The waystation

• Facilities: ice mines and melt plants, a reactor and tritium breeding plant, a nitrogen harvester, repair docks, hitch racks, a customs office, bunkhouses, and a bar.
• Culture: a crossroads. This is where news from different systems meets, and where hitchhikers find their next ride. It's also where deals get made that neither the Alpha Centauri authorities nor anyone else is close enough to watch. A good place for chance meetings, rumours, and trouble.
• Hazards: extreme cold, low light, surface ice that is brittle at these temperatures, and nitrogen frost that turns to gas when warmed by a ship's exhaust or landing lights. The fine grey dust is abrasive and clingy, like lunar dust. It gets into seals, joints and machinery, and landing ships kick up clouds that take a long time to settle in the low gravity and airlessness.