Lore: the world of Reaction Mass

The world in brief

Some 5 million people live in hollowed rock, split among hundreds of rival city-states. Water is power, every journey has a cost, and the frontier is opening for the first time.

On the surface, human factions compete for water, rock and legitimacy as new charters are granted for the outer belt. Underneath, something older is waiting in the frontier ice.

Spoiler: what lies underneath

The frontier rock carries dormant life from the Interloper's shattered moons. Human warmth wakes it, and the first colony to wake it fully sets the whole belt on a new course.

The name

Reaction mass is what a ship throws out behind it in order to move. In the belt it is usually ice, the same ice people drink and breathe, so every journey spends something someone could have lived on.

The phrase runs through the whole setting. The Exodus was flung across space by mass drivers. Hollowers use it as slang for people who get spent so that others can move: "We're just mass to them" is a complaint anyone in the belt understands.

Spoiler: two more meanings

The Interloper itself stayed in our system by throwing away its own moons, including the home of the life now sleeping in the frontier ice.

It also reads as the reaction of the masses: a population pushed too far, and an alien species reacting to humanity's warmth.

Everything that moves, something is spent.

What the story is about

Nothing is free: Every litre, ingot and person is moved physically, at a cost in time and delta-v. Energy is scarce, and how you spend it is a moral question as well as a practical one.
Survivor's inheritance: Billions were left behind. The survivors' descendants carry that guilt, the class lines drawn by who got a berth, and the relics of a world they never saw.
Always awake, or knowing when to sleep: Humans burn constantly and endure. The life in the ice bursts into activity and then goes dormant. Each side comes to think the other's way of living is a sickness, and each has a point.
Nobody is native: Everyone in the belt is a refugee in rubble that belongs to no one.

Explore the lore

History

The Interloper, the Exodus, the Conjunction, and 150 years of survival in the rock, from the Lean Years to the opening of the frontier.

Read the history

The belt

Life in 2251: the old belt and the frontier, the homeworld debris field, the Solar Web, and why water is power.

Visit the belt

Factions

Six great blocs of city-states, their rival sub-factions, the independent cities, and the fault lines between them.

Meet the factions

The rime

A strange rot in frontier rock, and the life that has been asleep in the ice for 150 years. Mostly spoilers.

Into the ice

About spoilers

Anything a belter would know in 2251 is always shown. Anything the game reveals through play is hidden in panels like the ones above.

Open a single panel to read it, or use the Spoilers switch at the top of the page to show or hide every spoiler at once. Your choice is remembered on this device as you move between lore pages.

Glossary

AC: After the Conjunction. Hollowers count years from 2101, when Mars struck Earth, so 2251 is 150 AC.
Air right: The oldest law of the Scatter: anyone who asks for air is given it, enemy or not.
Berth lines: Exodus berths were split between skills, a public lottery and berths sold by the Charter Companies. Six generations on, families still call themselves skill-born, lottery-born or Charter-born.
The Conjunction: The collision of Mars and Earth in 2101, which destroyed both worlds.
Conjunction Day: Observed every year: lights are dimmed for an hour, and the names of home towns are read out.
Daughter colony: A settlement founded by a splinter group from a crowded city: independent, but bound to its mother city by kinship, memory and old grudges.
The Ember: What Hollowers born since the Conjunction call the Interloper, for the dull red point it makes in the sky.
The frontier: The outer belt and the high-inclination orbits where the Interloper's debris lies. Rich in ice, almost unclaimed, and hard to reach.
Gravers: Salvagers who work the homeworld debris field for Earth relics, soil, ruins and archives.
Hollowers: The people of the belt, who live inside hollowed rock.
The Interloper: The cold brown dwarf, catalogued as DSO-1, that passed through the inner solar system in 2094.
Lamplighters: The relay guild that maintains the Solar Web.
The Left Behind: The billions who never reached the belt. "You'd have left them behind" is a deadly insult.
The Moot: The gathering of the Red Clans, held once every Martian year.
The old belt: The inner and middle belt, settled during the Exodus. Crowded, claimed and short of water.
The Old Paper: Exodus-era berth debts, passed down through families. Some people are still bonded to pay them off.
Reaction mass: What a ship throws out to move, usually ice. Also slang for people who get spent so that others can move.
The Return: The Interloper's next closest approach, around 2325.
The rot: Grey-green staining that prospectors find in some frontier rock and ice. Usually taken for a mineral stain.
Sols: Martian days, still used by the Red Clans to keep time.
The Solar Web: The relay network that ties the belt together, carrying messages, news, the job market and the ledger behind the belt's money.

Spoiler: terms you'll learn later

Bloom: The stage at which the rime fruits into intelligent individuals, and the season in which they are active.
Brood: A separate population of the aliens, with its own wake cycle, inherited memories and outlook. Humans number them in the order they wake.
The Changed: People slowly altered by medicine made from rime biomass.
Hearth: The largest of the Interloper's moons, home to the life now sleeping in the frontier ice.
Long Sleep: The aliens' dormancy between warm seasons.
Rime: The active, frost-like growth of the alien life, spreading through warm, wet rock.
Torpor: Human dormancy technology adapted from rime biology.
The Waking: The spread of the reawakened rime along human trade routes, outward from the first colony to wake it.
Wane: The end of a Bloom, when the individuals withdraw into the rime.