The kit of those who work off a planet
El Lastre
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El Lastre is the kit settlers carry when they work off a planet, on the moons and on the asteroid Ashkar, where gravity is low. They came up with it themselves: a ballast vest, a grip thruster and anchors with a lifeline. Gravity on each body is just what its size and density call for: the mystery lies in the orbits.
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Aurin’s gravity is that of its bodies.
What is El Lastre?
El Lastre is the kit carried by every settler who works off a planet. It is equipment, not a force or an anomaly, and it was the settlers’ own idea. It has three pieces:
- The ballast vest. This is the first piece, and the one that gives the whole kit its name.
- The grip thruster.
- The anchors with a lifeline.
How much does each body in Aurin pull?
Aurin’s gravity is that of its bodies. Every planet, moon or asteroid around Aurin, the system’s star, pulls exactly what its radius and density dictate. No more, no less.
| Body | What it is | Gravity (m/s²) |
|---|---|---|
| Kaldrek | Planet | 10.2 |
| Ithera | Planet | 9.23 |
| Kharsis | Planet | 8.98 |
| Ormek | Planet | 8.88 |
| Melvara | Moon of Ithera | 1.91 |
| Tirane | Moon of Ithera | 1.38 |
| Kravane | Moon of Kharsis | 1.06 |
| Erran | Moon of Kharsis | 0.87 |
| Kharun | Moon of Kharsis | 0.70 |
| Ordrek | Moon of Kaldrek | 0.69 |
| Selvane | Moon of Ithera | 0.42 |
| Cinera | Moon of Ormek | 0.40 |
| Pyra | Moon of Ormek | 0.39 |
| Renvar | Moon of Kaldrek | 0.21 |
| Ashkar | Captured asteroid of Kharsis | 0.034 |
The figures fall into two bands set far apart:
- On the planets, gravity runs from 8.88 m/s² on Ormek to 10.2 on Kaldrek.
- On the moons, it runs from 0.21 on Renvar to 1.91 on Melvara.
- Ashkar, the asteroid, sits at 0.034.
The gap between the extremes is huge: Kaldrek pulls 10.2, three hundred times as much as Ashkar. In between sit the other three planets and Aurin’s ten moons.
Who measured it?
First came an estimate. In Year 0 E.A. (E.A. stands for Años de Asentamiento, the settlers’ calendar), the Registro Aura catalogued the system from afar. It was the first catalogue of Aurin, made with telescopes and mass models before setting down anywhere. It put Ithera at 0.94 g and Ashkar at 0.03 m/s². Both figures were good.
Then came the measurement. The engineers of the Flota Aura, the fleet that brought the settlers, took it. The dossier on the Aurin system dispatches it in a line:
“The engineers of the Flota Aura measured it on arrival, and what they measured matched their mass models: there was no anomaly.”
Dossier on the Aurin system
The Flota’s old manuals gave other gravities for these bodies. They have been withdrawn. The archive records only the physics of each one.
What is still unexplained?
The mystery is not the gravity but the orbital clock. The three schools of scholars that argue over the system accept the gravity. What no one can explain is the motion.
- The moons complete their orbits in hours, where the measured masses call for days.
- Selvane goes round Ithera in two hours. Given its mass and distance, it should take almost a month.
- Melvara does it in half an hour.
- Even so, within each family of moons, the relationship between distance and period is as exact as clockwork.
That is why no one in Aurin works out trajectories from masses. They consult the Tabla de Fases, which records the orbits as they are observed. The Pathfinders, the explorers’ guild, measure it body by body. It fits into three words: measured, not derived.
