Melvara

What is Melvara like?

Melvara goes round Ithera, the temperate planet of the system. It is the largest of the ten moons of Aurin, the star, and the only one with breathable air.

• Size. 1,950 km in radius.
• Gravity. 1.91 m/s², a fifth of Ithera’s.
• Air. Breathable: 72 kPa with 27% oxygen. That is less pressure than on Ithera and more oxygen, like breathing at about 750 m.
• Landscape. Sea and islands, with life.
• From orbit. Its blue edge looks wide for so small a moon. But its air doesn’t reach as high as Ithera’s: 26 km, against 80.

Where is it, and who holds it?

Melvara is the closest of Ithera’s three moons. In Ithera’s sky it is simply “the moon”. It is the disc that crosses the whole sky in under twenty minutes and tints the wetlands a greenish grey. It appears on the emblems of three of the 5 Global Guilds, five trade organisations that take no side.

There are three installations, and all three call themselves civilian:

• Observatorio Cumbre, held by the Zenith, one of the system’s two sides.
• Casa de Piedra, held by the Nadir, the other side. It sits in the hollow of an ochre mesa (a flat-topped hill) of some six hundred metres. It lies below the rim, without losing the view of Ithera that justifies the site.
• El Fiel, held by the five Guilds. The dossier on the moons of Aurin describes it:

“Between them, exactly between them, the five Guilds built El Fiel: an inspection station with its doors always open whose only job is to count what goes in.”

Dossier on the moons of Aurin

The observatory and the Casa de Piedra are four hundred kilometres apart. On a moon this size, the horizon hides each installation from the others. Their only link is a radio marker at each, and they watch each other by radio. Neither has ever fired.

Why do lawyers argue about Melvara?

The Registro Aura, the first catalogue of the system, entered Melvara as a world. When it found the body was going round Ithera, it crossed the record out by hand. That crossing-out is now the most expensive legal argument in the system.

The Armisticio de Ithera, the treaty that stopped the war between the two sides, forbids militarising Ithera’s orbit. Melvara is in that orbit. But it is also a body 1,950 km in radius, with a horizon, geology and ground underfoot.

In thirty-five years, no lawyer on either side has persuaded the other to accept that this counts as “orbit”. So both have done the same thing: “strictly civilian” installations, with “strictly civilian” staff. The sites were chosen for their scientific value: the view of Ithera and the clear sky.

On Melvara everyone goes armed, but disputes are settled by the inspection.

What is the land like?

Beneath the treaty lies a moon older than any treaty.

• A slate mountain range robs half a continent of its rain.
• Behind it lies a desert of canyons, the bed of a fossil inland sea: red sandstone stacked up over eras. It covers 39% of the moon’s land.
• The rest is granite with limestone platforms.
• Near the coast there are minor volcanoes, island cones that leave black sand on the beaches.

Why does it not lose its air?

Its escape velocity, the speed needed to get away from its gravity, is 2.7 km/s. At that, air like this would leak away over geological time. Three things hold it:

• A cold upper layer. The thermosphere, the top of the air, is cooled by CO₂ and sea vapour giving off heat as radiation.
• Ithera’s shield. Ithera’s magnetosphere, its magnetic shield, protects Melvara from part of Aurin’s wind, the particles the star gives off.
• Life. The sea and the islands top up the oxygen every day, and the volcanic cones on the coast return nitrogen and CO₂.

What is odd about its orbit?

Melvara goes round Ithera in half an hour. With Tirane and Selvane, Ithera’s other two moons, it heads a 1:2:4 Laplace chain. Tirane takes exactly twice as long as Melvara, and Selvane twice as long as Tirane, down to the last digit. Because of their phase, the three never line up at once.

That orbit is not worked out from the masses: it is looked up in the Tabla de Fases, the system’s table of measured orbits. The moons move faster than their masses say they should, and no one knows why.