Stratos

Stratos
	Artist's rending of Stratos
Orbital characteristics
	Epoch A2000
Aphelion	2.54122 AU (380161000 km)
Perihelion	2.32828 AU (348306000 km)
Semi-major axis	2.43475 AU (364233000 km)
Eccentricity	~0.0437290
Orbital period	3.80105227 a (1388.33434 d)
Average orbital speed	19.085 km/s (11.859 mi/s)
Inclination	2.5318°
Satellites	3 natural satellites; 10+ operational artificial satellites
Physical characteristics
Equatorial radius	6248.6 km (3882.7 mi)
Polar radius	6226.2 km (3868.8 mi)
Flattening	.0035972
Circumference	39190.866 km (24352.075 mi) (mean)
Surface area	488,900,000km2; (316,944,000 mi2)
Volume	1.01649 × 1012 km3
Mass	5.42164 × 1024 kg
Mean density	5.3337 g/cm3
Surface gravity	9.300 m/s2
Escape velocity	10.77 km/s (6.69 mi/s)
Sidereal rotation period	1.05123213 d (25.229571 h)
Equatorial rotation velocity	0.43150 km/s (0.26812 mi/s)
Axial tilt	11.71944°
Albedo	0.671 Bond
Atmosphere
Surface pressure	283.710 kPa (at MSL)
Composition by volume	68.1% nitrogen (N2); 27.8% methane (CH4) ; 2.0% argon ; 1.88% other

Stratos is the third planet from Tendor in the Tendor System. Despite its similarity in size and mass with Anteria, it is quite unsuitable for life, hosting an average temperature of below -100 degrees celcius thanks to its high albedo and distance from Tendor, with the frosting on the cake being that its atmosphere has a relatively high concentration of toxic gases in the likes of sulfur dioxide and nitrogen dioxide.

The planet is a terrestrial planet, and is often referred to as Anteria's 'sister planet' due to its similar size and mass, and its landforms, thanks to it having liquid on its surface and having a thick atmosphere, is surprisingly similar to Anteria's. It is one of the brighter objects in the night sky thanks to its high albedo caused by its icy surface of frozen carbon dioxide (dry ice), solid hydrocarbons, and water ice. It appears slightly blue-green thanks to the high amount of copper present in the planet's crust, forming a large amount of copper salts and oxides of the color that mixes with the other constituents of its surface. Lakes and seas of light hydrocarbons are present on the surface of the planet, though it likely does not host any extraterrestrial life.

Despite its inhospitability, it is still one of the more prominent celestial bodies that Anterians wish to colonize within the near future thanks to its relative proximity, though it is quite likely that colonies would instead be constructed on one of its two substantial moons first, being easier to use as stepping stones for further exploration than Stratos, having an atmosphere over two and a half times thicker than on Anteria.

Physical Characteristics

Stratos is one of the four terrestrial planets in the Tendor system, hosting a surprising amount of interesting geography for a supposed frozen ice ball, due to its thick atmosphere allowing for liquid to exist on its surface.

Geography

Stratoshian geography is surprisingly familiar thanks to the presence of liquid C₂-C₅ hydrocarbons on the surface, and hosts the same sort of geography one sees on Anteria, including river valleys, floodplains, and in certain locations even mesas. The main difference (ignoring the obvious lack of life) is that there are only a handful of shallow seas and lakes, meaning that there are regions that receive little to no precipitation, creating large swaths of barren desert, which much more resembles what scientists would expect on a frozen planet of the sort, similar to the planet Mars in the fictional system of Sol.

Surface Geology

The Stratoshian surface appears to have been shaped primarily by various forms of weathering, plate tectonics, and volcanic activity, with little to no signs of asteroid impact, while it is formed primarily of volcanic rock in the likes of basalt, andesite, and granite, with a high concentration of copper and nickel, contributing to the planet's blue-green tint. WIP

Hydrology

Due to its extreme temperatures, liquid water does not exist on the Stratoshian surface besides in the vicinity of active volcanoes/geothermal vents, and only in small amounts even there. On the other hand, as previously stated, liquid light hydrocarbons do exist in fair abundance on the surface of Stratos, allowing for familiar weather phenomena to take place. In more extreme latitudes, due to the fact that solid hydrocarbons are more dense than its liquid form, rivers and lakes tend to change shape throughout the year, and in certain cases may even be entirely rerouted in a span as short as a few days. This phenomena has contributed quite heavily to the existence of enormous river valleys and deltas that dot the surface, of which many are quite easy to see with a decent telescope.

Orbit and Rotation

Stratos's average distance from the Sun is roughly of 364 million kilometers (226 million miles) and its orbital period is 1388 (Anterian) days. The solar day (or sol) on Stratos is slightly longer than the solar day on Anteria, lasting 25 hours, 13 minutes and 46.32 seconds. The axial tilt of Stratos is of 11.72°, which means that Stratos has seasons that aren't very marked, unlike Anteria's. Stratos has moderate orbital excentricity, of about 0.0437, which is similar to Tsanfau's excentricity.

Stratos approaches Anteria every 495.62 days.

Moons

Loftuslo

Loftuslo, or Stratos I, is the closest moon to Stratos, and is thought to have been created from a collision between Stratos and a large planetoid, similar to that of the Anterian Moon, and is hence created with similar material, giving it a slight blue-green tint like that of Stratos, though unlike Stratos, it has no atmosphere and is mostly just a barren, frozen rock.

Despite it being much less interesting than Stratos itself, its low gravity and lack of atmosphere makes it a prime target for a forward operating base for colonizers, and a good place to extract resources, though effects of its low gravity long-term is still unknown.

Kurato

Kurato, or Stratos II, is the further of the two substantial Stratoshian moons, and seems to have been a captured planetoid. The moon is larger than Loftuslo, and would serve as a good location for the first base outside of the Anteria-Moon system.

Dapuriyo

Dapuriyo, or Stratos III, is a captured asteroid that currently orbits Stratos at about half a million kilometers above its surface. It is slowly but surely drifting away from Stratos.

Habitability

Stratos in its current state is fairly inhospitable to life, and will take a large amount of terraforming to make the entire planet habitable for humans, if that is at all possible, though it is speculated that there may be Stratoshian microbes in certain volcanic hotspots acround the planet, given that liquid water have been observed to be present on the surface near volcanic vents, though if they do exist, likely only in small numbers.

Stratos would tough to colonize effectively, thanks to its thick atmosphere and similar gravity to Anteria making leaving the planet require more fuel than leaving Anteria itself, though not to say it is entirely unfeasible. For starters, water ice is fairly common on Stratos, albeit requiring a bit of excavation to get to, allowing for the creation of breathable oxygen, and possibly fuel as well in the form of hydrogen. The surface gravity is practically the same as on Anteria, and there are plenty of exploitable resources on the surface of the planet. The main hurdle as of the time being is actually making it to Stratos without receiving a lethal dose of cosmic radiation, and to set up a base to begin with. In the grand scheme of things, despite the abundance of fuel and resources on Stratos itself, it is likely more practical to set up camp on one of its significant moons to start instead, before moving onto the planet itself.