Overview

Proxima Centauri b, usually referred to as Proxima b, is the only planet orbiting Proxima Centauri, third star in the Alpha Centauri system. It was discovered in 2016 and found to harbor life when video feeds from the first Caravel probes reached the Earth in 2064. It’s a terrestrial planet, 1.3 times the size of the Earth. Roughly half of its surface is covered in sulfuric acid oceans, while its atmosphere is composed of methane, sulfur dioxide, and nitrogen. This is a toxic environment for Earth life, which means that Noah-1 settlers need to wear exosuits capable of resisting these substances to survive Proxima b.

Expansion target

We chose Alpha Centauri as the first human expansion target since it‘s the closest star system to the Sun, located 4.37 light-years away. There are two planets in Alpha Centauri: Alpha Bb orbiting Alpha Centauri B, and Proxima b orbiting Proxima Centauri. Alpha Bb is very close to Alpha Centauri B, with extreme temperatures that melt its surface to lava, making it unsuitable for exploration. Proxima b, despite hotter temperatures than Earth and hostile environment for our biochemistry, is a stable rocky planet which can be explored. Initial probes also confirmed that its crust is relatively rich in osmium, a metal suitable to build materials strong enough to withstand the extreme forces generated by a void gate.

The Sun To Proxima Tunnel (S2PT) Mission aims to create a teleportation tunnel between the Sun and Proxima Centauri. The first phase consists of building a void gate next to Proxima Centauri, allowing unidirectional teleportation from the Vesta Black Hole (located between Mars and Jupiter) directly to Proxima Centauri. The second phase consists of building a void gate next to the Sun and a black hole in Alpha Centauri (target not yet chosen), enabling teleportation from Alpha Centauri to the Sun. After the S2PT is established, we will begin preparation for expansion beyond Alpha Centauri. Probes have already been launched to the Luhman 16 and Epsilon Eridani star systems to determine whether these are suitable for settlement.

Proxima b is 8 times closer to Proxima Centauri than Mercury is to our Sun. If Proxima Centauri were as hot as the Sun, Proxima b would be a molten lava world. When seen from Proxima b’s surface, Proxima Centauri is massive - about 3 times the size of our Sun when viewed from Earth. However, given its fainter light, the brightest areas in Proxima b’s surface are as bright as twilight on Earth. Due to Proxima b’s close orbit, it’s years are also much shorter at about 11 Earth-days.

Proxima b’s tidal locking results in the following hemispheres:

The Day Hemisphere faces Proxima Centauri and is in permanent daylight. Temperatures range from 100°C to extremes of 400°C. The entire ecosystem is supported by photosynthetic organisms at the bottom of the food chain. The South Pole is the southernmost area within the Day Hemisphere. The closest point to Proxima Centauri within a radius of 500km is so hot (reaching temperatures of 400°C) and radioactive that no life forms exist there. For that reason, this area is called the Dead Zone. The Dead Zone also has no oceans, since its high temperatures cause sulfuric acid to evaporate, circulate towards the Night Hemisphere, and condensate into acid rain. Environmental conditions in the Dead Zone are too extreme for standard issue SEV exo-suits, so Noah-1 settlers should avoid it.

The Terminator Line separates the Day Hemisphere from the Night Hemisphere. It has the highest biomass concentration on the planet due to humidity (acid rains are frequent) and optimal temperatures for native life forms to thrive. Like the Day Hemisphere, the Terminator Line’s ecosystem is supported by photosynthetic organisms.

The Night Hemisphere faces away from Proxima Centauri and is in perpetual darkness. Temperatures range from 60°C to -10°C. Despite the lack of light, there is a significant amount of biomass supported by chemosynthetic organisms at the bottom of the food chain. There are no photosynthetic organisms in the Night Hemisphere. The Night Hemisphere is almost always under heavy acid rains, caused by mass evaporation of oceanic sulfuric acid in the Dead Zone and chemosynthetic activity (see biology for details). The North Pole is the northernmost area within the Night Hemisphere. In the farthest regions where temperatures go below sulfuric acid’s melting point, parts of the ocean’s surface are frozen solid.

Life

Proxima b is booming with life, having close to twice as much biomass as Earth. Global biomass is estimated to be roughly half under the oceans and half land-based. Nearly two-thirds of land biomass is concentrated in the Terminator Line, while the other third is spread evenly between the Day and Night Hemispheres. No life has been detected in the Dead Zone.

Biology is completely different from Earth life - lear more here. There is more species diversity in Proxima b than in Earth, driven by tidal locking which allowed the evolution of two diverging ecosystems: one adapted to daylight, supported by photosynthetic organisms at the bottom of the food chain; and another adapted to darkness, supported by chemosynthetic organisms. By contrast, Earth is dominated by photosynthetic organisms that drove other autotrophs either to extinction or to become constrained to niche habitats. 

There is no sign of intelligent life on Proxima b, indicating that evolution is further behind than on Earth. Reasons for this are currently unknown.