This page is about the planet. For the Roman deity, see Mercury (Mythology). For the silvery metal, see Mercury (element). For the possibly-fictional WMD component, see Red Mercury.

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Basic Information

The closest planet to the Sun, Mercury is also the smallest (now that Pluto has been demoted to dwarf planet). Mercury is much denser than other objects (such as moons) of its size, probably because of a very large planetary core composed of iron. Mercury is a Terrestrial Planet.

Mercury is about 4880 kilometers (3000 miles) in diameter. In a spacefaring campaign, it may be useful to know that Mercury's escape velocity is 4.25 kilometers per second (2.65 miles per second), somewhat more than a third of Earth's.

Due to its position in the Sun's gravity well, Mercury is harder to reach than its distance would suggest. Given the great mineral wealth (seriously, so much iron), it's likely that humanity of the far future will want to make use of the planet despite this difficulty. The asteroid belt might have enough resources for us for a long while, but if we want to try a particularly ambitious Stellar Megastructure, we'll need to figure out how to mine Mercury, most likely with robots. Mercury's escape velocity is low, so once minerals are extracted, it'll be easy enough to get them off the planet, especially if the goal is making something like a Dyson Swarm, where proximity to the big solar fireball is actually a blessing.

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Game and Story Use

  • Scientific stations to study the Sun could be placed on Mercury.
  • Some sort of grey goo or robot uprising scenario could start on Mercury due to a replication error in a robotic factory that's part of the process assembling a Dyson Sphere. Aside from the usual dangers of robots-gone-wild, you'd also have the risk that the bots might (intentionally?) block all sunlight from reaching the earth. Fighting back against the threat would mean undoing the work of a stellar megastructure that perhaps had become the main focus of our entire species. If the robots show no sign of trying to extend beyond Mercury and the D-Sphere, it might actually be decided that the best bet is to just quarantine the small uninhabitable planet and let the robots complete their mission of harnessing all the sun's power for us… but that gamble is a Sword of Damocles dangling over everyone. What will the uncontrolled robots do if they finish their primary mission, or evolve beyond it?
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