Astronauts began favor the tatooing of their bodies during the second wave of the Space Age.
Astronauts' tattoos have specific meanings:
Swallow: because it always finds the way home and for every AU traveled.
Rooster and pig: on the ankles are to prevent a sailor from drowning. The pig and the rooster: are tattooed on either the calves or the top of the feet, to prevent a sailor from drowning. These animals were originally carried on most ships in wooden crates. When a ship goes down these crates would float and then catch currents and wash ashore with the other debris from the ship, making the pigs and roosters often the only souls to survive a shipwreck. A tattoo of a pig on the left knee: it was a symbol for safety at sea; it was a symbol of protection for sailors. A rooster on the right foot: because it never loses a fight; it symbolizes the fights sailors went while at sea. They were the symbol of fertility; to make sure sailors would always have ham and eggs, and never go hungry.
Ares: it was acquired after you reached Mars.
HOLD and FAST: were tattooed on and across the knuckles.
Anchor: tattoo made by an astronaut that had reached the Earth's moon.
Galileo Class Ship : tattoo made after reaching Jupiter
Two stars: an astronaut who can perform celestial navigation.
Guns or crossed Rail Cannons:
Nautical star or Compass rose: tattoo that symbolize that astronauts always find their way home.
Scythe: tattoo made after reaching Saturn
Cerberus: tattoo made for reaching Pluto and Charon.
Centaur: Often depicted as female, it is made for reaching the Alpha Centaur System.