Martian soil perchlorate readings being caused by terrestrial sources, which at the time were thought could have migrated from the spacecraft either into samples or the instrumentation. However, each new lander has confirmed their presence in the soil locally and the "Mars Odyssey" orbiter confirmed they are spread globally across the entire surface of the planet. While our understanding of Martian soils is extremely rudimentary, their diversity may raise the question of how we might compare them with our Earth-based soils. Applying an Earth-based system is largely debatable but a simple option is to distinguish the (largely) biotic Earth from the abiotic
Solar 2 with asteroids, planets, stars and solar systems. Life forms are also present in the game. They appear on planets sufficiently big to store life, and are represented by a variety of ships of different size and attack power. Spaceships are coloured green if they belong to the player's planet, or to a planet that belongs to the player's solar system; red if they belong to an enemy planet or solar system; and white if they don't belong to any planet or system. All the spaceships in the map are controlled by the game's artificial intelligence (AI), and they will constantly