Colonization of the outer Solar System the Solar System's gas giant planets for exploration and possibly mining of helium-3, which could have a very high value per unit mass as a thermonuclear fuel. The Jovian system in general has particular disadvantages for colonization, including its severe radiation environment and its particularly deep gravity well. Its radiation would deliver about 3,600 rems per day to unshielded colonists on Io and about 540 rems per day to unshielded colonists on Europa. Exposure to about 75 rems over a few days is enough to cause radiation poisoning, and about 500 rems over a few days is fatal. Jupiter itself,
Formation and evolution of the Solar System could be affected by these events, the Sun and planets are not expected to be disturbed. However, over time, the cumulative probability of a chance encounter with a star increases, and disruption of the planets becomes all but inevitable. Assuming that the Big Crunch or Big Rip scenarios for the end of the Universe do not occur, calculations suggest that the gravity of passing stars will have completely stripped the dead Sun of its remaining planets within 1 quadrillion (10) years. This point marks the end of the Solar System. Although the Sun and planets may survive, the Solar System,