Peanut-shaped asteroid could hold clues to Earth's water source.
Salt crystals have been found in a sample of asteroid Itokawa, which was returned to Earth by Japan's Hayabusa mission in 2010. The sodium chloride crystals, which could only have formed in the presence of water, were discovered in the asteroid's sample, implying that the largest body of space rocks in the solar system may be richer in water than previously thought. The finding suggests that most, if not all, of Earth's water arrived via asteroid bombardment during the planet's violent early history.