If large impacts ceased early in Mars’ history, that would leave plenty of time for life to have formed in its ancient oceans. (Credit: NASA/GSFC)

When the solar system was young, some scientists suspect it was too wild and raucous a place for life to develop. Earth, Mars, and the other planets were all being pelted by massive asteroids and rocky debris. Some of those rocks might have delivered the very water that later made life possible. But the unrelenting impacts may have made the surfac