NASA’s Perseverance rover revealed evidence of an ancient beach on Mars.
The rover spent nearly a year exploring the rim of a crater believed to have held a huge lake; the rocks show signs of having been shaped and altered by waves, creating a sandy layer. Shorelines on Earth are key sites for life, and also for creating fossils; the discovery provides an excellent place to search for evidence of past biology.
It also extends the period during which liquid water existed on Mars. A separate study using satellite data found that a huge ocean in northern Mars was larger and deeper than previously believed — about as large as the Arctic Ocean — and identified huge river deltas emptying into it.