Lighter-toned bedrock that surrounds fractures and comprises high concentrations of silica — called “halos” — has been found in Gale crater on Mars, indicating that the planet had liquid water much longer than previously believed.
Lighter-toned bedrock that surrounds fractures and comprises high concentrations of silica — called “halos” — has been found in Gale crater on Mars, indicating that the planet had liquid water much longer than previously believed.