Squyres went on to caution that there is no evidence of life in Homestake today, but "the watery conditions that would have been necessary - the requirement of water being there - was present."
Turning on the Tap
The international team also examined rocky outcroppings sent flying when a second impact formed the smaller Odyssey crater. Only 62 by 75 feet (19 by 23 meters), the elliptical crater rests on the rim of Endeavour.
Opportunity studied an outcropping known as Tisdale, and found it contained zinc, a chemical element often associated with hydrothermal activity.
"If you go to zinc mines on Earth, they're generally in places where hydrothermal processes have deposited zinc," Squyres said.
Such places tend to be near volcanic activity, or other processes in the crust that heat the water around it.
On Mars, the movement of hot water was likely jumpstarted by the blow from the rock that formed Odyssey.
"A crater that size involves a lot of energy," Squyres said.
When the large body gashed the surface of the Red Planet, it likely heated water already contained within the crust or at the surface.