Researchers: Mars had water 3 billion years ago. This dispute has raged for decades. New study narrows the gap.

Chinese researchers suggest that the location where the Zhurong vehicle formed was more humid for at least two billion years based on “water’s imprint” in a rock. Researchers used the laser on Zhurong in Utopia Planitia. 11-May Science Advances released their study.

Finding subsurface water requires knowing when Mars had surface water. Provide indices to estimate remaining ice.

The European Mars Express spacecraft allegedly identified a lake 1.5 km below the surface. Another team says they are volcanic rock data. Debate continues.