For astronomers, probing the mysteries of “space ice”—its molecular makeup and how it formed—could be the key to understanding not just extraterrestrial geology but also the potential for alien life.

Visual representation of the structure of low-density amorphous ice. Many tiny crystallites (white) are concealed in the amorphous material (blue). “Space ice” contains tiny crystals and is not, as ...

Water frozen in the depths of space has long been considered a shapeless, frozen fog. For decades, scientists believed it formed without structure, too cold and still to grow orderly crystals. But a ...