Sugar formation, as with much of the complex molecular chemistry in space, occurs in the solid phase on or in a variety of ices that coat interstellar grains. Most land-based chemistry occurs in the liquid phase, primarily with water, thus the widely accepted theory that life on Earth began in a "primordial soup." While these two chemistry scenarios are very different, the end results can be very similar. The possibility of early impacts from comets bringing both the water supply and the sugars and other compounds that are life's building blocks to the Earth's surface has been a scientific theory for years. Once those sugars were free from their interstellar freezer and were steeped in the Earth's warm waters, they could have easily combined with other carbon compounds and eventually formed RNA and DNA.