For astronomers seeking clues to the origins of life, it's a sweet find.

Scientists have discovered sugar in meteorites that fell to Earth from outer space, filling a hole in the theory that such space rocks may have spurred the development of life by delivering the necessary chemical building blocks.

The findings, published today in the journal Nature, conclude that sugars found in two meteorites that fell to Earth in 1950 and 1969 were not contaminants that came to the rocks after impact.

Because the meteorites were formed about 4.5 billion years ago during the early history of the solar system, and they have avoided being recycled by planets, they are essentially well-preserved museums for scientists studying what conditions were like at those times, and what materials made up the planets.

Sugars and related compounds, known as polyols, are critical to life as we know it because they are components of DNA and cell membranes and provide a source of energy.

"One conclusion from our work is that polyols were present on the early Earth and, at the least, available for incorporation into the first forms of life," said the study's lead author, George Cooper, a scientist at NASA's Ames Research Center.

Since the early 1960s scientists have thought carbon-heavy meteorites, and possibly comets, kick-started life on Earth by providing raw organic materials.

"Until now, though, the organic mixtures in (meteorites) were missing one obvious ingredient from the recipe of life: sugars," wrote astronomer Mark Sephton of the British Planetary and Space Sciences Research Institute in a Nature article analyzing the discovery.

One expert on the origin of life, San Diego State University marine chemistry professor Jeffrey Bada, said the findings were quite interesting, even tantalizing, but cautioned that sugar in two meteorites does not come close to answering the question of how the first life formed.

The authors acknowledge that many questions about the chemistry of life's origins remain.

However, because meteorites are the only direct evidence scientists have of early important biological compounds, the absence of sugar in prior samples had left major gaps in the understanding of the chemistry of early organisms.

The scientists found that the types of sugar compounds in the meteorites, based upon their chemistry, were characteristic of material found in space.

Cooper and other scientists believe the sugar compounds may have formed as starlight heated icy water, ammonia and carbon monoxide on the surface of small dust particles.