Diamond Planets May Lack Oceans

The carbon-rich exoplanets documented by NASA and other space agencies, including the so-called diamond planets, may lack oceans, according to a new study by the space agencies Jet Propulsion Laboratory.

The theoretical research suggests that the diamond planets, which need a carbon-rich sun to form, also lack the icy water reservoir though to supply planets with oceans.

"The building blocks that went into making our oceans are the icy asteroids and comets," said Torrence Johnson of NASA's Jet Propulsion Laboratory in Pasadena, Calif. "If we keep track of these building blocks, we find that planets around carbon-rich stars come up dry," he said.

According to the theoretical research completed by Johnson and his colleagues, which was presented this month at the American Astronomical Society Division of Planetary Sciences meeting in Denver, the extra carbon developing in the star systems would snag the oxygen, preventing it from forming water.

"It's ironic that if carbon, the main element of life, becomes too abundant, it will steal away the oxygen that would have made water, the solvent essential to life as we know it," said Jonathan Lunine of Cornell University, a collaborator on the research.

The research team began by studying planets in the habitable zones of stars. NASA's Kepler mission has found several of these over the years on its quest to find Earth-like worlds.

But even if they found a planet in the so-called Goldilocks zone, where oceans could, in theory, occur, is there actually enough water to available to wet the surface? The answer lies in the carbon-to-oxygen ratio of the planet's sun or suns.

"All rocky planets aren't created equal," said Lunine. "So-called diamond planets the size of Earth, if they exist, will look totally alien to us: lifeless, ocean-less desert worlds."