The Laboratory in the News

Water Signature Revealed in Extrasolar Planet

Laboratory astrophysicist Bruce Macintosh, along with a team of international scientists, has made the most detailed examination yet of a Jupiter-size planet’s atmosphere beyond our solar system. Using the OSIRIS instrument on the Keck II telescope in Hawaii, the team has uncovered the chemical fingerprints of specific molecules, revealing a cloudy atmosphere containing water vapor and carbon monoxide. “With this level of detail,” says Travis Barman, an astronomer at Lowell Observatory in Arizona, “we can compare the amount of carbon to the amount of oxygen present in the atmosphere, and this chemical mix provides clues as to how the planetary system formed.”

The planet is one of four gas giants known to orbit a star called HR 8799, 130 light-years from Earth. Although the planet’s atmosphere shows clear evidence of water vapor, that signature is weaker than would be expected if the planet shared the composition of its parent star. Instead, the planet has a high ratio of carbon to oxygen—a fingerprint of its formation in a gaseous disk tens of millions of years ago.

As the gas cooled with time, grains of water ice formed, depleting the remaining gas of oxygen. Planetary formation began when ice and solids collected into planetary cores—similar to how our solar system formed. “This spectrum is the sharpest ever obtained of an extrasolar planet,” says Macintosh. “The exquisite resolution afforded by these new observations has allowed us to begin to probe the planet’s formation.” The team’s findings appeared in the March 22, 2013, edition of Science.

Scientists Find New Materials to Capture Methane

Scientists at Lawrence Livermore and the University of California at Berkeley have discovered new materials to capture methane, the second highest concentration greenhouse gas in our atmosphere. Methane is a substantial driver of global climate change, contributing 30 percent of today’s net warming. Concern of methane is mounting because of leaks associated with rapidly expanding unconventional oil and gas extraction. In addition, as Arctic ice cover continues to melt, the potential exists for large-scale release of methane from decayed material. At the same time, methane is a growing source of energy.

The research team, which includes Livermore’s Amitesh Maiti, Roger Aines, and Josh Stolaroff, performed computer simulation studies on the effectiveness of methane capture using two different materials—liquid solvents and nanoporous zeolites. Zeolites are unique structures that can be adapted for many types of gas separation and storage applications because of their diverse topology. The porous materials are commonly used as commercial adsorbents.

While the liquid solvents were not effective for methane capture, a systematic screening of about 100,000 zeolite structures uncovered a few nanoporous candidates that appear technologically promising. In the team’s simulations, one specific zeolite, dubbed SBN, captured enough medium-source methane to convert it to high-purity methane, which in turn could be used to generate efficient electricity. The team’s research was reported in the April 16, 2013, edition of Nature Communications.

Moon’s Core Active Later Than Thought

New evidence from ancient lunar rocks suggests that the Moon’s long-lived dynamo—a molten, convecting core of liquid metal that generated a strong magnetic field—lasted 160 million years longer than originally estimated. Lawrence Livermore scientist William Cassata and a group of international collaborators analyzed two rocks gathered during the Apollo 11 mission and found that the samples were magnetized in a stable and surprisingly intense magnetic field. The study of these slowly cooled, unshocked rocks demonstrates that the Moon had a core dynamo as late as 3.55 billion years ago.

“The Moon possessed a magnetic field much later than would be expected for a body of its size,” says Cassata. The study shows that the Moon likely possessed a long-lived core dynamo, much like the one that currently exists on Earth, but generated by a different mechanism. Earth’s core dynamo is generated by thermally driven convective motions in the liquid outer core. However, because of its size, the Moon was too cool to sustain core convection as late as 3.55 billion years ago.

In the past, however, when the Moon was closer to Earth, its greater angle of precession would allow for mechanical stirring of the liquid metal core by the overlying rocky mantle. These motions can induce a global magnetic field. A gradual decrease in the Moon’s precession angle as it moved further away from Earth and an increase in its core viscosity as it cooled may have caused the dynamo to decline between 1.8 and 2.7 billion years ago. According to Cassata, “The lifetime of the ancient lunar core dynamo has implications for mechanisms of field generation on other planetary bodies.” The research appeared in the May 6, 2013, edition of Proceedings of the National Academy of Sciences.