Lab Report

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The Lab Report is a weekly compendium of media reports on science and technology achievements at Lawrence Livermore National Laboratory. Though the Laboratory reviews items for overall accuracy, the reporting organizations are responsible for the content in the links below.

Feb. 19, 2021

covid mutation

In SARS-CoV-2, the RNA virus that causes COVID-19, multiple variants can exist simultaneously in a mutant cloud.

The varying ways of viruses

Scientists say they’re hearing from members of the public who worry that the virus that causes COVID-19 will evolve resistance to the vaccines against it.

Viruses, like bacteria, are constantly mutating. Considering that more than 2 million people a year in the U.S. are sickened by bacteria that have developed resistance to the first line of antibiotic defense, it stands to reason that viruses could likewise defeat the vaccines being deployed against them.

One worrisome feature of RNA viruses such as SARS-CoV-2 is that multiple variants can exist simultaneously in a host cell in what’s called a mutant cloud, a mutant swarm or a quasi-species. While one variant is dominant, it’s important to understand the subdominant variants as well — just as a baseball coach wants to know what pitchers are warming up in the bullpen, says Monica Borucki, a microbiologist at Lawrence Livermore National Laboratory.

Squeezing down the number of infections through vaccinations will reduce the number of mutations, which in turn will lower the risk of dangerous new variants, Borucki said.

asteroid

Kirsten Howley, a Lawrence Livermore National Laboratory researcher, has a game plan for dealing with the potential danger of an asteroid hurtling toward Earth

Getting it wrong and right

Life isn't always like the movies.

Not that an asteroid couldn't slam into Earth, like in the movie “Armageddon.” Asteroids — mostly tiny ones — pass by our planet virtually every second. But the people charged with stopping the big ones aren't reaching for their spacesuits with mere hours to spare.

“I would say the number one question I get when I tell people what I work on is 'Oh, like ‘Armageddon?’ And it's nothing like ‘Armageddon,’” says Lawrence Livermore National Laboratory physicist Kirsten Howley, whose day job includes defending our planet from asteroids.

Howley doesn't have an orange jumpsuit at hand, but her job is serious business. She and her team of planetary defenders specialize in how we might deflect an asteroid that poses a threat to Earth, like Bennu —- an ancient asteroid currently orbiting the sun on a path that brings it close to Earth. It has a 1-in-2,700 chance of colliding, albeit not until 2185.

rocky planet

An artistic rendering of the interior structure of Earth (left) compared to a large rocky exoplanet (right). Image by John Jett and Federica Coppari/LLNL.

Rock on

Learning more about the interior of rocky planets like Earth could provide important clues about their potential habitability.

Led by Lawrence Livermore, a team of researchers aims to unlock some of these secrets by understanding the properties of iron oxide — one of the constituents of Earth's mantle — at the extreme pressures and temperatures that are likely found in the interiors of these large rocky extrasolar planets.

“Because of the limited amount of data available, the majority of interior structure models for rocky exoplanets assume a scaled-up version of the Earth, consisting of an iron core, surrounded by a mantle dominated by silicates and oxides. However, this approach largely neglects the different properties the constituent materials may have at pressures exceeding those existing inside the Earth,” said Federica Coppari, a Lawrence Livermore physicist and lead author on the study. “With the ever-increasing number of confirmed exoplanets, including those believed to be rocky in nature, it is critical to gain a better understanding of how their planetary building blocks behave deep inside such bodies.”

Using giant lasers at the University of Rochester's Omega Laser Facility, the researchers squeezed an iron oxide sample to nearly 7 megabars (or Mbar — 7 million times the Earth's atmospheric pressure), conditions expected in the interiors of rocky exoplanets approximately five times more massive than Earth. They blasted additional lasers at a small metal foil to create a brief pulse of X-rays, bright enough to enable them to capture an X-ray diffraction snapshot of the compressed sample.

explosives

The first-ever shot with explosives was recently conducted at the National Ignition Facility.

It’s explosive

The first-ever shot to study a high explosive sample was recently conducted at the National Ignition Facility, the world’s most energetic laser.

The results from the shot included novel data that will help researchers unlock the mysteries of high-explosive (HE) chemistry and position Lawrence Livermore National Laboratory to continue its legacy as a leader in HE science and diagnostic innovation.

“This shot is the first in a series that will transform the Lab’s understanding of high explosives by producing never-before-captured experimental data quantifying the response of laser-driven high explosives during reaction,” said Lara Leininger, director of LLNL’s Energetic Materials Center and lead for this Laboratory Directed Research and Development project.

The results also allow LLNL to critically evaluate predictive computational capabilities and the Lab’s world-class thermochemical code, Cheetah, and greatly expand experimental capabilities being applied in high explosives, Leininger said.

heat

LLNL scientists are conducting experiments to better understand rocky-type planetary materials’ high temperature and pressure behavior, which is key to developing better models of Earth and other terrestrial exoplanets.

It’s shockingly hot in here

Temperature is tough to measure, especially in shock compression experiments. A big challenge is having to account for thermal transport — the flow of energy in the form of heat.

To better understand this challenge, researchers from Lawrence Livermore have taken important steps to show that thermal conduction is important and measurable at high pressure and temperature conditions in these types of experiments.

“We need better temperature measurements because understanding rocky-type planetary materials’ high temperature and pressure behavior is key to developing better models of Earth and other terrestrial exoplanets,” said David Brantley, LLNL physicist and research lead.

Brantley said that depending on how iron conducts heat at Earth's core pressure and temperatures, the planet's solid inner core could be around 500 million to several billion years old.