UCLA study overcomes effects of Earth’s gravity and replicates conditions on other planets, stars – Zoo House News
Solar flares and other types of space weather can have devastating effects on space travel and telecommunications and other types of satellites orbiting the Earth. But to date, scientists’ ability to explore ways to overcome this challenge has been severely limited. That’s because experiments they run in labs here on Earth are affected by gravity in very different ways than conditions in space.
But a new study by UCLA physicists could finally help solve this problem – which could be a big step towards protecting people (and equipment) during space expeditions and ensuring satellites are functioning properly. The paper is published in Physical Review Letters.
The UCLA researchers effectively reproduced the type of gravity that exists on or near stars and other planets within a glass sphere 3 centimeters (about 1.2 inches) in diameter. To do this, they used sound waves to create a spherical gravitational field and create plasma convection — a process in which gas cools as it approaches a body’s surface, and then reheats and rises again as it approaches the core – which creates a liquid current, which in turn creates a magnetic current.
The achievement could help scientists overcome the limiting role of gravity in experiments aimed at modeling the convection that occurs in stars and other planets.
“People were so interested in modeling spherical convection with lab experiments that they actually built an experiment into the space shuttle because they couldn’t get a strong enough central force field on the ground,” said Seth Putterman, a UCLA physics professor and the lead author of the study. “What we showed is that our system of microwave-generated sound creates such strong gravity that Earth’s gravity no longer played a role. We no longer need to fly into space to do these experiments.”
UCLA researchers used microwaves to heat sulfuric gas in the glass sphere to 5,000 degrees Fahrenheit. The sound waves inside the sphere acted like gravity, forcing the movement of the hot, weakly ionized gas known as plasma in patterns similar to the plasma flows in stars.
“Sound fields act like gravity, at least when it comes to driving convection in gas,” said John Koulakis, a UCLA project scientist and first author of the study. “By using microwave-generated sound in a spherical flask of hot plasma, we have achieved a gravitational field 1,000 times stronger than Earth’s gravity.”
Hot gas rises on Earth’s surface because gravity pulls denser, cooler gas closer to the planet’s center.
In fact, the researchers found that hot, bright gas near the outer half of the sphere was also moving outward toward the sphere’s walls. The strong, sustained gravity produced turbulence similar to that seen near the Sun’s surface. In the inner half of the sphere, acoustic gravity reversed direction and pointed outward, causing hot gas to descend toward the center. In the experiment, acoustic gravity naturally kept the hottest plasma in the center of the sphere, where it also occurs in stars.
The ability to direct and manipulate plasma to reflect solar and planetary convection will help researchers understand and predict how solar weather affects spacecraft and satellite communication systems. For example, last year a solar storm destroyed 40 SpaceX satellites. The phenomenon is also problematic for military technology: the formation of turbulent plasma around hypersonic missiles, for example, can disrupt communication between weapon systems.
The study was funded in part by the Department of Defense’s Defense Advanced Research Projects Agency (DARPA) and the Air Force Office of Scientific Research.
Putterman and his colleagues are now expanding the experiment to better replicate the conditions they studied and to be able to observe the phenomenon in more detail and over longer periods of time.