The electromagnetic signature of lightning storms can be used to probe planetary atmospheres, providing information about the global density of constituents such as water, methane, and ammonia around the entire planet. Combining the technique with other instruments could provide a more accurate inventory of the planet’s atmosphere.

Schumann resonance lightning signature

The signature, known as Schumann Resonance, is created by lightning storms around the globe. On Earth, for example, there are an average of 50 lightning flashes every second. The discharges combine to create a beating pulse of electromagnetic waves that circles the Earth between the ground and the lower ionosphere.

Schumann Resonance, had only been detected from the Earth’s surface until 2011. Then, scientists detected it from space using NASA’s Vector Electric Field Instrument aboard the US Air Force Communications/Navigation Outage Forecast System satellite. That discovery opens up the possibility of using Schumann Resonance to study the atmospheres of other planets.

Fernando Simoes, a space scientist at NASA’s Goddard Space Flight Center in Greenbelt, MD and the first author on the paper explained. “The frequency of Schumann Resonance depends not only on the size of the planet but on what kinds of atoms and molecules exist in the atmosphere because they change the electrical conductivity. So we could use this technique remotely, say from about 600 miles above a planet’s surface, to look at how much water, methane, and ammonia is there. And if we can get a better sense of the abundance of these kinds of atoms in the outer planets, we would know more about the abundance in the original nebula from which the solar system evolved.” Accurate descriptions of planetary atmospheres might shed light on how the evolution of the solar system left the outer planets with a higher percentage of volatiles than the inner planets.

The detection of Schumann Resonance from orbit is just one the recent discoveries about the Earth’s atmosphere. In early 2011, researchers announced evidence from NASA’s Fermi Gamma-Ray Space Telescope showing that thunderstorms generated beams of antimatter (positrons) directed into space. The existence of upper-atmospheric lightning phenomenon such as sprites, elves, and blue jets was unknown to science until the 1990’s.

There’s still a lot we don’t know about the upper atmosphere, often called the “ignore-osphere” because it has been largely overlooked by science due to the difficulty of studying it with traditional tools. Reusable suborbital spacecraft will provide scientists with a valuable new research platform, help to reduce our ignorance. Citizen scientists may play a role in this research, too, by helping to analyze data collected by professional researchers or perhaps by developing new instruments and proving new techniques.

Perhaps we will soon see a prize for citizen-science research in atmospheric science.

Written by Astro1 on May 4th, 2012 , Atmospheric Science, Planetary science

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