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This year, images captured by cameras on the International Space Station have revealed answers to the question that has been puzzling scientists since the early 90s. What causes the phenomena of gamma-ray bursts? Every day, thunderstorms happen all over the globe, and these are accompanied by bursts of one of the highest-energy light forms found on earth - gamma rays.
Even small storms can produce them, not just those generating large amounts of energy. But how these bursts of gamma rays are produced has alluded scientists for over two decades.
Space Station’s Cameras
In 2019, the space station’s cameras were able to record the moment when hundreds of gamma-ray flashes occurred in the middle of a thunderstorm, and by comparing them to the lightening energy that was happening at the same time, a mystery is being unveiled. Physicists are now looking at these findings as revolutionary in the field.
Before the flash of a lightning bolt, the atmosphere becomes home to intense flowing electric fields, and the charged particles generate terrestrial gamma-ray flashes (TGFs), which occur moments before we see a flash of lightning. Down on the ground, we cannot witness these gamma-ray bursts, but above the earth, the space station’s Atmosphere–Space Interactions Monitor (ASIM) captured the entire event.
Built by a world-leading team of numerous European companies and universities, the ASIM incorporates box-shaped cameras and sensors designed with the capabilities to study both lightning and TGFs.
The Story Behind Gamma-Ray Bursts
Images from the cameras have illustrated the findings in detail. Over a ten-month course of data collection, the ASIM was able to determine the sequence that causes gamma-ray bursts. It begins with electrically charged particles moving down a conductive channel, causing a low energy flash of light, which then leads to a huge burst of gamma rays (TGF bursts), followed by a strong electric current along the same path, creating a flash of lightning.
The data supports one theory of TGF that a gamma ray's bursts are facilitated by a small and strong electric field at the beginning of a conductive channel, and it discounts other theories, such as a strong electric field building in the clouds.
At this point, the research is encouraging and provides a huge leap forward in the understanding of TGF formation. However, more data will need to be collected and analyzed to confirm the full series of events related to the existence of TGFs.
The project will continue to collect data over the next two years. With thunderstorms happening daily, all around the world, the project is predicted to gather a wealth of data that should help provide further insights into the nature of TGFs.
The Future of Space Research
Norwegian space physicist, Nikolai Østgaard, has said that the future of the research will involve attempts to get closer to the thunderstorms in order to gain clearer images and further insight. At the moment, the images are taken by the ASIM about 400 kilometers from above the Earth’s surface.
Given that TGFs have been found to occur only 11-13 kilometers above the surface, Østgaard and the team plan to get as close as they can to them. This will likely involve flying airplanes equipped with gamma-ray detectors in close range to thunderstorms. We can expect this research to commence in 2021 at the earliest.
This data will be looked at alongside that which will be collected from the ASIM, and experts are optimistic that the mystery of TGFs will be completely unraveled in the next few years.