For years, scientists have been piecing together evidence of peculiar phenomena known as red sprites, blue jets, pixies and elves – exotic types of electrical discharges that emanate from thunderstorms.
ESA astronaut Andreas Mogensen during his 10-day mission on the International Space Station in 2015 performed an experiment called Thor, after the god of thunder, lightning and storms in Nordic mythology. Thor had Andreas test a new thundercloud imaging system that looks at the electrification of lighting with the most sensitive camera on the orbiting outpost. Denmark’s National Space Institute has now published the results.
Researchers are particularly interested in newly-discovered lights that occur in the upper atmosphere during thunderstorms called red sprites, blue jets and elves. Sprites last 20 milliseconds at most, and to capture them on camera is a real challenge. Blue jets are found up to 50 km altitude with red sprites occurring between 60-80 km altitude. The violent electric discharges are very difficult to capture from the ground because the atmosphere blocks radiation.
Apart from covering all the main thunderstorm regions, the International Space Station has the lowest orbit available for observation at around 400 km altitude – imaging satellites mostly operate at 800 km. Andreas received the coordinates of a few possible thunderstorms together with the times and instructions on which lens, filter and camera settings to use. He aimed for cloud turrets – cloud pillars extending into the upper atmosphere – and shot a 160 second video as he flew 250 miles above the Bay of Bengal at a speed of 30,000 km/h.
The video – a first of its kind – shows many kilometre-wide blue flashes around 18 km altitude, including a pulsating blue jet reaching 40 km. The video also shows a spidery tangle of red sprites flashing upward from the clouds.
Satellites have documented such phenomena before, but Mogensen had much better view of the discharges. Close study of the discharges, known as transient luminous events, could help scientists understand more fully how the atmosphere serves as a shield against space radiation.
“It is not every day that you get to capture a new weather phenomenon on film, so I am very pleased with the result – but even more so that researchers will be able to investigate these intriguing thunderstorms in more detail soon,” Mogensen said in a report from the European Space Agency.
Mogensen is referring to the Atmosphere-Space Interactions Monitor, or ASIM, an ESA experiment that’s slated for installation on the exterior of the space station’s Columbus module later this year. ASIM’s primary mission is to monitor thunderstorms continuously for transient luminous events – and watch for even more mysterious gamma ray flashes that have been detected in the upper atmosphere.