High above the Earth, luminous plasmas that occasionally light up the night sky at high altitudes have become the focus of NASA and ESA scientists, who are using instruments aboard the International Space Station (ISS) to help shed light on their mysterious appearances.
Known as transient luminous events (TLEs), a range of different kinds of these manifestations are known to exist. These include ‘blue jets,’ which are often observed stretching from the tops of clouds into the upper stratosphere, as well as light phenomena that appear in even higher regions formally known as Stratospheric/Mesospheric Perturbations Resulting from Intense Thunderstorm Electrification, or SPRITES.
Ascending above these, faint, greenish areas sometimes resembling globes of light can appear, which are known as ‘ghosts,’ and at even greater altitudes near the boundary between the mesosphere and the troposphere, large, expanding halos or rings of light produced from electromagnetic pulses from lightning known as ELVES (Emission of Light and Very low frequency perturbations due to Electromagnetic pulse Sources) can also occur.
Closing in on Transient Luminous Events
Although recognition of the various types of TLEs occurred relatively recently, observations of mysterious, often colorful light displays have been reported for much longer. Because of their often fleeting appearances, the existence of these phenomena had been a subject of debate prior to the collection of space-based imagery that has left little doubt about the diversity of electrical phenomena that populates the region between the Earth’s surface and outer space.
However, studying these phenomena from the ground is problematic, since these luminous events occur at such high altitudes that they can seldom be observed using Earth-based instruments.
To overcome this, the European Space Agency uses data collected from its innovative Atmosphere–Space Interactions Monitor, or ASIM. From its position outside the European space laboratory Columbus on board the ISS, ASIM is helping scientists unravel important new clues about how TLEs and other atmospheric phenomena can be studied to improve our weather modeling capabilities.
Unveiling ‘ELVES’ and ‘Coronas’
One study produced with ASIM data has already helped scientists determine how the massive ringlike ELVES that occur near the boundary between the mesosphere and the troposphere can influence ionospheric activity.
In separate studies that rely on ASIM data, the properties of corona discharges which past research has associated with highly energetic but fleeting electrical bursts in the upper portions of clouds, have been accurately modeled.
Separate investigations have successfully captured imagery of high-altitude thunderstorms from aboard the ISS during the ESA’s Thor-Davis experiment, which focused on rare lightning and thunder manifestations. By logging imagery at close to 100,000 frames per second, such capabilities offer a useful ability to detect and monitor potentially dangerous storm activity from space.
Mitigating Communication and Aircraft Issues
One reason the ESA and NASA are studying these phenomena is because on occasion, various TLEs can impact communications on the ground, and may even present potential dangers for aircraft, and even spacecraft.
Luminous manifestations also aren’t the only phenomena NASA scientists are studying that appear in Earth’s upper atmosphere. Instruments aboard the ISS are also currently collecting data on thunderstorm activity, conventional forms of lightning, and other atmospheric phenomena.
In addition to mitigating potential hazards associated with TLEs and other atmospheric events, having a better understanding of what causes them may also help scientists improve our ability to forecast weather by generating more accurate atmospheric models, thereby expanding our overall understanding of the events occurring in Earth’s skies.
Micah Hanks is the Editor-in-Chief and Co-Founder of The Debrief. He can be reached by email at micah@thedebrief.org. Follow his work at micahhanks.com and on X: @MicahHanks.