Photo: ESA/DTU Space

ASIM observatory captures first giant lightning

Tuesday 29 May 18


Torsten Neubert
Chief Consultant
DTU Space
+45 45 25 97 31


Carol Anne Oxborrow
Special Consultant
DTU Space
+45 45 25 97 33

ASIM’s three instrument types

Broadly, ASIM has three types of instruments which capture visible images and detect invisible radiation:

  1. Photometers that count photons and can tell very precisely when something interesting is happening.

  2. Optical cameras that show where it is happening.

  3. X-ray detectors that capture more precisely what is happening by analysing incoming radiation.

In addition, ASIM’s measurements in space are supplemented by studies from Earth of the same phenomena.

DTU scientists have analysed the first amazing images of a violent thunderstorm over the Earth captured by the ASIM observatory at the International Space Station.

ASIM was launched and mounted on the outside of the International Space Station, ISS, last month, and the on-board detectors have now delivered the first pictures of thunder and lightning.
The thunderstorm was captured near the Sumatran coast in Indonesia. The lightning reached the upper layers of the atmosphere where ASIM captured them. What ASIM has captured seems to be a quite fascinating phenomenon that scientists are keen to investigate.

“Although the clouds partially blocked the lightning, our instruments captured very powerful electrical discharges high up in the atmosphere. We believe it could be one of the phenomena known as ‘elves’,” says Torsten Neubert, Senior Executive Officer at DTU Space, who is scientifically responsible for ASIM.

“We have collected 100,000 measurements per second of this amazing force of nature. We did that using ASIM’s powerful photometers that count photons, or light particles, detecting that something interesting is happening.”

Lightning phenomena 80-100 km above Earth
Elves are rapidly expanding rings in the upper atmosphere, occurring 80-100 km above Earth when electrons collide with nitrogen molecules during thunderstorms. These rings can spread over hundreds of kilometres.

They are some of the strongest visible phenomena above thunderclouds and are collectively called Transient Luminous Emissions (TLEs). (see footage here )

“So far, only the optical instruments capturing visible light are used. We have even more exciting research to look forward to when the other instruments are ready,” says Torsten Neubert.

ASIM has multiple types of instruments Photometers that count photons, optical cameras and X-ray detectors that capture and measure incoming radiation from lightning and related phenomena such as elves. The lightning strikes being analysed go outwards into space—not downwards as the lightning strikes typically visible from Earth. This happens around 20-100 km above Earth.

New data centre at DTU
ASIM data is analysed at a purpose-built DTU Space data centre. ISS sends data down to Earth to be forwarded to DTU Space via the ESA Space Operations Centre in Belgium. At DTU, the data is cleaned and sorted to remove ‘noise’, among other things, to prep it for the researchers.

ASIM points down towards Earth from its position on the Columbus module on the outside of the ISS 400 km out in space. From this position, the instruments can observe energy discharges from lightning and related processes in connection with thunderstorms.

ASIM is anchored in the European Space Agency ESA, but is under Danish leadership. DTU Space undertakes the scientific leadership, while the Danish company Terma undertakes the technical leadership of the project.

See ESA news in English about the new images.

Watch a short ESA video about ASIM’s journey from its launch in Florida to being mounted on the space station ISS. 

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