Do giant flashes of lightning striking upwards from thunderclouds merely pose an extraordinarily spectacular view? Or do theyactually alter the chemical composition of the atmosphere, playing arole in ozone depletion and the climate on Earth? This is the keyquestion that may be answered by specially designed cameras, which ESAproposes to place on board the International Space Station.
TheInternational Space Station (ISS) is the ideal setting for studies ofspectacular natural phenomena well hidden from us on Earth - so-calledred sprites, blue jets and elves: vast flashes of lightning strikingnot from clouds to the ground, but from clouds towards space.
Normallythe word lightning makes us think of sharp zigzag lines striking fromthe clouds to the ground. Above the clouds however a quite differenttype of lightning can be seen. There lightning is colourful - mainlyred and blue - and covers large areas of the upper atmosphere.Sometimes it can even reach the border between the atmosphere and space.
Overthe last few years scientists from the Danish National Space Centrehave studied these flashes with cameras placed on mountain tops. Everyso often the cameras would catch a flash of lightning striking up froma thunder cloud at a lower altitude.
Placing cameras and otherinstruments on the Space Station would, however, dramatically improvethe chances of seeing the giant flashes and study their effect on theatmosphere. The Danish National Space Centre is currently studying apackage of instruments for just that purpose, known as theAtmosphere-Space Interactions Monitor (ASIM). ESA has now selected ASIMfor a feasibility study (known as Phase A).
"The question is howare these giant flashes of lightning created and how often do they takeplace", says senior scientist Torben Neubert, head of the project atDanish National Space Centre.
It may well be that the largeelectrical bursts remove ozone from the atmosphere, and in so doinginfluence the climate. "We need to understand the natural processeswhich influence the atmosphere and this can help us decide whichchanges in the climate are man-made", Torben Neubert states.
It is still too early to say when the cameras will actually enter into service in space.
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