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I found it very interesting (especially the sound recording) of the Venus Express detecting lightning on the planet Venus.

I found it strange watching the ' national geographic ' video about the discovery of lightning on Venus as the microwave dish of the spacecraft was pointed at Venus when it was ' detecting ' the lightning. This baffled me as I never knew that lightning would cause interferences at such a high frequency (I'm used to interferences being caused at VLFs - Very Low Frequencies). Did they use the spacecraft's transceiver to detect these interferences or was it a specialised piece of equipment which was intended for this job? - or was I mistaken for what was pointed at the planet?

(Below is a picture from the video - I'm unsure if this is the orientation it would have been in)

Here is the picture

I did try a few Google searches however I wasn't able to find much about the topic, only a few news stories about the discovery - I possibly had been searching the wrong thing...

I'm very interested if anyone knows anything more about this topic as I would love to possibly try the concept out myself one day.

Many thanks in advance.

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They used the magnetometer:

The confirming measurements of the electrical discharges were made with data obtained by the Venus Express magnetometer instrument provided by the Space Research Institute in Graz, Austria. The measurements were taken once a day for two minutes, during a period when the spacecraft was closest to Venus.

Paywalled article about the discovery should have more details.

On Venus Express, the magnetometer bandwidth is sufficient to record the lightning signals propagating in the whistler mode and will be used to map the occurrence of lightning across the nightside of the planet.

Whistler mode:

A whistler is a very low frequency or VLF electromagnetic (radio) wave generated by lightning.1 Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with a maximum amplitude usually at 3 kHz to 5 kHz. Although they are electromagnetic waves, they occur at audio frequencies, and can be converted to audio using a suitable receiver. They are produced by lightning strikes (mostly intracloud and return-path) where the impulse travels along the Earth's magnetic field lines from one hemisphere to the other.

They can be detected by a magnetometer because electromagnetic waves are, well, magnetic.

Presentation, 'The Strength of Venus Lightning':

  • When a lightning bolt discharges a cloud, the transient electrical current causes an electromagnetic wave. When this spherical wave reaches the ionosphere, it slows down and the wave front flattens. The wave then propagates vertically.
  • On Earth, this helps the waves to propagate into and through the ionosphere as at mid and high latitudes, the Earth’s high latitudes, the Earths magnetic field is vertical.
  • Terrestrial whistler mode signals reach satellites far above the atmosphere.

The electric signal strength seen in Venus’ atmosphere, when Pioneer Venus Orbiter dipped below the ionosphere, was used to predict that the electromagnetic signal could be seen by Venus Express' fluxgate magnetometer. So it was sampled rapidly enough to cover the frequency band of the PVO waves.

Venus Express was the first mission to record the waveform of the signals.

  • They are short duration bursts.
  • With high amplitudes up to 1 nT peak to peak.

Paper that describes the instrument

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  • $\begingroup$ Wow. Thank you @Hobbes for your response. I had no clue that the magnetometer had any significance in detecting the lightning. My mind was set that it was some radio interference which was detected by the spacecraft. No wonder why I wasn't able to find much on google. I'll be interested to see what you have yet to add. :) $\endgroup$ – Caspar P May 2 at 21:14
  • $\begingroup$ @CasparP: That's exactly what you detect in the magnetometer - radio waves, which are the aforementioned whistler modes. Those are electromagnetic wave modes that travel along the local magnetic field lines. The fascinating issue is now that this works near Venus at all just like near Earth. $\endgroup$ – AtmosphericPrisonEscape May 3 at 7:50
  • $\begingroup$ Thank you both for your responses - I found them really interesting. It makes complete sense now since I completely forgot about that magnetic waves are in radio waves. $\endgroup$ – Caspar P May 3 at 10:27

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