Page 21 - EngineerIT November 2022

SPACE SCIENCES

Powerful gamma-ray burst made

currents flow in the Earth

stronomers have never seen anything quite like it. Dr Tony Phillips of Space my hobby. I started doing VLF radio
Weather.com wrote that on 9 October 2022, Earth-orbiting satellites detected measurements in the 1970s when I was
Athe strongest gamma-ray burst (GRB) in modern history: GRB221009A. It caused in high school. This is the first time I have
electrical currents to flow through the surface of our planet. detected a gamma-ray burst.”
Klekociuk’s unusual “ham rig”
Dr Andrew Klekociuk in Tasmania recorded the effect using an earth probe antenna: uses Earth itself as a giant antenna.
In his back garden there are two
metal spikes stuck into the ground, 75
metres apart. They are connected to
a radio receiver via insulated buried
wires. In recent years radio amateurs
have been experimenting with this
weird kind of antenna to detect VLF
radio signals circling our planet in the
Earth-ionosphere wave guide. Earth’s
crust forms one of the wave guide’s
walls, allowing Earth probe antennas to
detect distant transmitters.
“During the gamma-ray burst
I detected flickering from multiple
stations,” says Klekociuk, who
constructed this map showing
transmission paths illuminated by the
GRB:
Note: Data from STIX has been flipped
(increasing counts go down) to ease
comparison of the two wave forms. NWC
is a VLF transmitter in Australia.

The blue curve is a signal from
Klekociuk’s antenna, which was sensing
VLF (very low frequency) currents in
the soil at the time of the blast. The
orange curve shows the gamma-ray
burst recorded by the high-energy STIX
telescope on Europe’s solar orbiter
space craft, one of many space crafts
that detected the event. The wave
forms are a nearly perfect match. The
X-ray spectrometer/telescope (STIX)
studies solar X-ray emissions, which
are exclusively emitted during solar
flares.
“I am a climate scientist at the NWC, VTX3, Mokpo and NML are VLF transmitters that Klekociuk monitors using his earth
Australian Antarctic Division - that’s probe antenna. GRB effects were observed for all except NML, which was outside the
my day job,” says Klekociuk. “VLF is radiation footprint.

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