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Space Station Info >> Recent Flybys
Recent Flybys
Some space probes
en route to other destinations have used
flybys of Venus to raise their speed by
means of the gravitational slingshot method.
These comprise the Galileo mission to Jupiter
and the Cassini-Huygens Mission to Saturn
(two flybys). Oddly, during Cassini's assessment
of the radiofrequency emissions of Venus
with its radio and plasma wave science instrument
during both the 1998 and 1999 flybys, it
saw absolutely no high-frequency radio waves
(0.125 to 16 MHz), which are commonly associated
with lightning. This is in direct opposition
to the findings of the Soviet Venera missions
20 years earlier. |
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It is postulated that perhaps
if Venus does have lightning; it might be some
type of low-frequency electrical activity, due
to the fact that radio signals cannot penetrate
the ionosphere at frequencies below about 1 megahertz.
An examination by physicist Donald Gurnett of
the University of Iowa of radio emissions of Venus
by the Galileo spacecraft during its gravity support
flyby in 1990 did expose what were interpreted
at the time to be indicative of lightning. But
the Galileo probe was over 60 times as distant
to Venus as was Cassini during its flyby, making
its observations considerably less important.
To this day it remains a obscurity as to whether
or not Venus does in fact have lightning in its
atmosphere.
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