NASA’s Parker Solar Probe Discovers Radio Signal in Venus’ Atmosphere
martyb writes:
NASA's Parker Solar Probe Discovers Radio Signal in Venus' Atmosphere:
During a brief swing by Venus, NASA's Parker Solar Probe detected a natural radio signal that revealed the spacecraft had flown through the planet's upper atmosphere. This was the first direct measurement of the Venusian atmosphere in nearly 30 years - and it looks quite different from Venus past. A study published today confirms that Venus' upper atmosphere undergoes puzzling changes over a solar cycle, the Sun's 11-year activity cycle. This marks the latest clue to untangling how and why Venus and Earth are so different.
[...] On July 11, 2020, Parker Solar Probe swung by Venus in its third flyby. Each flyby is designed to leverage the planet's gravity to fly the spacecraft closer and closer to the Sun. The mission - managed by Johns Hopkins Applied Physics Laboratory in Laurel, Maryland - made its closest flyby of Venus yet, passing just 517 miles (833 km) above the surface.
[...] "I was just so excited to have new data from Venus," said Glyn Collison of NASA's Goddard Space Flight Center in Greenbelt, Maryland, the lead scientist on the study, published today (May 3, 2021) in Geophysical Research Letters. A Venus expert, Collinson has pored over all the Venus data available - from past missions like NASA's Pioneer Venus Orbiter and ESA's (the European Space Agency) Venus Express - several times.
One of Parker Solar Probe's instruments is FIELDS, named for the electric and magnetic fields it measures in the Sun's atmosphere. For just seven minutes - when Parker Solar Probe was closest to Venus - FIELDS detected a natural, low-frequency radio signal. The thin frown in the data caught Collinson's attention.
[...] Collinson recognized the signal from his previous work with NASA's Galileo orbiter, which explored Jupiter and its moons before the mission ended in 2003. A similar frown appeared whenever the spacecraft passed through the ionospheres of Jupiter's moons.
[...] The observations from Parker Solar Probe's recent flyby, which occurred six months after the latest solar minimum, verify the puzzle in Venus' ionosphere. Indeed, Venus' ionosphere is much thinner compared to previous measurements taken during solar maximum.
Journal Reference:
Glyn A. Collinson, Robin Ramstad, Alex Glocer, et al. Depleted Plasma Densities in the Ionosphere of Venus Near Solar Minimum From Parker Solar Probe Observations of Upper Hybrid Resonance Emission, Geophysical Research Letters (DOI: 10.1029/2020GL092243)
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