A solar probe measuring natural radio emissions into Venus’ atmosphere

This dramatic image of Venus was taken in July 2020 by the Parker Solar Probe, a NASA space probe that will investigate the sun closely. (NASA / Johns Hopkins APL / Naval Research Laboratory / Guillermo Stenborg and Brendan Gallagher)

This indicates that the space probe has flown through the planet’s ionosphere. It was the first time in nearly three decades that Venus’ atmosphere was measured directly. Analysis of the data collected in flight confirms that the ionosphere of Venus shows significant differences.

The measurements were taken on July 11, 2020, when the Parker probe passed Venus for the third time, this time at a distance of just 833 kilometers. These flights are designed to maneuver the spacecraft close to the sun.

One of the Parker Solar Probe instruments will soon measure the electric and magnetic fields in the sun’s atmosphere. But on this occasion he did so with Venus. Like Earth, this planet contains a layer of charged gas particles high in its atmosphere. This so-called ionosphere is a source of low-frequency radio radiation.

Not hot enough to live in it

A team of scientists used this radio emission to measure the density of the ionosphere – something that was actually done by the Pioneer Venus Orbiter in 1992. At that time, the sun was at its zenith, while it is now at its coolest.

Parker’s measurements show that the ionosphere of Venus was much thinner last year than it was in 1992. This confirms the impression, based on telescope observations from Earth, that the planet’s ionosphere is much thinner during the minimum solar than it is during the maximum sun.

A study of the ionosphere of Venus should provide further insight into the evolution of the planet’s atmosphere, which used to be very similar to Earth but is now uninhabitable hot.