A NASA probe heading for the Sun flew by Venus and picked up a natural radio signal, which happens to be the first measurement of the planet’s atmosphere in nearly 30 years.
The mission of NASA’s Parker Solar Probe is to dive close to the Sun, but in order to do that, it needed to slow down its speed before the approach, according to a NASA blog post. It did this by flying close enough to Venus that its gravity and atmosphere would lower its speed. NASA also saw this as an opportunity to measure the Venusian atmosphere for the first time in almost 30 years and so it did. The probe picked up a radio signal that has been translated into sound and you can listen to it below.
“The goal of flying by Venus is to slow down the spacecraft so that Parker Solar Probe can dive closer to the Sun,” Parker Solar Probe scientists, Nour E. Raouafi, of the Applied Physics Laboratory said in the blog post. “But we would not miss the opportunity to gather science data and provide unique insights into a mysterious planet such as Venus.”
This radio signal read came from a flyby the Parker Solar Probe made on July 11, 2020, and it was the closest flyby made to date – the probe was just 517 miles above the surface. It was the probe’s FIELDS instrument, which is named after the “electric and magnetic fields it measures in the Sun’s atmosphere,” according to NASA, that actually picked up the radio signal.
When the probe was close to Venus, the FIELDS instrument detected a natural, low-frequency radio signal for just seven minutes and this data caught the attention of Glyn Collison of NASA’s Goddard Space Flight Center, who is the lead scientist on this study. He recognized the shape and the strength of the signal, according to NASA, but he couldn’t quite place it.
Collison woke up the next day saying, “Oh my god, I know what this is,” NASA said, and that’s because it was a signal he recognized from some of his previous work: a similar signal appeared when NASA’s Galileo orbiter passed through the ionospheres of Jupiter’s moons in the early 2000s.
“Like Earth, Venus sports an electrically charged layer of gas at the upper edge of its atmosphere, called the ionosphere,” NASA’s blog post reads. “This sea of charged gases, or plasma, naturally emits radio waves that can be detected by instruments like FIELDS. When Collison and his team identified that signal, they realized Parker Solar Probe had skimmed Venus’ upper atmosphere.”
The team behind the study used the radio signals from Venus to calculate the density of the ionosphere that the probe passed through, something that hadn’t been done since the Pioneer Venus Orbiter’s 1992 passthrough. Data obtained from that probe and in the years that followed seemed to indicate the ionosphere was thinner during the Sun’s calm phase known as the solar minimum. That theory was impossible to confirm, but the Parker Solar Probe’s flyby might change that.
“When multiple missions are confirming the same result, one after the other, that gives you a lot of confidence that the thinning is real,” study co-author, Robin Ramstad, said in regards to the Parker Solar Probe also showing that Venus’ ionosphere was thinner during the time it passed by.
Venus and Earth have long been referred to as Twin planets – they were both born of a similar process, both are rocky, and their size and structural makeup is quite similar, but that doesn’t mean there aren’t differences. Venus doesn’t have a magnetic field like Earth, and if a human tried to walk on the surface of the planet as they do on Earth, they’d likely instantly die due to the surface boiling at temperatures hot enough to melt lead.
NASA says that at most, spacecrafts have lasted only a couple of hours on the planet. Despite how difficult it is to study Venus, its distance from Earth aside, it’s an important scientific mission to do so as it, “helps scientists understand how these twins have evolved, and what makes Earth-like planets habitable or not.”
“To see Venus now, it’s all about these little glimpses,” Collison said.
For more about Venus, read this story about how possible signs of life detected on the planet go back as far as 1978. Read this story about how the Moon is rusting and Earth might be the culprit after that and then check out this story about astronomers that have discovered 139 new “minor planets” at the edge of our solar system. Be sure to check out IGN’s list of the 25 best sci-fi movies, too.
Wesley LeBlanc is a freelance news writer and guide maker for IGN. You can follow him on Twitter @LeBlancWes.