While the Sun is the focus of Parker Solar Probe, Venus plays a critical role in the mission. The spacecraft will sweep past the planet a total of seven times over a seven-year mission, using the planet’s gravity to change its orbit. It is the gravity of Venus that allows Parker Solar Probe to fly closer and closer to the Sun on its mission to study the dynamics of the solar wind near its source.
But – along with orbital dynamics – these passages can also provide some unique and even unexpected views of the inner solar system. During the third mission, the onboard wide-angle thermal imager for the Parker Solar Probe, or WISPR, captured an unexpected image of the night side of the planet from a distance of 12,380 km.
WISPR is designed to capture visible light images of the solar corona and inner heliosphere, as well as the solar wind and its structures as they approach and fly past the spacecraft. On Venus, the camera detected a bright rim around the edge of the planet, which could be a night glow. This is the light emitted by oxygen atoms high in the atmosphere, which recombine into molecules on the planet’s night side. A noticeable dark feature in the center of the image is “Aphrodite Terra” (Aphrodite’s Land), the largest mountainous region on the surface of Venus. The element appears dark due to the lower temperature – the region is about 30 ° C lower than the environment.
This aspect of the imaging took the team by surprise, said Angelos Voorlidas, a WISPR scientist at the Johns Hopkins Applied Physics Laboratory (APL) in Lorel, Maryland, who coordinated the WISPR imaging campaign with Japan’s Akatsuki mission orbiting Venus. “WISPR has been adapted and tested for visible light observation. We expected to see clouds, but the camera was looking directly at the surface. “
“WISPR has effectively captured thermal radiation from the surface of Venus,” added Brian Wood, an astrophysicist and WISPR team member at the US Naval Research Laboratory in Washington DC. “This is very similar to the near infrared images taken by the Akatsuki spacecraft.”