While its main mission is to look at the Sun, NASA’s Parker solar probe will take every opportunity to send data back home to Earth.
The planet Venus represents precisely this opportunity, or rather, seven of them. Seven times during its mission, the probe will revolve around Venus to aid gravity, using the planet’s gravity as a slingshot to correct course and speed as it gets closer and closer to the Sun.
The solar probe performed the third of these maneuvers on July 11, 2020 and, as it approached, glamorized the night side of the planet using the Wide-Field Imager for Parker Solar Probe (WISPR) instrument. ).
Parker is not the only probe to take pictures of Venus as it travels through the inner solar system. BepiColombo, a European and Japanese space agency probing Mercury, made a video of Venus while doing a gravity assistance maneuver last year.
Venus steering wheel by BepiColombo. (ESA / BepiColombo / MTM)
These images show the planet as relatively smooth and without features. This is not at all surprising: Venus is surrounded by a toxic, thick atmosphere with clouds of sulfuric acid that reflect approximately 70% of the light hitting them. That is why Venus is one of the brightest objects in the night sky.
Parker’s team expected to see a featureless sphere, but that was not what they saw when they processed the WISPR data.
If you look at the image, you can see a bright glow around the edge of the planet. That, the team believes, is at night.
This is produced by atoms in the upper atmosphere. On the edge of the planet’s day, solar radiation divides carbon dioxide from the upper atmosphere into oxygen and carbon monoxide. When night falls, the atoms recombine into carbon dioxide, causing a glow.
This is something that also occurs on Earth and Mars, and has been seen before on Venus; his presence in the image of Parker is not surprising.
They’re not white stripes either, although the Parker team isn’t quite sure what they are, there are several candidates, including dust, cosmic rays, spacecraft ejected from the spacecraft after being hit by dust, or a combination of all of them.
(NASA / Johns Hopkins APL / Naval Research Laboratory / Guillermo Stenborg and Brendan Gallagher)
What is surprising is that dark face on the face of the planet. This is a region called Aphrodite Earth, the largest surface region on the planet.
The WISPR, designed to imagine the solar corona and coronal expulsions, is optimized for visible light observations, although it somehow looked through the clouds of Venus.
Scientists believe they know what happened, though. Venus currently has an active mission: the Akatsuki spacecraft of the Japanese Space Agency. It sends similar images, taken with its infrared camera, sensitive to temperature variations.
Aphrodite Earth, with its highest altitude, is much colder than the surrounding terrain, so it would be visible in infrared or near-infrared images of the planet.
“WISPR effectively captured the thermal emission from the Venusian surface,” said astrophysicist and WISPR team member Brian Wood of the U.S. Naval Research Laboratory. “It’s very similar to the images acquired by the Akatsuki spacecraft at near-infrared wavelengths.”
This means that WISPR could be more sensitive to infrared light than it was designed to be, which in turn opens up new possibilities for Parker’s main mission of studying the Sun. Currently, Parker’s team is closely analyzing the instrument’s specifications to find out what exactly it did.
“Either way,” said Angelos Vourlidas, a WISPR project scientist at the Johns Hopkins Laboratory of Applied Physics, “some exciting scientific opportunities await us.”