Accidental discovery: Nasa’s Parker Solar Probe can see through the clouds around Venus

Venus‘ Aphrodite Terra highland region, captured by WISPR. Photo: NASA/Johns Hopkins APL/Naval Research Laboratory/Guillermo Stenborg and Brendan Gallagher

During the flyby, the special camera WISPR captured the thermal image of a dark area hiding the highland Aphrodite Terra

NASA’s Parker Solar Probe captured stunning views of Venus during its close flyby of the planet on July 11, 2020. During the mission’s third gravity assist, the onboard WISPR-camera (Wide-field Imager for Parker Solar Probe) captured a striking image of the planet’s nightside from only 7,693 miles away.

The picture has a prominent dark feature in the center which is Aphrodite Terra, the largest highland region on the Venusian surface known from earlier missions. The feature appears dark because of its lower temperature, about 30 degrees Celsius (85 degrees Fahrenheit) cooler than its surroundings.

That aspect of the image took the team by surprise, said Angelos Vourlidas, the WISPR project scientist from the Johns Hopkins Applied Physics Laboratory (APL) in Laurel, Maryland. “WISPR is tailored and tested for visible light observations of the Sun. Looking down on Venus, we expected to see clouds, but the camera peered right through to the surface.”

On Feb. 5, 1974, NASA's Mariner 10 mission took this first close-up photo of Venus. Photo: Nasa

“WISPR effectively captured the thermal emission of the Venusian surface,“ said Brian Wood, an astrophysicist and WISPR team member from the U.S. Naval Research Laboratory in Washington, D.C.

The scientist sent this surprising observation back to the lab to measure the instrument’s sensitivity to infrared light. If WISPR can indeed pick up near-infrared wavelengths of light, the unforeseen capability would provide new opportunities to study dust around the Sun and in the inner solar system. If it can’t pick up extra infrared wavelengths, then these images – showing signatures of features on Venus’ surface – may have revealed a previously unknown “window“ through the Venusian atmosphere.

“Either way,“ Vourlidas said, “some exciting science opportunities await us.“

For more insights, the WISPR team has planned a set of similar observations during the probe’s latest flyby on February 20, 2021. Mission team scientists expect to receive and process that data for analysis by the end of April.

Venus is Earth’s enigmatic sister planet with a similar size and mass. Much smaller Mercury and Mars are the other rocky planets in our solar system. Venus has a much denser atmosphere than Earth, made of more than 96% carbon dioxide. This gas composition gives its atmosphere a strong greenhouse effect and makes the planet hotter (464 °C; 867 °F) than Mercury, although it is more distant from the Sun.

Venus shining bright on a photo captured from the International Space Station on December 05, 2015. Photo: NASA/JAXA

Parker Solar Probe’s mission is to take images of the solar corona and inner heliosphere in visible light (using the WISPR camera), as well as images of the solar wind and its structures as it approaches and flies by our star. Venus plays a critical role in the mission: The spacecraft whips by it a total of seven times over the course of its seven-year mission, using the planet’s gravity to bend the spacecraft’s orbit. These Venus gravity assists allow Parker Solar Probe to fly closer and closer to the Sun.

Source: Nasa

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(02.03.2021)