gravity assist

2021年02月25日 A Venus Flyby Image Credit: NASA, JHUAPL, Naval Research Lab, Guillermo Stenborg and Brendan Gallagher Explanation: On a mission to explore the inner heliosphere and solar corona, on July 11, 2020 the Wide-field Imager on board NASA’s Parker Solar Probe captured this stunning view of the nightside of Venus at distance of about 12,400 kilometers (7,693 miles). The spacecraft was making the third of seven gravity-assist flybys of the inner planet. The gravity-asssist flybys are designed to use the approach to Venus to help the probe alter its orbit to ultimately come within 6 million kilometers (4 million miles) of the solar surface in late 2025. A surprising image, the side-looking camera seems to peer through the clouds to show a dark feature near…