|A taste of Mercury geology – annotated|
Last night, the ESA's BepiColombo probe made a very close pass by Mercury coming within 200km of the surface. That's like the ISS over the Earth. It wasn't going into orbit around Mercury though, it is just flying by on it's way, presumably, around the sun. So, if you are like me, you think this picture was taken at the closest approach, but if that's the case, why can we see the whole planet? Why are we not just looking at the state of Nuevo Arkansas? Silly goose, the BepiColombo snuck up from the night side:
Images were acquired from about five minutes after the time of close approach and up to four hours later. Because BepiColombo arrived on the planet’s nightside, conditions were not ideal to take images directly at the closest approach, thus the closest image was captured from a distance of about 1000 km.
Now I'm looking for a trajectory plot and a velocity chart, well, I should be, but I ain't. I will hazard a guess that it was traveling upwards of ten miles per second at closest approach.