It’s not often that I photograph someone who can accurately guess the shutter speed of my camera by simply hearing the click. But such is the attention to technical detail of NASA’s chief scientist John Grunsfeld, a Chicago-born astronaut who repaired the Hubble Space Telescope and who the Tribune profiled this past Sunday. Immediately after his slide presentation at the Adler Planetarium, I was to shoot a cover photo that was more interesting than a guy standing next to a museum exhibit. Pressed for time, we quickly entered the Atwood Sphere, an interactive exhibit, and while a docent held an off-camera flash, I used a tripod and a long exposure to capture the spinning sphere that shows the night sky. It was a bit of a calculated gamble, since we only had time for about 10 frames, and there wasn’t a lot of time for testing. At first I tried light-painting, but there was too much movement on our mechanical platform. Given that his grandfather helped design the dome of the Planetarium building, there was a palpable sense that history and astronomy had come full circle for the Grunsfeld clan.