Roger Bruce Chaffee was born on February 15, 1935, in Grand Rapids, Michigan, the second child of Donald Lynn Chaffee and Blanche May (Mike) Chaffee (née Mosher). He had an older sister, Donna, born two years earlier. In January 1935, in their hometown of Greenville, Michigan, his father was diagnosed with scarlet fever, and Mike moved in with her parents in Grand Rapids, where Roger was born. The family spent the next seven years in Greenville before moving to Grand Rapids, where his father took a job as the chief Army Ordnance inspector at the Doehler-Jarvis plant. Chaffee’s interest in aerospace was sparked at a young age when his father, a former barnstorming pilot, took him on his first flight at the age of seven. Chaffee was thrilled by the flight and soon after started building model airplanes with his father.
Ganymede: Ganymede is both the largest moon of Jupiter, our Solar System's planetary behemoth, as well as the largest moon in our entire Solar system. Observations of Ganymede by the HST in 2015 suggested the existence of a subsurface saline ocean. This is because patterns in auroral belts and rocking of the magnetic field hinted at the presence of an ocean. It is estimated to be approximately 100 kilometers deep with a surface situated below a crust of 150 kilometers. At last, on July 1, 2004, the Cassini spacecraft fired off its breaking rocket, glided into orbit around Saturn, and started taking pictures that left scientists in awe. It wasn't as if they hadn't been prepared for such wonders. The weeks leading up to Cassini's arrival at Saturn had served to intensify their already heated anticipation. It seemed as if each approach-picture taken was more enticing than the one preceding it. We live in a Cosmic "shooting gallery". Objects inhabiting our Solar System have been profusely and mercilessly blasted by showering asteroids and comets for billions and billions of years. However, planets and large moons have their way of smoothing away the scars--their strong gravity pulls them into a nice ball-like spherical shape. Furthermore, some of these larger spheres possess sufficient internal heat to cause flows of fiery lava and other volcanic features that can fill in the scars of impact craters. A few such large bodies are blasted by strong winds and pouring rains, which also erode away the pockmarks left on their surfaces by showering impactors.