On October 29, 1991, Galileo became the first spacecraft to encounter an asteroid when it flew within 1,600 kilometers of Gaspra, capturing detailed images of its irregular, cratered surface.

During its flyby on August 28, 1993, Galileo captured detailed images of the asteroid Ida from a distance of 2,400 kilometers, revealing it to be an S-type asteroid with an unexpected companion moon later named Dactyl.

Galileo orbited Jupiter for nearly eight years, conducting 35 flybys of the Jovian moons, discovering evidence of subsurface oceans on Europa, and studying the planet's atmosphere until its deliberate destruction in Jupiter's atmosphere in 2003.

During its flyby of Io in 1995, Galileo discovered that the moon has a magnetic field and an iron-rich core, while also capturing unprecedented images of active volcanic plumes erupting from its surface.

During its second Ganymede flyby on September 6, 1996, Galileo passed within 261 kilometers of the Jovian moon's surface, capturing high-resolution images and gathering data that revealed the presence of a magnetic field and possible subsurface ocean.

Galileo made its closest approach to Callisto on November 4, 1996, coming within 1,136 kilometers of the moon's surface and capturing detailed images of its heavily cratered terrain.

Galileo performed detailed observations of Europa during multiple flybys in 1997, revealing strong evidence of a liquid water ocean beneath the moon's icy surface.