Complex sentence: During this time he also became a co-investigator on the magnetometer team for the Galileo mission to Jupiter, which led to several discoveries in conjunction with Margaret Kivelson concerning the magnetism of the Galilean moons and the asteroid Gaspra.
Split into simpler sentences: During this time he also was a co-investigator on the magnetometer team for the Galileo mission to Jupiter. The magnetic field measurements made by this magnetometer led to several discoveries in conjunction with Margaret Kivelson concerning the magnetism of the Galilean moons and asteroid Gaspra.