There are six instruments on the probe Galileo. They are the atmosphere structure instrument which provides climate, density, pressure and molecular weight.  The nephelometer which locates and measures cloud particles and uses lasers that measure the light in order to figure that out, the lightning/ Radio Emissions detector that searches and records radio bursts and flashes made by lightning from Jupiter's many storms, the Helium Abundance Detector that detects the ratio of helium in Jupiter's atmosphere  It also determines the abundance of helium.  The next is the Net Flux Radiometer which senses the difference between the flux of light and heat that is being radiated upward and downward.  This information tells about the location of cloud layers and atmospheric wind power source.  The last of Galileo's instruments is the Energetic Particles Instrument that is used to measure the flux of electrons, protons, alpha particles and heavy ions as Galileo passes through the innermost part of Jupiter's atmosphere.  The orbiter has made many passes by the four large moons of Jupiter (Io, Europa, Ganymede and Callisto) and is still functioning in it's sixth year in orbit, returning remarkable scientific data .  It will end it's tour in 2003, probably by falling into the cloud tops of Jupiter to join the probe in a dramatic finale to a remarkable mission.