THE MAGNETIC FIELD IS A FUNDAMENTAL PHYSICAL QUANTITY AND ITS ACCURATE MEASUREMENT WITH ABSOLUTE STABILITY TO BETTER THAN 1 NT IS REQUIRED FOR MANY FUTURE SOLAR SYSTEM EXPLORATION MISSIONS. FUTURE MISSIONS REQUIRING THIS CAPABILITY INCLUDE THE EUROPA LANDER WHICH COULD RESOLVE INDUCTION SIGNALS TO CHARACTERIZE EUROPA'S SUB-SURFACE OCEAN; THE URANUS ORBITER AND PROBE WHICH SEEKS TO CHARACTERIZE URANUS' UNIQUE OFFSET MULTI-POLE MAGNETIC FIELD; AN ENCELADUS ORBITER; AND THE LUNAR GEOPHYSICAL NETWORK. ALL OF THESE MISSIONS REQUIRE MEASUREMENT OF SMALL-AMPLITUDE MAGNETIC SIGNALS WITH EXCELLENT LONG-TERM STABILITY. EUROPA INDUCED MAGNETIC FIELDS ARE A FEW NANO-TESLAS IN AMPLITUDE AND ARE GENERATED BY EXPOSURE TO PERIODIC MAGNETIC FIELD VARIATIONS RESULTING FROM THE ROTATION OF THE JOVIAN TILTED MAGNETIC FIELD ABOUT THE PLANETARY SPIN AXIS AT A PERIOD OF 11 H AND FROM THE MOON TRAVERSING THE MAGNETIC ENVIRONMENT OF ITS HOST PLANET IN AN ECCENTRIC ORBIT AT A PERIOD OF 85 H. MAGNETIC SOUNDING IS ALREADY AN INTEGRAL INVESTIGATION OF THE EUROPA MULTIPLE FLYBY MISSION AND IT IS IDEALLY COMPLEMENTED BY LANDER OBSERVATIONS BECAUSE THE INDUCTION RESPONSE IS SENSITIVE TO ALTITUDE SO THAT THE INDUCTION SCIENCE RETURN IS GREATLY ENHANCED BY COMBINING THE HIGH-ALTITUDE FLYBY OBSERVATIONS WITH THOSE FROM THE SURFACE. FLUXGATE MAGNETOMETERS ALONE CANNOT DELIVER THE REQUIRED PERFORMANCE BECAUSE THEIR CALIBRATION CAN DRIFT SO THAT LONG-TERM STABILITY IS NOT GUARANTEED. THE PROVEN SOLUTION IS TO PARTNER THE HIGH-HERITAGE FLUXGATE INSTRUMENTS WITH AN ABSOLUTE REFERENCE MAGNETOMETER WHICH SERVES AS A CALIBRATION SOURCE. THE FACT IS HOWEVER THAT THE MASS AND POWER OF SUCH INSTRUMENT COMBINATION AND OF MOST ATOMIC MAGNETOMETERS ALONE EXCEED THE CAPABILITIES OF MANY PLANETARY MISSIONS ESPECIALLY THOSE WITH A LANDER ELEMENT.