The Cold War's end opened an opportunity for greater cooperation in planetary exploration for the United States and Russia. Two study groups were formed, Mars Together and FIRE and ICE. The Mars Together team developed a concept for a flight in 1998 that merged one U.S. Mars Surveyor 98 mission with the former Russian Mars 96 mission to further understanding of the Mars surface and atmosphere. The FIRE and ICE team developed concepts for a dual-spacecraft mission to the solar corona and for a mission to Pluto. The missions, scientific potential, and open issues are described. Jet Propulsion Laboratory INTERNATIONAL COOPERATION; MARS (PLANET); MARS EXPLORATION; MARS SURFACE; PLANETARY ATMOSPHERES; PLUTO (PLANET); RUSSIAN FEDERATION; SOLAR CORONA; SOLAR PROBES; SOLAR WIND; SPACE MISSIONS; UNITED STATES; IN SITU MEASUREMENT; PLASMA DIAGNOSTICS; SOLAR PLANETARY INTERACTIONS; SPACE PLASMAS; STELLAR STRUCTURE...