The Outer Solar System: Chemical Constraints at Low Temperatures on Planet Formation

o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o oo o o o o o o o o o o o o o o o o o o o o o o o o o oo o The past decade has seen p werful gr undand space-based techniques applied t the investigati n f the c mp siti n f uter s lar system b dies, including the spectacular measurements f He/H, is t pe rati s, and n ble gas abundances in the j vian atm sphere by the pr be; impr ved deuterium and trace species measurements in the atm spheres f the giant planets and Titan; and first detecti n f abs rpti n features n the surface f a Kuiper Belt bject. In this chapter we review the new bservati ns and discuss h w they c nstrain the c mp siti n f prim rdial reserv irs supplying material t the giant planets, their m ns, and ther uter s lar system b dies. Planned r anticipated planetary missi ns in the next decade, al ng with impr ved gr und-based capability n giant telesc pes, will enable m dels f the early ev luti n f the uter s lar system t be tested and impr ved, ultimately t pr vide a picture f h w the f ur giant planets and their m ns came t be.