Overview of the 1989 mission selections: A quality thrust in particle astrophysics

The space missions selected over the past year in response to NASA Announcements of Opportunity include an ensemble of unprecedented particle astrophysics investigations: (1) a polar‐orbiting, Scout‐class Small Explorer mission; (2) a Delta‐class Explorer mission in a halo orbit at the L1 Lagrangian point; (3) a secondary payload on the Earth Observing System polar platform; (4) the Astromag facility on the early Space Station Freedom with three complementary first‐generation investigations; and (5) a fourth Space Station Freedom payload to investigate actinide nuclei. There is a one‐to‐one mapping of these missions with the top priorities of the Cosmic Ray Program Working Group. Carrying them to completion will ensure U.S. preeminence in particle astrophysics well into the first decade of the next century. Investigations made in conjunction with a potential lunar base might provide the next quantum step in the 21st century.