Campus, PAB 102/103
NASA's Neutron star Interior Composition Explorer (NICER) mission aims to answer longstanding questions about the physics and astrophysics of neutron stars, black holes, and other sources of cosmic X-ray emission, with a telescope on-board the International Space Station. Now in a Guest Observer phase, the mission has broadened its scientific horizons while continuing to pursue its "legacy science" objective to probe neutron stars -- through fast timing, sensitive spectroscopy, and long-term monitoring in the soft X-ray band, NICER is delivering sometimes-surprising insights into the structure, dynamics, and energetics of these extraordinary objects. The same capabilities, coupled with high throughput and flexibility in coordinating observations with other facilities, have also enabled revealing investigations of accreting black-hole systems. Following a brief overview of the mission, I present a sampling of recent results on pulsars and black-hole binaries, closing with plans for dramatically improving NICER's ability to respond to time-critical targets of opportunity.