Celestial Navigation for Deep Space (and Timing) ... interesting data measurements, experimentation and demonstration. SpaceX has the NICER experiment in its "trunk" unpressurized cargo area. -- NICER : Neutron star Interior Composition ExploreR https://www.nasa.gov/mission_pages/station/research/experiments/1966.html Neutron stars, the glowing cinders left behind when massive stars explode as supernovas, are the densest objects in the universe and contain exotic states of matter that are impossible to replicate in any lab. They shine most brightly in narrow beams that sweep the sky as the stars spin; from a great distance, they appear to pulse like lighthouse beacons (hence the name “pulsars”). From its perch aboard the International Space Station (ISS), the Neutron star Interior Composition Explorer (NICER) payload studies the extraordinary physics of these stars, providing new insights into their nature and behavior. Through the embedded Station Explorer for X-ray Timing And Navigation Technology (SEXTANT) demonstration, it may pave the way for a future GPS-like system for spacecraft navigation anywhere in the Solar System using pulsars (known timing sequence) as natural beacons. Sent from iPad Air