NAVSTAR 51 (USA 166) is a payload in MEO orbit, operated by US Air Force Space and Missile Center, launched 2003.
Orbital data last updated 3 days ago. This may not reflect the current orbital state, not for operational use or collision avoidance. That number is the age of the measurement itself, not of our last check. We look for newer orbital data every six hours and publish whatever the tracking catalogue has released; when nothing newer has been released, the measurement below stays where it is. This is normal for this orbit. 63 of the 187 tracked objects in MEO were also last measured at least this long ago. Objects on this kind of path spend much of their time far from the ground sensors that track them, so they are re-measured far less often than something in a low orbit passing overhead several times a day. This record was last refreshed on 2026-10-22.Why?
See it moving on the 3D globe alongside every other active object, propagated in your browser.
//Orbital data is approximate and not for operational use. Last ingested from CelesTrak on Oct 22, 2026.