HORYU 4

HORYU 4 is an active satellite operated by Japan, launched on 2016-02-17 from TNSTA on the ASTRO-H launch. After 10 years in orbit, it continues to be tracked by global surveillance networks. It orbits in Low Earth Orbit (LEO) at altitudes between 257 km and 268 km with an inclination of 31.0°. It travels at approximately 27,906 km/h (7.75 km/s), completing one full orbit every 90 minutes — that’s roughly 16.06 orbits per day. Its near-circular orbit (eccentricity close to zero) means it maintains a very consistent altitude throughout each revolution. At its current altitude, the estimated orbital lifetime before atmospheric re-entry is weeks to months. Orbital Radar tracks HORYU 4 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

HORYU 4 orbits at an average altitude of 263 km in the lower reaches of Low Earth Orbit, where atmospheric drag is significant and orbital lifetimes are measured in months to a few years. This is the busiest corridor in space — home to crewed spacecraft, rapid-revisit imaging satellites and the densest part of the Starlink constellation. Within ±50 km of HORYU 4’s average altitude, there are currently 103 active payloads and 5 tracked debris or rocket body fragments — notable neighbours include STARLINK-1151, STARLINK-1143, STARLINK-1280. With an inclination of 31.0°, HORYU 4 passes over latitudes between 31.0°N and 31.0°S, covering the tropical and temperate zones where most of the world’s population resides. Low-to-mid inclination orbits are efficient to reach from equatorial and mid-latitude launch sites. Japan operates approximately 190 active satellites in total, of which 2 share a similar altitude band with HORYU 4.