HERMES-3

HERMES-3 is an active satellite operated by Italy, launched on 2025-03-15 from Vandenberg SFB, California. As a relatively recent addition to the catalogue, its orbital elements are well-characterised. It orbits in Low Earth Orbit (LEO) at altitudes between 458 km and 469 km with an inclination of 97.4°. It travels at approximately 27,493 km/h (7.64 km/s), completing one full orbit every 94 minutes — that’s roughly 15.34 orbits per day. Its near-polar, sun-synchronous orbit means it passes over any given point on Earth at approximately the same local solar time, ideal for consistent Earth observation lighting conditions. 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 ~1–3 years. Orbital Radar tracks HERMES-3 in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

HERMES-3 orbits at an average altitude of 464 km in a sun-synchronous orbit (SSO), a specialised subset of LEO where the orbital plane precesses to maintain a constant angle relative to the Sun. This provides consistent lighting conditions on every pass — essential for Earth observation, weather monitoring and environmental science. Within ±50 km of HERMES-3’s average altitude, there are currently 7,991 active payloads and 178 tracked debris or rocket body fragments — notable neighbours include STARLINK-1008, STARLINK-1012, STARLINK-1017. This makes it one of the more crowded altitude bands, containing roughly 45.9% of all active satellites. With an inclination of 97.4°, HERMES-3 passes over latitudes between 97.4°N and 97.4°S, providing near-global coverage including the polar regions. Polar and near-polar orbits are used for reconnaissance, weather monitoring and Earth-observation missions that need to image every part of the planet. Italy operates approximately 88 active satellites in total, of which 35 share a similar altitude band with HERMES-3.