OPS 3674 (VELA 4)

OPS 3674 (VELA 4) is an active satellite operated by USAF SSD (United States), launched on 1964-07-17 from Cape Canaveral Space Force Station, United States on the Vela 2A launch. After more than 62 years in orbit, it is one of the longest-surviving objects in the space catalogue. It orbits in Medium Earth Orbit (MEO) at altitudes between 29,937 km and 176,155 km with an inclination of 48.4°. It travels at approximately 6,871 km/h (1.91 km/s), completing one full orbit every 100.1 hours — that’s roughly 0.24 orbits per day. Its orbital eccentricity of 0.6682 gives it a noticeably elliptical path, with significant altitude variation between perigee and apogee. At geostationary altitude, there is no meaningful atmospheric drag — this object will remain in orbit indefinitely unless actively deorbited. Orbital Radar tracks OPS 3674 (VELA 4) in real time using the latest two-line element set (TLE) data, providing live position, altitude, speed and orbital path updated continuously.

OPS 3674 (VELA 4) orbits at an average altitude of 103,046 km in Medium Earth Orbit, the region between LEO and GEO (2,000–35,786 km). MEO’s higher altitude gives each satellite a much larger ground footprint than LEO, meaning fewer spacecraft are needed for global coverage — but signal latency is higher and radiation from the Van Allen belts is a significant design constraint. With an inclination of 48.4°, OPS 3674 (VELA 4) passes over latitudes between 48.4°N and 48.4°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. United States operates approximately 13,279 active satellites in total.