Chinese experimental satellite Shijian-31 (SJ-31), neglected 16 June 2026 year, does use a unique highly elliptical orbit (HEO), which allows him to carry out a global survey of the geostationary belt (GEO) at an unusual angle. Although Beijing officially declared, that the device is intended for “research of the space environment”, space analysts classify it as a GEO situational awareness survey satellite.
Instead of the standard use of "Lightning" type orbits or the classic stay directly in the geostationary belt, SJ-31 operators used a non-standard combination of parameters:
Orbital motion: The satellite operates in an orbit with an inclination of about 63.4° and an eccentricity 0,69. Its orbital period is 12,5 hours (slightly less than two revolutions per day).
Changing the perigee argument: Classic "Molniya" satellites fix their apogee over high northern latitudes to ensure communication. However, the perigee argument of SJ-31 is 171°, which shifts its perigee to the equator, and the apogee is on the opposite side.
Top-down overview: The apogee of the satellite reaches a height of approx 39 900 km, which is about 4 100 km above the standard working geostationary orbit (~35 786 km). Майже третину кожного витка супутник проводить вище геостаціонарного поясу, двічі перетинаючи його під крутим кутом 63°.
Ефект сканування (дрейф): The period of rotation of the satellite is deliberately selected as follows, so that the trajectory of its projection on the Earth does not repeat itself exactly. As a result, the apogee slowly drifts around the planet, which allows the device to consistently inspect the entire geostationary belt every time 24 days.
Space Operations Safety Experts (including the Secure World Foundation and COMSPOC) point out, that such a trajectory gives China a significant advantage. Instead of focusing on a single object, SJ-31 works as a "patrol", which regularly collects optical or radio technical data on military and commercial satellites of other countries along the entire length of the equatorial belt.
Source: https://spacenews.com