- China's Shijian-31 satellite, launched in June 2024, operates in a unique Molniya-type orbit to monitor the geostationary belt.
- The satellite uses a highly elliptical orbit with an inclination of 63.4 degrees, but its apogee is over the equator instead of the northern hemisphere, allowing it to sweep the GEO belt.
- Shijian-31 orbits every 12.5 hours, shifting approximately 15.7 degrees in longitude per orbit, enabling it to sweep the entire GEO belt every 23 days.
- Its perigee is just under 2,000 km and apogee about 39,900 km, a few thousand kilometers beyond the GEO belt, providing a unique vantage point.
- The satellite is part of China's Shijian experimental series, often used for space environment exploration and space situational awareness (SSA).
- Analysts note that Shijian-31 could potentially perform inspections of GEO satellites with a small fuel burn to lower its apogee into the GEO neighborhood.
- The mission is described as a demonstration of orbital mechanics mastery and creativity, and may reflect a larger trend toward inspector satellites and enhanced GEO awareness.