The Soviet spacecraft Kosmos-1707 deorbited on September 17, 2026, 40 years and 9 months after launch. According to tracking catalogs, the spacecraft had the international designation 1985-113A and NORAD number 16326.
Kosmos-1707 was launched into orbit on December 12, 1985, from the Plesetsk Cosmodrome by a Tsiklon-3 rocket. Catalogs classify the spacecraft as part of the Tselina-D system, designed for space electronic intelligence. Its working orbit was approximately 600 km high, so after the completion of active operations, the spacecraft remained in near-Earth space for decades.
The history of Kosmos-1707 shows another side of low-orbit operations: a spacecraft can cease functioning long before natural braking leads to its deorbit. The fact of atmospheric re-entry is confirmed by observation data. It is also indicative that in May 2018, its fall was already predicted – the spacecraft, contrary to expectations, remained in orbit for another eight years: deorbiting times strongly depend on the state of the atmosphere, which 'breathes' with solar activity.
Kosmos-1707 became the third Russian object to complete its flight in September: on September 7, the Progress MS-33 cargo ship was deorbited into the designated area of the Pacific Ocean, and on September 12, the Kosmos-2558 satellite, which had been in space since 2022, deorbited.
In total for September, according to the statistics of the 'Chronicle of the Space Era', 77 spacecraft completed their orbital existence – an average of about 2.57 per day. Russian objects accounted for about 3.9%, while Starlink satellites made up 59.7% of the monthly figure. In other words, approximately six out of ten spacecraft that completed their flight during the month belonged to the SpaceX constellation.