Interkosmos 25 [Yuzhnoye]
Official name INTERCOSMOS 25
Alternative name Interkosmos-25 (APEX)
Cospar ID 1991-086A
Norad ID 21819
Launch date 1991-12-18
Launch site PKMTR
Launch vehicle Tsiklon-3
Country/Organization International
Type application Science
Operator Interkosmos
RCS size LARGE
Decay date ON ORBIT
Period (min) 119.14
Inclination (deg) 82.61
Perigee (km) 438
Apogee (km) 2847
Eccentricity 0.733333333333333
Mean motion (revs. per day) 12.086620782273
Semi-Major axis (km) 8020.635
Raan (deg) 355.7495
Arg of perigee (deg) 123.7096
Shape Cyl + 2 Pan + 2 Ant
Mass (kg) 991.1
Diameter (m) 1.5
Height (m) 2.5
Span (m^2) 23
Lifetime 6 months
Contractors Yuzhnoye
Configuration AUOS-Z
Power 8 deployable fixed solar arrays, solar cells, batteries

The only dedicated Soviet science mission of the year 1991 lifted off from Plesetsk aboard a Tsiklon-3 booster. Intercosmos 25 was part of the APEX (Active Plasma Experiment) program to investigate the effects of streams of electrons and beams of plasma on the ionosphere and magnetosphere. The spacecraft was cylindrical, measuring 1.8 m long, 1.5 m in diameter. Eight solar panels extended in petal-like fashion from one end. It weighed about one metric ton at launch. A Czechoslovakian subsatellite, Magion 3, was deployed from Intercosmos 25 on December 28.

Satellite COSPAR Date LS Launch Vehicle Remarks
INTERCOSMOS 25 1991-086A 1991-12-18 PKMTR Tsiklon-3 with Magion 3