Resumen de Elaboration of thermal control systems on heat pipes for microsatellites Magion 4, 5 and BIRD

Volodymyr Baturkin, Stanislav Zhuk, Jaroslav Vojta, Franz Lura, Bernd Biering, Horst-Georg Lötzke

• The strong restricted requirements to mass and power budget of microsatellite subsystems lead to choice of mainly passive thermocontrol system, specifically with heat pipe (HP) integration. An objective of this paper is to present the experience collected by authors in the field of elaboration and flight exploitation of thermocontrol systems (TCS) with heat pipes for microsatellites Magion 4 (1995), Magion 5 (1996) and BIRD (2001).

  Microsatellites Magion 4, 5 (Project INTERBALL) were completed with TCS including four low-temperature U-shaped heat pipes (fabricated by Kyiv Polytechnic Institute) installed in pairs on symmetrical facets of microsatellites’ bodies. Each pair of heat pipes was placed on two general flanges: one combined HP heating zones, the second combined their condensation zones. Heat pipes were fabricated from thin-wall copper shells with capillary structure of metal felt. Flanges were of aluminium, and acetone was used as heat carrier. Rated transferred heat power was not less than 60 W in the range of working temperatures from −20 to +50 °C.

  TCS for microsatellite BIRD included two U-shaped aluminium ammonia heat pipes (design and manufacture––Kiev Polytechnic Institute) symmetrically placed on opposite faces of the satellite. Heat pipe capillary structure was formed from 30 grooves of rectangular section. Rated transferred heat power reached 90 W in the range of working temperatures from −50 to +60 °C. Symmetrical layout of elements of TCS on microsatellite is the most acceptable due to stability of spatial orientation and geometrical symmetry of microsatellites and to enlarge the reliability of system operation.

  Microsatellites Magion 4, 5 and their parts have passed the full cycle of tests stipulated by Project INTERBALL. Currently Magion 5 active functioning exceeds 4.5 years and heat pipes’ operational time reaches 40 000 h. The microsatellite BIRD has passed the qualification and acceptance test programs and has been launched on 22.10.2001 by Indian Polar Satellite Launch Vehicle.

  Heat pipes’ technical characteristics, operating modes and their adaptation into TCS design, test and flight operation results are presented.