Coming from a question about distances between satellites in GEO, what liquid propulsion systems do a majority of GEO satellites carry to maintain their slot positions? It is easy to find information about Merlin engines, SSME, Rocketdyne F-1, etc., but smaller purpose engines are harder to find.


Thanks for the info about the propellents used. What about the engines?


3 Answers 3


Typically GEO satellites use either mono-prop (often hydrazine) or bi-prop (often Mono Methyl Hydrazine and Nitrogen Tetroxide) storable propellant engines for station keeping. Electric propulsion is a technology that is also used for GEO spacecraft station keeping (http://spaceflightnow.com/news/n1203/19boeing702sp/).


Some examples of small engines:
Northrop Grumman Bipropellant thrusters:

-TR-308 Liquid Apogee Engine, which placed the NASA Chandra X-ray Observatory spacecraft into its final orbit. The Liquid Apogee Engine (LAE) is the world's highest performing apogee engine.
-TR-312 Liquid Apogee Engines (TR-312-100MN and TR-312-100YN) which have completed DVT testing for commerical geostationary comsat applications.
-TR-500 Secondary Combustion Augmented Thruster (SCAT) Bi-Modal Thruster, flight-proven on the National Reconnaissance Office's Geosynchronous Lightweight Technology Experiment (GeoLITE) program.
-TR-711 Gel Boost Engine, which powered the world's first flight of a tactical missile utilizing gelled propellants and achieved a 700:1 Thurst-to-Weight Ratio.
-LOX/LH2 and LOX/Ethanol RCS engines successfully test fired in 1000 lbf and 870 lbf configurations, respectively.
-NASA RCE contract for a 100 lbf class LOX/Methane. 

Monopropellant thrusters - several models between 1 and 86 N, using hydrazine.

Aerojet Rocketdyne:
Monopropellant thrusters, hydrazine, 1-3100 N.
Biprop thrusters, MMH/NTO or Hydrazine (N$_2$H$_4$)/NTO, 22 N-4 kN.

EADS Astrium:
bipropellant thrusters 4-200 N, MMH and N$_2$O$_4$ or mixed oxides of nitrogen (MON)
hydrazine thrusters 1-400 N
Apogee engines, MMH and N$_2$O$_4$ or mixed oxides of nitrogen (MON)
ion engines, thrust 50 $\mu$N to 200 mN


Try this link for a few small thruster types. Its out of date, the names of manufacturers have changed since this list but the thruster names are probably still in use. https://engineering.purdue.edu/~propulsi/propulsion/rockets/satellites.html

  • 1
    $\begingroup$ This is essentially a link only answer, so it might become obsolete if the link changes or becomes unavailable. Please edit to include essential information required to answer the question here. Thanks! $\endgroup$
    – TildalWave
    Commented Oct 13, 2015 at 21:52
  • $\begingroup$ TRW is now part of Northrop Grumman, most of the others ended up in Aerojet Rocketdyne. $\endgroup$
    – Hobbes
    Commented Oct 14, 2015 at 10:10
  • $\begingroup$ OK, I understand, thanks for the reminder. I think Hobbes' answer covers it quite well. $\endgroup$
    – Puffin
    Commented Oct 15, 2015 at 0:44

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