The feature of the “Express-AMU3”, “Express-AMU7” spacecrafts injecton to geostationary orbit

Today satellite orbit raising to geostationary orbit by own propulsion to increasing of SC mass has become wide application. Thus ISS has employed orbit raising for a number of satellites built in-house such as Express-AM5, Express-AM6, Express-80 and Express-103. At the same time it should be noted that there is a variety of orbit raising methods. In particular the above satellites were orbit raised using onboard SPT-100 thruster based propulsion subsystem. The whole operation was carried out using a single thruster or a thruster pair. Orbit raising of Express-80 and Express-103 done by a thruster pair was due to the need to meet the constraint of six month orbit raising duration while the launch mass was significantly exceeding the launch vehicle capability. However the orbit raising maneuver duration of approximately 150 days which took place upon the said satellite orbit raising is still too large. It is desirable to reduce it as much as possible. It is evident that under equal circumstances this duration could be reduced by increasing the number of thrusters fired simultaneously. Therefore for the upcoming Express-AMU3 and Express-AMU7 satellite (featuring the same size class as Express-80 and Express-103) where paired launch is expected both methods have been implemented. Two SPT-100B thrusters and an additional SPT-140D thruster have been embarked upon these satellites. The overall thrust of the thruster combination enables a major decrease in the orbit raising duration versus Express-80 and Express-103 program. It is the first time that SPT-140 thruster built by EDB Fakel has been embarked upon a Russian satellite. A dedicated SPU-140D power processing unit was designed and built by Polyus Research and Production Center to supply SPT- 140 with power. The three thrusters combination enables significantly reducing the duration of orbit raising to geostationary orbit.