Ekspress-AM 4

Spacecraft n°:

Russian spacecraft n°:

Launch data: Designation  37798 / 11045A Launch date  17 Aug 2011 - 21:25 UT Launch site  Baik, LC-200/39 Launch vehicle  Proton-M/Briz-M Mission  Communication Earth orbit: Perigee / Apogee  655.7 x 20422.0 km Eccentricity   Inclination  51.1 deg Period  364.7 min

Description:

• Express-AM4 is a new powerful communications satellite built by Europe’s satellite manufacturer Astrium in association with Russia’s Khrunichev Space Center for Russian Space Communications Company, RSCC.
• The Express-AM4 spacecraft is based on the highly successful Astrium’s Eurostar E3000 satellite design. Since the launch of the first ever Eurostar in 1990, over 45 Eurostars have been successfully delivered to geostationary orbit, clocking up a total of nearly 400 years of service.
• Express-AM4 has 63 active transponders operating in L, C, Ku and Ka bands. Its twelve antennas will provide high performance coverage over the Russian Federation and the CIS countries and its steerable antennas can be used to provide communication to any point within the satellite’s field of view. With an electrical power of more than 16 kW, Express-AM4 is the most powerful satellite ever built in Europe.
• Designed for 15 years of service, Express-AM4 will be positioned in geostationary orbit at 80° East longitude, Russia’s key orbital communications location. RSCC is currently looking for high power satellites to complement its existing fleet and fulfill growing needs for satellite capacity. Express-AM4 is the first and major milestone in this ambitious program.

Mission details:

• The Russian Ekspress AM-4 communications satellite was delivered to an incorrect orbit on Aug 18 when a Proton-M's Briz-M upper stage malfunctioned.
• The first two Briz-M burns, to 173 x 173 km, and 270 x 4998 km were successful. The third burn, at 0052 UTC on Aug 18, seems to have gone wrong and the DTB tank separated to a low 145 x 11340 km x 49 deg orbit; after the fourth burn the payload ended up in a 694 x 20242 km orbit instead of one with geosynchronous apogee. The Briz-M stage orbit was 1016 x 20900 km following a depletion burn at around 0946 UTC on Aug 18.
• Russian authorities have announced that a timing error in the inertial platform led to incorrect orientiation of the stage during the later burns.
• In August 2011 a Proton-M/Briz-M delivered the Ekspress AM-4 spacecraft to an incorrect orbit of 697 x 20239 km x 51.3 deg.
  On around Mar 1, 2012 the satellite's apogee began to decrease slightly, presumably due to tests of the propulsion system. Between Feb 27 and Mar 24 the orbit was slowly and steadily lowered from 651 x 20410 km to 659 x 20320 km x 51.1 deg. On Mar 25, 2012 the Ekspress AM-4 spacecraft was deorbited on command from the Centre Spatiale de Toulouse. An engine burn from 0945 to 1035 UTC over the southern Indian Ocean, as Ekspress AM-4 was approaching apogee, lowered the satellite's perigee with a resulting orbit of around (-2000 to -1000) x 20320 km, and it reentered over the N Pacific near 40N 175W at around 1332 UTC. The Briz-M stage from the launch remains in a 1008 x 20307 km x 51.1 deg orbit.