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Villafranca Satellite Tracking Station
MARECS Missions Description
The MARECS missions were designed with the objective to provide high quality full duplex, real-time voice, data and teleprinter services between ship earth stations and coast earth stations for a minimum life time of 5 years:
The two spacecrafts consist of a service module and a payload module and are three-axis stabilised. They are identical with the exception that MARECS-A is supplied with 10 solar array sections and MARECS-B2 with 12 sections.
The spacecrafts are approximately 2 m wide and 2.5 m high, with a 2 m L-Band dish antenna.The solar arrays extend between 14 m from tip to tip. Spacecraft mass at launch was 1015 Kg. The two satellites are positioned in a geosynchronous orbit.
The Shore to Ship link (Forward Link) through the satellites is established at C-Band for the up-path (6420.25-6425 MHz) and at L-Band for the down-path (1537.75 - 1542.5 MHz). The Ship to Shore Link (Return Link) is performed at L-Band for the up-path (1638.6 - 1644.5 MHz) and at C-Band for the down-path (4194.6 - 4200.5 MHz).
The Flight Control Centre is located at ESOC and the TT&C ground station working at C-Band at Villafranca. A back-up VHF TT&C station and telemetry reception in C-Band is located at Redu.
MARECS Missions History
MARECS-A was launched on December 19, 1981 and MARECS-B2 on November 9, 1984. Both satellites were leased to INMARSAT to provide maritime satellite communication services in the Atlantic Ocean Region (MARECS-A) and in the Pacific Ocean Region (MARECS-B2).
In 1986 INMARSAT requested to relocate the two MARECS satellites. Thus MARECS-B2 was moved from the Pacific Ocean Region (POR) to the Atlantic Ocean Region (AOR), whilst MARECS-A was moved to the POR to be used as in standby.
In 1991 MARECS-A was removed from INMARSAT services and relocated to 22.5╟ East due to an extended degradation of solar array sections and has since then been successfully used by ESA for land mobile experimental communications with the ground based PRODAT terminal being located at Villafranca and later at Lario (Italy).
Following a request of INMARSAT, MARECS-B2 was moved in 1990 to 55.5╟ West to cover a new region (AOR-West) with prime maritime communication services.
The new relocation was preceded by an extensive campaign of 28 manoeuvres compressing effectively three years of North-South station keeping into three months. 38 Kg hydrazine were expended in 33 hours of thruster firings, to impart a delta V of 132 m/sec.
Finally in 1992 INMARSAT requested to relocate MARECS-B2 to 15╟ West (AOR-East), where the satellite is being used since December 1992 in a dual satellite operations system.
The future prospects of the two satellite missions are primarily limited by the increasing degradation of the solar array sections.
Inmarsat 3's C-band (6.4/3.6 GHz)
Inmarsat 3's L-band (1.6/1.5 GHz)
Milstar 1 series
Low Data Rate payload (75 bps to 2400 bps):
Nato 4's UHF-band (250-315 MHz)
Nato 4's X-band
Skynet 4's (D, E, F) UHF-band (254-318 MHz)