After 32 years of serving ships at sea and scientists at the South Pole, an aging communications satellite owned by Intelsat Ltd. has been retired.

The Marisat-F2 satellite, manufactured by Hughes Aircraft Inc. and launched in 1976, had only a five-year design life, yet until the end, the communications payload continued operating within its original specifications, Intelsat engineers said. Once dubbed "The Little Satellite That Could," Marisat-F2 is believed to have been the oldest commercial communications satellite still actively operating in space.

Engineers at Intelsat General responsible for managing the orbit of the 700-pound satellite determined recently that its support sub-systems were finally near the end of operating life. To prevent Marisat-F2 from drifting into the path of other satellites, Intelsat decommissioned it on Oct. 29th and began using its remaining fuel to raise it about 125 miles to disposal altitude, out of the way of other geosynchronous communications satellites.

The final assignment of Marisat-F2 had been to provide Internet service to research scientists stationed at the Amundsen-Scott South Pole Station. Of the three satellites dedicated to serving the National Science Foundation's research operations there, Marisat-F2 had the second greatest bandwidth capacity for Internet service and was available for use the most hours each day, officials said.

"The performance of this satellite has been truly remarkable," said Kay Sears, President of Intelsat General, the government services subsidiary of Intelsat. "No one could have ever imagined that its power supply and batteries could have lasted this long. The longevity of this satellite is a testimony to manufacturing quality at Hughes and optimum care by its ground-based controllers."

Marisat-F2 was one of three Marisat satellites launched by Comsat General Corp. (a company later acquired by Intelsat) in the 1970s to service the maritime communications needs of the U.S. Navy and commercial shipping around the world. The other two Marisat satellites were retired in the 1990s, but Marisat-F2 continued to operate satisfactorily and in 2000 was moved from an orbit above the Indian Ocean to one above the Atlantic.

Marisat-F2 had always been in "inclined" orbit, meaning it appeared to move a few degrees above and few below the equator on each trip around the Earth. Engineers said the original inclination was 3 degrees and grew to13 degrees over the satellite's lifetime.

The inclination growth made it ideal for use by Amundsen-Scott South Pole Station. The station, at the very bottom of the world, cannot see most communications satellites orbiting above the equator. Once the Marisat inclination exceeded 9 degrees from the equatorial plane, it appeared over the horizon at the South Pole and eventually provided 6 hours of coverage per day. The satellite was moved over the Atlantic Ocean to provide a direct link back to the US via a new 9-meter antenna that was built at the South Pole to provide service, an engineering feat in itself.

According to Patrick Smith, Manager of Technology Development, Antarctic Infrastructure & Logistics for the NSF, "for the past eight years, Marisat-F2 played a critical role transmitting scientific data from the South Pole station to scientists analyzing it in the United States and around the world. Marisat-F2 has a capacity of 1.5 megahertz in each direction for Internet access, far more than one of the other two satellites used by the station -- GOES-3, launched in 1978, and TDRS-1, launched in 1983."

Marisat-F2 had been used mainly for Internet services such as phone calls, video conferencing, remote science research instrumentation management, software updates and emergency telemedicine. Marisat-F2 appeared above the horizon two hours earlier than the other two satellites, and when combined with the others the community at the research station obtained Internet access for up to 11½ hours each day. The population at the research station ranges from around 50 in the winter to 150 scientists and support staff in summer months.

"Marisat carried a lot of traffic and was very important to what we do," Smith said. "It was by far our best performer for Internet service, which was pretty amazing for a satellite with a five-year design life."