New ground station at South Pole to help maintain communications
Posted April 10, 2009
A new satellite communications system at South Pole Station will help keep science data flowing after an older satellite operating well past its prime succumbs to old age.
South Pole Station currently has about 9.5 hours of satellite coverage, during which only about six hours are available for high-speed data transmission, mainly for large astrophysical experiments. About 120 gigabytes of data move during this timeframe, at transmission rates of up to 150 megabits per second — more than 10,000 times faster than the 14.4 kilobits per second of modems from not too long ago.
Since 1998, the U.S. Antarctic Program (USAP) has used NASA’s Tracking Data and Relay Satellite Flight 1 (TDRS F1), now nearing the end of its life, as one of its communications satellites for South Pole. It could fail tomorrow or last a few more years. No one knows for sure, but one thing is certain: the satellite is operating well beyond its design life of eight years.
Just last October, engineers decommissioned another aging satellite, Marisat-F2 , dropping the South Pole satellite window by two hours. [See related story: Outliving expectations.] Large experiments such as the IceCube neutrino detector and South Pole Telescope need all the bandwidth they can get, so a diverse team of engineers and technicians went to work to design and install a new system to save the communications pipeline from deteriorating further.
The original South Pole TDRS Relay satellite ground station (SPTR-1, pronounced “spitter one”) uses a fixed-point antenna and an electronics suite incompatible with the rest of NASA’s TDRS satellites and ground station network. When TDRS F1 fails, the SPTR-1 system will become obsolete.
Enter SPTR-2, a full-motion, 4-meter satellite dish housed on a new elevated platform under a radome for shelter. The full-motion capability of SPTR-2 allows it to track satellites as they rise briefly above the South Pole horizon. The ability to point the antenna not only extends the availability of the TDRS F1 satellite over that of the SPTR-1 fixed antenna, but it also gives SPTR-2 the ability to turn to other satellites as they rise at different positions on the horizon.
The National Science Foundation (NSF) , which manages the USAP, has exclusive use of the 26-year-old TDRS F1 satellite, so the new SPTR-2 ground station will continue to pass data across it until the satellite is decommissioned. When TDRS F1 fails, communications will move to other NASA satellites — TDRS F4, F5 and F6.
But there’s a catch. These other satellites have many other users, meaning South Pole will have to share communication time and space with the Hubble Space Telescope, Space Shuttle and many others, although South Pole will be the only one using the network from an Earth-based location.
Changes in TDRS satellite service will mean changes in the way science data and personnel interact with their colleagues in the United States and around the world. This represents another evolution in South Pole station operations, one of the most unique and challenging places to live and work on the planet.