CAPE CANAVERAL, Fla. -- A NASA communications satellite launched into orbit March 8 has developed a problem with its onboard supply of propellant, officials said in a statement released Friday.
At best the trouble is delaying the Tracking and Data Relay Satellite-I (TDRS-I) from reaching its ultimate destination, a circular orbit about 22,300 miles (35,800 kilometers) above Earth's equator. The satellite's current egg-shaped orbit is 22,236 miles (35,800 kilometers) at its highest and about 4,970 miles (8,000 kilometers) at its lowest.
But if the spacecraft's manufacturer, Boeing Satellite Systems (BSS), cannot find a solution to the problem, the satellite -- one-third of an $840 million NASA program to upgrade its communications network -- could be declared a total loss.
Boeing officials are hopeful that their engineers will ultimately be able to deliver the satellite into its proper orbit, after which they will turn operations of TDRS-I over to NASA and the spacecraft will be renamed TDRS-8.
"BSS has been conducting a thorough investigation into the cause of the anomaly and has developed and is implementing procedures to get the satellite to its operational geosynchronous orbital position," the company said in a statement. "BSS intendsto meet the established mission requirements and hand over the satellite in accordance with the customer's operational need date."
The TDRS-I was launched from Cape Canaveral atop a Lockheed Martin-built Atlas 2A rocket and successfully placed into what's called a geostationary transfer orbit -- the egg-shaped orbit the satellite is in now.After separating from the rocket's Centaur upper stage, it's up to the satellite's own onboard propulsion system to make a series of engine firings that raises the low end of the orbit to match the high end, making the orbit essentially a circle.
Four propellant tanks feed the onboard thrusters but Boeing engineers are seeing there is a problem with the supply in one of those tanks.
The TDRS system is considered critical to every major NASA spaceborne program from the International Space Station to the Hubble Space Telescope.
Television, science data, radio signals, spacecraft telemetry and even e-mail is relayed between Earth and space thanks to this network of spacecraft, the first of which was launched into orbit by the space shuttle Challenger in 1983.
But with a growing demand for more communication services from an aging TDRS fleet that were designed to last seven years, but are on average now more than 12 years old, NASA in 1995 began an effort to orbit three modernized and more capable TDRS.
The first of the three, TDRS-H, was launched by an Atlas 2A rocket in June 2000. TDRS-I was the second and a third, TDRS-J, is to be lofted by an Atlas later this year, perhaps in November. Although that flight could be delayed if Boeing needs to implement any major changes to the spacecraft still at its factory.
The trio of enhanced spacecraft include improvements that will allow, for example, high-resolution TV signals to be beamed between a space shuttle and the ground, as well as relaying enormous amounts of data at speeds 5,000 times faster than a typical 56K home computer modem.
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