3-D Earth in the making

A thorough understanding of the 'solid Earth' system is essential for deciphering the links between processes occurring deep inside Earth and those occurring nearer the surface that lead to seismic activity such as earthquakes ...

Video: Water cycle wrapped

As our climate changes, the availability of freshwater is a growing issue for many people around the world. Understanding the water cycle and how the climate and human usage is causing shifts in natural cycling processes ...

NASA Northern quadrant strength in Tropical Cyclone Lili

NASA's Aqua satellite used infrared light to analyze the strength of storms in Tropical Cyclone Lili as it moved through the Southern Indian Ocean. Infrared data provides temperature information, and the strongest thunderstorms ...

NASA reveals heavy rainfall in Tropical Cyclone Fani

Satellite data revealed heavy rainfall in powerful Tropical Cyclone Fani before it made landfall in northeastern India. Fani brought that soaking rain to the region and continues to drop heavy rainfall on May 3, as it moves ...

NASA goes infrared on powerful Tropical Cyclone Fani

NASA's Aqua satellite focused an infrared eye on a very powerful Tropical Cyclone Fani as it approached landfall in northeastern India. Fani is a powerful Category 4 hurricane on the Saffir-Simpson Hurricane Wind Scale.

Scientists track giant ocean vortex from space

Researchers have found a new way to use satellites to monitor the Great Whirl, a massive whirlpool the size of Colorado that forms each year off the coast of East Africa, they report in a new study.

New mathematical approach tested for the search of flight MH370

The 2014 disappearance of Malaysia Airlines Flight MH370 remains ones of the biggest mysteries in aviation. More than $150 million has been spent so far to identify where the plane carrying 239 passengers crashed into the ...

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Satellite Data System

The Satellite Data System (SDS) is a system of United States military communications satellites. At least three generations have been used: SDS-1 from 1976 to 1987; SDS-2 from 1989 to 1996; SDS-3 from 1998 to the present. SDS satellites have a highly elliptical orbit, going from about 300 kilometers at perigee to roughly 39,000 km at apogee in order to allow communications with polar stations that cannot contact geosynchronous satellites. The high apogee meant that the polar regions were visible for long amounts of time, and only two satellites were required in order to achieve constant communications ability. The SDS satellites were constructed by Hughes Aircraft.

The primary purpose of the SDS satellites is to relay imagery from low-flying reconnaissance satellites to ground stations in the United States.

Each SDS-1 satellite had 12 channels available for ultra-high frequency communication. They were cylindrical in shape, roughly 25 feet (7.6 m) long. 980 watts of electrical power were available from solar panels and batteries. The SDS-1 had a mass of 1385 pounds (630 kilograms) and was launched on Titan-3B rockets. The SDS-1 satellites had similar orbits to the Air Force's Jumpseat ELINT satellites.

The SDS-2 is significantly more massive at 5150 pounds (2335 kg), with three separate communication dishes, including one for a K band downlink. Two dishes are 15 feet (4.5 meters) in diameter, while the third is 6.6 feet (2 m) in diameter. The solar arrays generate 1238 watts of power. It is believed that the Space Shuttle has been used to launch several satellites, possibly on missions STS-28, STS-38, and STS-53. Other launches have used the Titan-4 rocket.

Quasar is the rumored code name for the communications satellite.

A recent Quasar may have been launched into a high-apogee orbit from Cape Canaveral on August 31, 2004 by an Atlas 2AS rocket.

This text uses material from Wikipedia, licensed under CC BY-SA