Land deals meant to improve food security may have hurt

Large-scale land acquisitions by foreign investors, intended to improve global food security, had little to no benefit, increasing crop production in some areas while simultaneously threatening local food security in others, ...

Counting elephants from space, for the first time

For the first time, scientists have successfully used satellite cameras coupled with deep learning to count animals in complex geographical landscapes, taking conservationists an important step forward in monitoring populations ...

A-68A iceberg thinning at 2.5 cm per day

Latest images reveal that the A-68A iceberg has shattered into multiple pieces, with two large fragments of ice breaking off from the main berg and floating away in the open ocean. Scientists using satellite data have not ...

Satellite data identifies companies fishing in high seas

A team of researchers, using satellite data and other analytical tools, has identified companies fishing in high seas—waters that lie outside of national jurisdiction where fishing has raised fears about environmental and ...

Satellites can see the pollution trails from individual ships

All hands have to be on deck if the world is going to tackle degradation, and one of the biggest emitters is also one of the least well known—international shipping. A 2018 study estimated that pollution emitted from cargo ...

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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