Artificial satellites in retrograde orbit

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Artificial satellites are rarely placed in retrograde orbit. This is partly due to the extra velocity required to go against the direction of the rotation of the earth.

1 Examples
2 Space warfare and accidents
3 See also
4 Sources and external links

[edit] Examples

Israel has successfully launched five Shavit satellites in retrograde orbit. One or more of these are spy satellites. They were launched in retrograde orbit so that launch debris would land in the Mediterranean Sea, and not on Israel's Arab neighbors.

Earth-observing satellites may also be launched into a sun-synchronous orbit, which is slightly retrograde. This is typically done in order to keep a constant surface illumination angle, which is useful for observations in the visible or infrared spectrums. SEASAT and ERS-1 are examples of satellites launched into sun-synchronous orbits for this reason.

[edit] Space warfare and accidents

Arthur C. Clarke wrote an article called, "War and Peace in the Space Age," in which he suggested that an artificial satellite in retrograde orbit could use "a bucket of nails" to destroy an SDI (anti-warhead) satellite. This premise was ridiculed on account of the vastness of space and the low probability of an encounter.

Nevertheless, a satellite in retrograde orbit could pose a major hazard to other satellites, especially if it where placed in the Clarke belt, where geostationary satellites orbit. This risk highlights the fragility of communication satellites and the importance of international cooperation in preventing space collisions due to negligence or malice.