Stability
An object in orbit at an altitude of less than roughly 200 km is considered unstable due to atmospheric drag. For a satellite to be in a stable orbit (i.e. sustainable for more than a few months), 350 km is a more standard altitude for low Earth orbit. For example, on 1958-02-01 the Explorer 1 satellite was launched into an orbit with a perigee of 358 kilometers (222 mi). It remained in orbit for more than 12 years before its atmospheric reentry over the Pacific Ocean on 1970-03-31.
However, the exact behaviour of objects in orbit depends on altitude, their ballistic coefficient, and details of space weather which can affect the height of the upper atmosphere.
Read more about this topic: Orbital Spaceflight
Famous quotes containing the word stability:
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—Andrew Jackson (1767–1845)
“Two things in America are astonishing: the changeableness of most human behavior and the strange stability of certain principles. Men are constantly on the move, but the spirit of humanity seems almost unmoved.”
—Alexis de Tocqueville (1805–1859)
“Every quotation contributes something to the stability or enlargement of the language.”
—Samuel Johnson (1709–1784)