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:
“Traditions are the “always” in life—the rituals and customs that build common memories for children, offer comfort and stability in good times and bad, and create a sense of family identity.”
—Marian Edelman Borden (20th century)
“The world can be at peace only if the world is stable, and there can be no stability where the will is in rebellion, where there is not tranquility of spirit and a sense of justice, of freedom, and of right.”
—Woodrow Wilson (1856–1924)
“Every quotation contributes something to the stability or enlargement of the language.”
—Samuel Johnson (1709–1784)