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:
“Free from public debt, at peace with all the world, and with no complicated interests to consult in our intercourse with foreign powers, the present may be hailed as the epoch in our history the most favorable for the settlement of those principles in our domestic policy which shall be best calculated to give stability to our Republic and secure the blessings of freedom to our citizens.”
—Andrew Jackson (1767–1845)
“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)
“Chastity is the cement of civilization and progress. Without it there is no stability in society, and without it one cannot attain the Science of Life.”
—Mary Baker Eddy (1821–1910)