Atmospheric entry is the movement of human-made or natural objects as they enter the atmosphere of a celestial body from outer space—in the case of Earth from an altitude above the Kármán Line, (100 km). This article primarily addresses the process of controlled reentry of vehicles which are intended to reach the planetary surface intact, but the topic also includes uncontrolled (or minimally controlled) cases, such as the intentionally or circumstantially occurring, destructive deorbiting of satellites and the falling back to the planet of "space junk" due to orbital decay.
Most objects entering the atmosphere are not released from rest just above it, but rather are entering at hypersonic speeds because they are on suborbital (e.g. ICBM reentry vehicles), orbital (e.g. the Space Shuttle), or unbounded (e.g. meteors) trajectories. Therefore, controlled atmospheric entry often requires special methods to protect against severe aerodynamic heating. Various advanced technologies have been developed to enable atmospheric reentry and flight at extreme velocities.
Read more about Atmospheric Entry: History, Terminology, Definitions and Jargon, Blunt Body Entry Vehicles, Shock Layer Gas Physics, Thermal Protection Systems, Feathered Reentry, Inflatable Heat Shield Reentry, Entry Vehicle Design Considerations, Notable Atmospheric Entry Accidents, Uncontrolled and Unprotected Reentries, Successful Atmospheric Re-entries From Orbital Velocities, Selected Atmospheric Re-entries, Further Reading
Famous quotes containing the words atmospheric and/or entry:
“Nor has science sufficient humanity, so long as the naturalist overlooks the wonderful congruity which subsists between man and the world; of which he is lord, not because he is the most subtile inhabitant, but because he is its head and heart, and finds something of himself in every great and small thing, in every mountain stratum, in every new law of color, fact of astronomy, or atmospheric influence which observation or analysis lay open.”
—Ralph Waldo Emerson (1803–1882)
“All mothers need instruction, nurturing, and an understanding mentor after the birth of a baby, but in this age of fast foods, fast tracks, and fast lanes, it doesn’t always happen. While we live in a society that provides recognition for just about every life event—from baptisms to bar mitzvahs, from wedding vows to funeral rites—the entry into parenting seems to be a solo flight, with nothing and no one to mark formally the new mom’s entry into motherhood.”
—Sally Placksin (20th century)