According to data collected by the University of Calgary, space begins and the Earth's atmosphere ends at 73 miles above the Earth's surface. However, other countries and agencies have a differing opinion on where space begins.
Although the United States does not have a defined boundary, NASA considers the Earth's atmosphere ending and beginning at 76 miles above the surface. This is the point where the Space Shuttle would begin using air to maneuver instead of thrusters. Some scientists argue that space does not begin until 13 million miles out; this is point where Earth's gravity does not have any influence on an object.