The GRACE Follow-On spacecraft launched into orbit in May 2018. Credit: NASA/Bill Ingalls
The orbit insertion velocity near the Earth’s surface is practically the same as the Earth escape velocity of 11.2 kilometers per second, or 25,805 miles per hour.
Even at an altitude of 200 kilometers, a rocket is still inside the outer reaches of the Earth’s atmosphere. To really leave the atmosphere it probably has to get to a distance of 27,000 miles near the ‘geosynchronous’ limit. There is no sharp boundary to Earth’s atmosphere. It just decreases steadily in density until it eventually matches the density of the interplanetary medium. Here is an image that shows the extent of the geocorona, whose density is so low that it has no effect on spacecraft but qualifies as part of Earth’s atmosphere nonetheless. It was taken by NASA astronaut John Young using an ultraviolet camera on Apollo 16.
