How low can you orbit?

From Chris Jones:
The shuttle's so-called direct insertion trajectory puts it into an
"orbit" with a perigee around 30 miles and an apogee above 200 miles.
This is not an orbit that will last even twice around the earth, which
is the reason for the OMS burn performed at first apogee to raise the
perigee safely out of the dense atmosphere. Even the reentry burn
doesn't really take a spacecraft out of orbit; it lowers the perigee so
low (around 20 - 30 miles) that the frictional losses quickly do the
rest and take the spacecraft out of orbit.

requote:

"Even the reentry burn doesn't really take a spacecraft out of orbit"

Now that I think about it, the actual _deorbit_burn doesn't take place
until the tiles start getting red hot. Ha!


~ CT