Mike dOctober 24, 2012Xenotron: Great wikipedia source. Takes me back to my missile days...
Andy's Cat: Looking at the film, I'd say the re-entry angle was around 3 to 5 degrees.
Considering Prometheus traversed space to LV223 in over two years, a space warp technology would be used to do the job. Magnetic field production strong enough to warp space would presumably also be able to produce force fields around the ship to act as a way to slow the ship down from orbital speed using the force fields as the shield itself.
At a re-entry angle of 3 to 5 degrees, the force field would act as an 'aerobrake' to slow Prometheus from orbital speed (say, 17,800 mph if LV223 is similar to earth in mass and gravity); Prometheus 'bleeds off" the speed as it de-orbits and the heat from atmospheric friction is dissipated by the force field.
The 3 to 5 degree of attack also allows Prometheus to complete its scan of LV223's surface covering a large area of the planet a one time. It may take two full trips around LV223 to complete planetary coverage and identify the areas of metal mentioned in the film.
Descent after re-entry into the atmosphere would probably be around 3 degrees, which is around the glide slope used by aircraft for landing. It is an angle of approach that gives the pilot ample time to access the landing spot without bringing the aircraft in too steeply or too fast.
Just a thought...