Supplemental to Organic Marble's answer from the requirements, some discussion on the thought process behind them is in the book 'Into the Black' which while not necessarily the most up to date source does include information from members of the military who ended up absorbed into the shuttle program.

The early spy satellites used film cameras and then deployed the film in capsules for recovery by aircraft that hooked the parachutes out of the sky. This functioned for routine work but cases where either the film was recovered too late to be useful or a capsule had to be 'wasted' by releasing early occurred along with capsules not being recovered at all. This was also expensive as once the in orbit satellite ran out of film a new one needed to be launched, even if the original was otherwise fully serviceable.

One solution for this was the process the time critical images in orbit, and was the thought behind the USAF MOL program which while not flying hardware did a lot of design and concept work and had a cadre of astronauts in training before the program was cancelled, with the cancellation being based in part that the shuttle program could fulfill the same role in supporting surveillance satellites by either servicing them or recovering them entire.

In the case intelligence was urgent this recovery would need to minimize the time between taking the image and the film being analyzed on Earth, and assuming recovery into the same country this produces the 'launch, recover whole satellite, re-entry' requirement. The mostly over ocean ground track and single pass also made it a harder ASAT target given the urgent intelligence need might be because a war had started.

In practice CCDs become more capable and even at lower image quality than film allowed near mealtime images to be produced without needing a manned vehicle at all.

Supplemental to Organic Marble's answer from the requirements, some discussion on the thought process behind them is in the book 'Into the Black' which while not necessarily the most up to date source does include information from members of the military who ended up absorbed into the shuttle program.

The early spy satellites used film cameras and then deployed the film in capsules for recovery by aircraft that hooked the parachutes out of the sky. This functioned for routine work but cases where either the film was recovered too late to be useful or a capsule had to be 'wasted' by releasing early occurred along with capsules not being recovered at all. This was also expensive as once the in orbit satellite ran out of film a new one needed to be launched, even if the original was otherwise fully serviceable.

One solution for this was the process the time critical images in orbit, and was the thought behind the USAF MOL program which while not flying hardware did a lot of design and concept work and had a cadre of astronauts in training before the program was cancelled, with the cancellation being based in part that the shuttle program could fulfill the same role in supporting surveillance satellites by either servicing them or recovering them entire.

In the case intelligence was urgent this recovery would need to minimize the time between taking the image and the film being analyzed on Earth, and assuming recovery into the same country this produces the 'launch, recover whole satellite, re-entry' requirement. The mostly over ocean ground track and single pass also made it a harder ASAT target given the urgent intelligence need might be because a war had started.

In practice CCDs become more capable and even at lower image quality than film allowed near realtime images to be produced without needing a manned vehicle at all.