Computers in Spaceflight: The NASA Experience

Is there a way to get the source code for such things ?

> Wow, how did they launch something to the orbit without any computer on-board? Was it just like a "dumb slingshot projectile"?

There was no on-board digital computer but there was quite sophisticated electronic circuitry for the era on board the Mercury spacecraft and the various launch vehicles that were used with it.

The guidance systems used mechanical gyroscopes wired to analog PID controllers built from vacuum tubes in early rockets and later from transistors and opamps.

There isn't a lot of control that you put into a space launch. After the initial subsonic pitchover maneuver, the spacecraft is just kept pointing nose to the direction of the travel. Any attempt to change the attitude of the space craft by turning it would cause the aerodynamic stress to tear the vehicle to shreds. Diverging from the nominal trajectory will start an abort or self destruct procedure. Errors accumulated from the launch will be corrected by the 2nd (or 3rd) stage (or the Mercury spacecraft in this case) using radar measurements from the surface.

While looking at this another book came up in Amazon's recommendation: The Apollo Guidance Computer Architecture. Luckily almost whole books is available for reading in Amazon't Look Inside feature: http://www.amazon.com/The-Apollo-Guidance-Computer-Architect...