Stephen Coester added 2 new photos.

March 22 at 9:33am · 

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Another for Space Shuttle interested folks.

Today I'll try to very simply discuss a very complex subject. There are several excellent in depth discussions of the Space Shuttle Launch Processing System (LPS) you can google for the details.

Twenty years before the advent of desktop computers NASA decided that it needed to get away from the hardwired switches and gauges used to launch Apollo. The system needed to be totally computerized to control all aspects of checkout and launch. LPS was the result with the CCMS or Checkout Control and Monitoring subsystem at its heart. The CCMS is all of those consoles you see in the firing rooms.

KSC was given the task of developing this radical new way of processing and did so in a lab next to the O&C building that previously had been used for Apollo moon landing simulations.

What did this new system mean to the system engineers on the Shuttle? On my jobs on both Apollo-Saturn V and Atlas-Centaur the firing room or blockhouse had individual consoles for each function like propulsion, propellants, pneumatics, etc. Using the knobs, switches and gauges on his specific console the engineer would operated his system.

Not so on the CCMS. In the firing room were twelve consoles each having three computer stations. And all of these stations were identical until loaded with a particular system's software. I had this explained to me my first week and asked where did this software come from so I could control my Main Propulsion System. To my shock I who had never seen a computer was told we system engineers would write that software.

Each of us system engineers then attended GOAL school. GOAL or Ground Oriented Aerospace Language was a new English language based software system that let us write our software with minimum knowledge of ones and zeros.

First we developed displays for the computer screens that schematically showed the system and all of it's valves, instrumentation and other hardware. Then we spent months pouring over the electrical drawings and converting all of that complex logic into code.

Once written, compiled and verified this software would be loaded on one of those CCMS computer stations and we were finally ready to start cycling valves, running automated tests, and launching the Space Shuttle.

Here's an example of what LPS could do. I didn't write this software except some of the MPS part, but helped with the loading criteria. Jimmy Rudolph and Mark Dezendorf get credit for the propellant loading software. 

A typical example of the LPS at work can be shown by following the liquid oxygen tank sequence when a Shuttle is on the pad. Only one console is required for this operation. Its task is to transfer some 529,000 liters (140,000 gallons) of a super-cold liquid at minus 181 degrees C (-295 degrees F) one-third of a mile, from the liquid oxygen tank at the edge of the pad to the external tank.
 The console operator performs several programs to verify that the system is ready to begin the fill operation. These programs establish that; 1) All exception monitor limits are set to their standby conditions; 2) All system measurements are being reported; and 3) All mechanical valves are cycled to determine their readiness to operate. The LPS does all this without operator intervention, finishing, unless unusual conditions occur, in about ten minutes.

When the verifications are complete, the operator awaits a "go" signal from the lead test conductor. When this signal comes, the operator pushes a single button marked "Fill." The liquid oxygen loading operation begins, and continues automatically until completion. It includes these major steps:

 A) A ten-minute chilldown of the storage area and pump. (Liquid oxygen flashes into a gas if it contacts surfaces warmer than minus 181 degrees C. All pipes, pumps, tanks etc., have to be prechilled to prevent an excess amount of gaseous oxygen from forming.)
 B) A chilldown of the Shuttle orbiter main engines, through which the liquid passes on its way to the external tank and the oxygen tank itself.
 C) A slow fill of the oxygen tank, until it is two percent full.
 D) A much faster fill of the oxygen tank, until it is 93 percent full.
 E) A slower "topping" of the tank to 100 percent.
 F) The constant replenishment of the oxygen boiled off and bled off in gaseous form, until about nine minutes before launch.
 G) At ignition minus nine minutes, the liquid oxygen tank is sealed, pressurized and ready for launch.
 Some 200 computer programs are required to operate all these phases of action. They operate a primary pump or secondary pump, primary fill valve, etc., throughout a complex piping system. While these programs are in process, some 150 measurements are constantly monitored to be certain all temperatures, pressures, etc., are within limits. If a condition is detected which requires immediate corrective action, the program takes that action and notifies the operator. Less immediate problems are called to the operator's attention for his consideration. The operator has the option to alter the sequence of events or take over control, in the unlikely event that he or she should think it necessary.
 The loading of liquid oxygen is only one of hundreds of equally complicated, difficult operations performed automatically by the LPS, while operating under stringent safety and performance requirements. The end result is the launch of a Space Shuttle